Psychiatry Research 215 (2014) 634–640
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Smoking and suicidality in patients with a psychotic disorder Anoop Sankaranarayanan a,n,1, Serafino Mancuso b,2, David Castle c,d,3 a
Hunter Valley Mental Health Service, 10/555 High Street, Maitland, NSW 2320, Australia St Vincent0 s Mental Health, PO Box 2900, Fitzroy, VIC 3065, Australia St. Vincent0 s Hospital Melbourne, Australia d Department of Psychiatry, University of Melbourne, Australia b c
art ic l e i nf o
a b s t r a c t
Article history: Received 11 April 2013 Received in revised form 4 December 2013 Accepted 16 December 2013 Available online 24 December 2013
Cigarette smoking has been associated with an increased risk of suicide. Patients with psychosis are more likely to smoke cigarettes and are also at an increased risk of suicide. The aim of this study was to compare risk for suicidal behavior among patients with psychosis who were current smokers, previous smokers and nonsmokers. We studied 1812 of the 1825 participants who took part in the Australian Survey of High Impact Psychosis (SHIP) for whom smoking data was available. We identified predictors for lifetime suicide attempts using univariate logistic regression analysis. These variables were retained for the multiple logistic regression models if they were a significant predictor of lifetime suicide attempts. A series of multiple logistic regressions were then conducted to predict lifetime suicide attempts using current smoking status and lifetime smoking status as independent variables, respectively, while controlling for the retained predictor variables. Current smoking and lifetime smoking were statistically significant predictors of lifetime suicide attempts. However adding the covariates to a logistic regression model reduced this association to non-significance. The strongest predictors were self-harm in the past 12 months, the presence of lifetime depressive symptoms and a diagnosis of psychotic depression. Identification of suicide risk factors is essential for successful suicide prevention. While previous research highlights the importance of cigarette smoking as an important risk factor for suicidal behaviors including in patients with psychosis, these results must be interpreted within the context of methodological issues. Crown Copyright & 2013 Published by Elsevier Ireland Ltd. All rights reserved.
Keywords: Suicide Suicide risk factors Cigarette smoking and suicide Psychosis and suicide
1. Introduction The risk of suicide is elevated in patients with psychotic disorders; for example, research indicates that up to 50% of people with schizophrenia attempt suicide and between 5% and 18% die by suicide (Siris, 2001). Known risk factors for suicide within the context of schizophrenia include generic factors such as male gender, younger age, single status, social isolation, history of substance abuse, past suicide attempts; and illness-related factors such as hopelessness, high level of premorbid functioning, recent loss or rejection, post psychotic depression, and insight (Hawton et al., 2005; Hor and Taylor, 2010; Pompili et al., 2007).
n
Corresponding author. Tel.: þ 61 49392900; fax: þ61 49392901. E-mail addresses: [email protected], [email protected], [email protected] (A. Sankaranarayanan), [email protected] (S. Mancuso), [email protected] (D. Castle). 1 Present address: Senior Consultant Psychiatrist and Director Geriatric Fellowship Program, Department of Geriatrics, Hamad Medical Corporation, PO Box 3050, Doha, Qatar. Tel.: þ974 44384530; fax: þ 974 44328224. 2 Tel.: þ61 3 9288 4577; fax: þ 61 3 9288 4802. 3 Tel.: þ61 3 9288 4751; fax: þ61 3 9288 4802.
Smoking has received much attention recently as an independent risk factor for suicide; evidence for this comes from both population based studies (Iwasaki et al., 2005; Tanskanen et al., 2008) and studies in specific high risk groups such as nurses (Hemenway et al., 1993), army personnel (Miller et al., 2000) and psychiatric patients (Malone et al., 2003). Further, a dosedependent increase in risk has been described, with the risk being higher in those who smoke more than 20 cigarettes per day (Beratis et al., 1997; Miller et al., 2000). It has been hypothesized that the reduced brain serotonin function in smokers is associated with impulsive/aggressive traits and therefore increased suicide risk (Malone et al., 2003). Other plausible explanations include lowering of monoamine oxidase activity (Whitfield et al., 2000), antidepressant effects of smoking and possibly insomnia secondary to smoking (Hughes, 2008). Although the association between smoking and suicidality was first described nearly 4 decades ago (Doll and Peto, 1976), earlier researchers minimized the relevance by interpreting the association as an artefact from observational epidemiology. Authors argued that this finding could be accounted for by confounders and therefore should not be taken too seriously (Smith et al., 1992).
0165-1781/$ - see front matter Crown Copyright & 2013 Published by Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.psychres.2013.12.032
A. Sankaranarayanan et al. / Psychiatry Research 215 (2014) 634–640
Patients with schizophrenia and schizoaffective disorder are more likely (up to three times) to smoke than the general population (Kelly and McCreadie, 1999; Etter et al., 2004) and the prevalence can be as high as 90% (Glassman, 1993). These patients also smoke more cigarettes than those in the general population, smoke cigarettes with higher levels of nicotine and tar (O’Farrell et al., 1983) and are less likely to quit (Kelly and McCreadie, 2000). Such associations have also been reported for bipolar disorder and major depressive disorders (Lasser et al., 2000; Dickerson et al., 2013). Ziedonis and Williams (2003) have summarized the numerous biological, psychological and social factors that may act to increase the risk of nicotine dependence among people with psychotic disorders. Smoking is associated with adverse mental and physical consequences among people with psychotic disorders, including dysphoria (Wilhelm, 1998) and increased mortality secondary to smoking related diseases (Lawrence et al., 2001). Smoking has also been recently shown to be related to higher suicide risk in patients with psychiatric disorders (Malone et al., 2003), schizophrenia (Iancu et al., 2006) and bipolar disorder (Ostacher et al., 2006; Goldstein et al., 2008), but few studies have included all these diagnostic groups. Overall, extant studies are limited, inter alia, by small sample size (Ostacher et al., 2006), limited number of variables studied (Iancu et al., 2006; Ostacher et al., 2006) and a specific focus on the association of smoking and serotonin as it relates to suicidality (Malone et al., 2003). Further, it is difficult to make meaningful sense of the literature when conflicting reports have also been published (Kim et al., 2010). In order to understand better the association between smoking and suicidality in patients with psychosis, an ideal study should have sufficient statistical power; should include a range of diagnostic groups, not just schizophrenia; and include a wide range of variables that have been associated with suicidality in previous studies. To this end, we employed a large representative database of Australians with a range of psychotic disorders to assess (i) whether the increased risk of suicidal ideation and attempts pertains across diagnostic groupings, and (ii) whether the risk pertains even after controlling for other known risk factors for suicide. We hypothesized that the risk of suicidality would be higher in current and former smokers and, further, higher in current smokers compared to former smokers across diagnostic groups. We also hypothesized that the amount of daily cigarettes consumed would be associated with severity of suicidal behavior (i.e., number of suicidal attempts and current suicidal ideation).
2. Methods 2.1. Participants We included data from 1812 of the 1825 participants who took part in the Survey of High Impact Psychosis (SHIP) for whom smoking data were available. The SHIP is the second Australian national survey of psychosis and covered seven catchment areas with a total area of 62,000 km2 and a population of 1.5 million people aged between 18 and 64 years. A two-phase design was used. In phase I, potential participants were screened for psychosis during March 2010. In phase 2, 2000 individuals aged 18–64 years were randomly selected for interview from those who screened positive for psychosis. The study was approved by institutional human research ethics committee at each of the seven study sites and all participants provided written, informed consent. While a detailed description of the sample, methods and aims of the SHIP survey can be found elsewhere (Morgan et al., 2012), Table 1 presents the demographic characteristics of the present sample.
2.2. Demographic and clinical variables For our current study, we used the following data, based on our review of the literature and determined prior to analyses being undertaken.
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Table 1 Demographic characteristics of the sample.
Sex Male Female Age Relationship status Single, never married Married or defacto Separated, divorced, or widowed
n or M
% or S.D.
1708 734
59.5% 40.5%
38.39
11.14
1110 309 393
61.3% 17.1% 21.7%
Education Left school no qualification Secondary school qualification Post-secondary school qualification
615 304 891
34.0% 16.8% 49.2%
Employment Employed Unpaid activitya or retired No formal activity or unemployed
595 258 959
32.8% 14.2% 52.9%
1140 318 81 273
62.9% 17.6% 4.5% 15.1%
ICD-10 diagnoses Schizophrenia or schizoaffective disorder Bipolar (Mania) Psychotic depression Other psychosisb Notes: N ¼1812. a
Volunteer work, home duties, or student. Delusions and non-organic psychoses, depression without psychoses, or screened positive for psychosis but did meet criteria for a psychoses diagnosis. b
2.2.1. Socio-demographic information Participant0 s age at time of interview, gender, highest level of education achieved and employment in the previous 12 months, current marital status, the quality of socializing in the previous year and perceived loneliness. 2.2.2. Smoking variables Participants were asked whether they had ever regularly (smoked most days) smoked cigarettes, tobacco, cigars or a pipe, and if they had, whether they had smoked in the previous 4 weeks. Participants were categorized as having never been a regular smoker, being an ex-smoker (not smoked in the previous 4 weeks) or a current smoker (smoked in the previous 4 weeks). Those who reported ever regularly smoking were asked the age they started smoking regularly, their heaviest ever daily cigarette use, and whether they had ever tried to quit smoking for at least 24 h. Those who tried to quit were asked how many times they had tried to quit, times since last quit attempt, longest time ever that they did not smoke (in weeks) and whether they had ever sought help to quit smoking. 2.2.3. Psychopathology and psychiatric history Measures of psychopathology and psychiatric history were determined using the Diagnostic Interview for Psychosis (DIP) (Castle et al., 2006). We included those clinical measures that have been associated with suicidal risk from previous research, including: the presence of active and/or lifetime psychotic experiences (delusions and hallucinations), post psychotic depression, comorbid chronic physical illness, extra-pyramidal medication side effects, agitation and motor restlessness, polypharmacy and insight. We also included information on mode of onset of illness, chronicity of illness, hospitalization history, negative attitudes towards medication, fear of further mental deterioration; deteriorating health with high levels of premorbid functioning; and early signs of disturbed psychosocial adjustment. 2.2.4. Substance use Alcohol dependence in the previous 12 months was assessed using the Alcohol Use Disorders Identification Test (AUDIT) (Babor et al., 2001). Probable alcohol dependence was identified as having an AUDIT score of 20 or above. Abuse of, or dependence on, cannabis and other drugs in the previous 12 months was assessed using the DIP (Castle et al., 2006). The corresponding items were adapted from the 10-item Drug Abuse Screening Test (DAST-10) (Skinner, 1982). 2.2.5. Suicidality Suicidal ideation (current, past year, and lifetime) was assessed using the corresponding items in the DIP (Castle et al., 2006), which were adapted from the Operational Criteria Checklist for Psychosis (McGuffin et al., 1991; Williams et al., 1996) and the World Health Organization Schedules for Clinical Assessment in
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Neuropsychiatry (Wing et al., 1990). The specific questions were “Have you ever felt that life was not worth living?”; “Have you thought about harming yourself or even made an attempt at suicide?”; and qualifier questions such as “What happened? When was this?” and “How long did you feel like this?” Suicidal ideation was rated as present if the participant reported the presence of suicidal ideation lasting at least 1 week or an actual suicide attempt in the previous 4 weeks (current), past year, or in their lifetime. The DIP was also used to rate the presence of a lifetime suicide attempt and any occasions of deliberate self-harm in the previous 12 months, including overdose. The self-harm items were adapted from the Australian Second National Survey of Mental Health and Wellbeing 2007 (Slade et al., 2009). The specific items were as follows: Rate whether depressed or not if there is:
a persistent intrusive thought, wishing to be dead; or preoccupation with death, not necessarily one0 s own death; a more detailed consideration, thinking of suicide; or planning of possible techniques, or actual attempts at suicide.
Do not rate:
A rare fleeting thought or non suicidal self-harming behavior. Self harming behavior outside the context of suicidal ideation or intent. 2.3. Statistical analysis Analyses were conducted using Stata version 12.1 (StataCorp, College Station, Texas, USA). Means and standard deviations were calculated for continuous variables, while frequencies were measured for categorical variables. A series of univariate logistic regression models predicting lifetime suicide attempts were conducted to select the covariate predictors. Variables were retained for the multiple logistic regression models if they were a significant predictor of lifetime suicide attempts. As recommended by Vittinghoff et al. (2011), predictor variables significant at p o0.20 were also retained to control for potential confounding effects. A series of multiple logistic regressions were then conducted to predict lifetime suicide attempts using current smoking status and lifetime smoking status as the independent variables, respectively, while controlling for the retained predictor variables. Missing values were excluded on a listwise basis. For each model, independent variables were systematically evaluated for second-order interactions and the degree of association among correlates. No significant interaction effects were found. For all analyses, a value of p o0.05 was considered statistically significant unless otherwise stated.
3. Results 1207 participants were current smokers and 258 were former smokers. Among participants for whom smoking data was available, 904 (50%) had attempted suicide of which 628 (70.1%) were current smokers. 1222 (67%) had lifetime suicidal ideation, of whom 922 (81.2%) had a lifetime history of smoking. Table 2 presents the descriptive statistics for the predictor variables used in the multiple regression modeling. Although important, we did not include variables that were non-significant predictors of lifetime suicide attempt or lifetime suicide ideation such as age when the person started smoking (OR 1.01; p¼ 0.205 for lifetime suicidal ideation and OR 1.01; p¼ 0.305 for lifetime suicide attempt) or number of quit attempts (OR 1.01; p ¼0.180 for lifetime suicide attempt and OR 1.00; p ¼0.691 for lifetime suicide ideation). This was in keeping with our stated methodology of retaining predictor variables significant at p o0.20 for potential confounding effects. The univariate analyses for current smoking status indicated that current smokers were 1.4 times more likely to have reported a lifetime suicide attempt than non-smokers. In relation to lifetime smoking status, individuals who had never smoked were 0.7 times less likely to have reported a lifetime suicide attempt relative to current smokers, while former smokers were 0.8 times less likely than current smokers to have reported a lifetime suicide attempt. The number of cigarettes smoked daily was not significantly associated with any lifetime suicide attempts (OR ¼1.00, 95% CI ¼0.99, 1.01, p ¼ 0.189), any current suicidal ideation (OR¼ 1.00,
Table 2 Descriptive statistics for the independent variables and covariates. n or M
% or S.D.
Current smoking status Smoker Non-smoker
1207 605
66.6% 33.4%
Lifetime smoking status Never smoked Former smoker Current smoker
347 258 1207
19.2% 14.2% 66.6%
352 573 441 403
19.9% 32.4% 24.9% 22.8%
1293 467 503 482 913 299
71.4% 25.8% 27.8% 26.6% 50.4% 16.5%
687 577 548
35.9% 31.8% 30.2%
Perceived loneliness (n¼ 1769) None Somewhat lonely Lonely Very lonely Gradual or insidious illness onset Perceived uncontrolled symptoms of mental illness Any persecutory delusions (current) Substance abuse/dependence (lifetime) Alcohol abuse/dependence (lifetime) Any deliberate self-harm in past year Course of illness Good recovery Partial recovery Chronic Any depressive symptoms (lifetime) Any depressive symptoms (current) Comorbid physical illness (lifetime) Number of lifetime medical conditions Lack of insight (lifetime) Psychiatric inpatient admission in past year Deterioration from premorbid level of functioning Poor premorbid work adjustment Poor premorbid social adjustment Premorbid personality disorder Polypharmacy Number of psychotropic medications
1459 524 1527 2.96 430 631 1638 564 651 245 453 1.94
80.5% 28.9% 84.3% 2.60 23.7% 34.8% 90.4% 31.1% 35.9% 13.5% 25.0% 1.19
Note: N ¼ 1812 unless otherwise stated.
95% CI ¼ 0.99, 1.02, p ¼0.558), or any lifetime suicidal ideation (OR¼ 1.00, 95% CI ¼0.99, 1.01, p ¼0.566), respectively (Table 3). When adding the covariates to the logistic regression model, however, current smoking status lost its statistical significance (see Table 4). The strongest predictors were self-harm in the previous 12 months, the presence of lifetime depressive symptoms, a diagnosis of psychotic depression and alcohol abuse.
4. Discussion Identification of suicide risk factors is essential to plan and implement successful risk reduction strategies. As highlighted earlier, smoking has received attention recently as an independent risk factor for subsequent suicide, including in patients with psychotic illness. Bolton and Robinson (2010) calculated the Population Attributable Fraction (PAF) for a range of risk factors for suicidality, and concluded that 8% of all suicide attempts could be attributed to smoking. Smoking along with major depressive disorder, borderline personality disorder, nicotine dependence and post-traumatic stress disorder accounted for 60% of all suicidal attempts in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) database. Interestingly, our own study yielded mixed results. While univariate analysis indicated that current smokers were 1.4 times more likely (than those who never smoked) to have attempted suicide in their lifetime, adding other covariates to the logistic regression model reduced this association to non-significance. The strongest predictors for suicide attempt in our cohort were
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Table 3 Series of univariate logistic regressions predicting lifetime suicide attempts. OR
SE
95% CI
Female Education No secondary school qualificationa Completed secondary schooling Post-secondary school qualification
1.68nnn
0.16
(1.39–2.03)
0.73n 0.76nn
0.10 0.08
(0.55–0.97) (0.61–0.93)
Perceived loneliness Nonea Somewhat lonely Lonely Very lonely
1.49nn 1.78nnn 1.98nnn
0.21 0.23 0.30
(1.13–1.95) (1.34–2.37) (1.48–2.67)
Employment status Paid employmenta Unpaid activity or retirement No formal activity
1.64nn 1.29n
0.25 0.14
(1.22–2.20) (1.05–1.59)
Current marital status Single, never marrieda Married or defacto Separated, divorced, or widowed
1.49nn 1.73nnn
0.19 0.21
(1.16–1.93) (1.37–2.19)
Gradual or insidious illness onset Uncontrolled symptoms of mental illness Persecutory delusions (current) Substance abuse/dependence (lifetime) Alcohol abuse/dependence (lifetime) Any deliberate self-harm in past year
1.42nn 1.08nnn 1.31n 1.22 þ 1.73nnn 9.16nnn
0.15 0.02 0.14 0.13 0.16 1.64
(1.16–1.75) (1.05–1.11) (1.06–1.61) (0.99–1.50) (1.44–2.09) (6.36–12.85)
Course of illness Good recoverya Partial recovery Chronic
1.78nnn 1.68nnn
0.20 0.19
(1.42–2.23) (1.34–2.11)
Any depressive symptoms (lifetime) Any depressive symptoms (current) Comorbid physical illness (lifetime) Number of lifetime medical conditions Lack of insight (lifetime) Psychiatric inpatient admission in past year Deterioration from premorbid level of functioning Poor premorbid work adjustment Poor premorbid social adjustment Premorbid personality disorder Polypharmacy Number of psychotropic medications
3.38nnn 1.69nnn 1.54nn 1.16nnn 0.68nnn 1.30nn 1.49n 1.38nn 1.85nnn 1.84nnn 1.20 þ 1.29nnn
0.45 0.18 0.20 0.02 0.08 0.13 0.24 0.14 0.18 0.26 0.13 0.05
(2.61–4.38) (1.38–2.08) (1.19–1.99) (1.12–1.21) (0.55–0.84) (1.07–1.58) (1.08–2.05) (1.13–1.69) (1.52–2.25) (1.39–2.42) (0.97–1.49) (1.19–1.40)
ICD-10 diagnosis Schizophrenia/schizoaffectivea Bipolar (mania) Psychotic depression Other psychoses Current smoker
1.28 þ 3.03nnn 1.24 þ 1.37nn
0.16 0.78 0.17 0.14
(0.99–1.64) (1.83–5.02) (0.96–1.62) (1.12–1.66)
0.72nn 0.75n
0.09 0.10
(0.56–0.91) (0.57–0.98)
Lifetime smoking status Never smoked Former smoker Current smokera
Note: N ¼ 1797 unless otherwise stated. a
Reference category. p o 0.20. p o 0.05. nn p o 0.01. nnn p o 0.001. þ
n
self-harm in the previous 12 months, lifetime depressive symptoms, and a diagnosis of psychotic depression. Our hypotheses that the risk of suicidality would be higher in current and former smokers were not supported. We also hypothesized that the amount of daily cigarettes smoked would be associated with severity of suicidal behavior; in other words, we were looking for a dose–response relationship in severity of suicidal behaviors. However, number of cigarettes
smoked daily was not a significant predictor of lifetime suicide attempt, current suicidal ideation, or lifetime suicidal ideation respectively. Previous studies that have found a dose–response relationship between smoking and suicidal risk were conducted in the general population. Studies done in mentally ill patients that have reported such an association (e.g. Goldstein et al., 2008) also concluded that this association was reduced on regression analysis.
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Table 4 Multiple logistic regression predicting lifetime suicide attempts for current and lifetime smoking status. Current smoking status
Lifetime smoking status
OR
SE
95% CI
OR
SE
95% CI
Female
1.36n
0.17
(1.06–1.74)
1.36n
0.17
(1.06–1.73)
Education No secondary school qualificationa Completed secondary schooling Post-secondary school qualification
0.90 0.81
0.15 0.10
(0.65–1.25) (0.63–1.04)
0.90 0.81
0.15 0.10
(0.65–1.25) (0.63–1.04)
Perceived loneliness Nonea Somewhat lonely Lonely Very lonely
1.17 1.05 0.96
0.18 0.18 0.17
(0.86–1.59) (0.75–1.47) (0.67–1.36)
1.17 1.05 0.95
0.18 0.18 0.17
(0.86–1.59) (0.75–1.47) (0.67–1.36)
Employment status Paid employmenta Unpaid activity or retirement No formal activity
1.53n 1.07
0.27 0.14
(1.08–2.17) (0.83–1.39)
1.53* 1.07
0.27 0.14
(1.08–2.17) (0.83–1.39)
Current marital status Single, never marrieda Married or defacto Separated, divorced, or widowed
1.22 1.43n
0.19 0.21
(0.89–1.66) (1.08–1.90)
1.22 1.43n
0.19 0.21
(0.90–1.67) (1.08–1.90)
Gradual or insidious illness onset Uncontrolled symptoms of mental illness Persecutory delusions (current) Substance abuse/dependence (lifetime) Alcohol abuse/dependence (lifetime) Any deliberate self-harm in past year
1.24 1.03 1.15 1.03 1.68nnn 7.52nnn
0.15 0.02 0.15 0.14 0.20 1.50
(0.97–1.58) (0.99–1.06) (0.89–1.50) (0.79–1.34) (1.33–2.12) (5.09–11.10)
1.24 1.03 1.15 1.03 1.69nnn 7.51nnn
0.15 0.02 0.15 0.14 0.20 1.49
(0.97–1.58) (0.99–1.06) (0.89–1.50) (0.79–1.35) (1.33–2.14) (5.08–11.08)
Course of illness Good recoverya Partial recovery Chronic
1.38n 1.37n
0.19 0.20
(1.06–1.79) (1.02–1.84)
1.38n 1.37n
0.19 0.20
(1.06–1.79) (1.02–1.84)
Any depressive symptoms (lifetime) Any depressive symptoms (current) Comorbid physical illness (lifetime) Number of lifetime medical conditions Lack of insight (lifetime) Psychiatric inpatient admission in past year Deterioration from premorbid level of functioning Poor premorbid work adjustment Poor premorbid social adjustment Premorbid personality disorder Polypharmacy Number of psychotropic medications
2.43nnn 0.82 0.83 1.06* 0.80 0.84 0.94 1.06 1.52nn 1.08 1.02 1.19nn
0.39 0.11 0.15 0.03 0.11 0.10 0.19 0.14 0.20 0.20 0.16 0.07
(1.78–3.32) (0.63–1.07) (0.59–1.18) (1.01–1.12) (0.61–1.05) (0.66–1.06) (0.63–1.39) (0.82–1.36) (1.17–1.98) (0.75–1.56) (0.76–1.38) (1.06–1.33)
2.43nnn 0.82 0.83 1.06n 0.80 0.83 0.94 1.06 1.52nn 1.08 1.02 1.19nn
0.39 0.11 0.15 0.03 0.11 0.10 0.19 0.14 0.20 0.20 0.16 0.07
(1.78–3.32) (0.63–1.07) (0.59–1.17) (1.01–1.12) (0.61–1.05) (0.65–1.06) (0.63–1.39) (0.82–1.36) (1.17–1.98) (0.75–1.56) (0.76–1.38) (1.06–1.33)
ICD-10 diagnosis Schizophrenia/schizoaffectivea Bipolar (mania) Psychotic depression Other psychoses Current smoker
0.90 1.89n 0.96 1.27
0.15 0.56 0.16 0.16
(0.66–1.24) (1.06–3.40) (0.69–1.32) (0.99–1.63)
0.91 1.90n 0.96 –
0.15 0.57 0.16 –
(0.66–1.24) (1.06–3.40) (0.69–1.32) –
–
–
– 0.81 0.77
0.13 0.13
(0.59–1.11) (0.56–1.06)
0.11nnn
0.03
(0.06–0.20)
Lifetime smoking status Never smoked Former smoker Current smokera Constant
0.09nnn
0.03
(0.05–0.16)
Note: N ¼ 1741. a
Reference category. po 0.05. nn p o0.01. nnn p o0.001. n
Dose response relationship indicates some form of biological changes; changes that are particularly important with regards the smoking-mental illness-suicide paradigm include changes in neurochemistry (e.g. serotonin levels) (Hughes, 2008) and/or neurobiological changes (e.g., changes to orbito-frontal cortex or anterior cingulate cortex, areas implicated in increased impulsivity
and poor social-problem-solving) (Shamay-Tsoory et al., 2006; Heberlein et al., 2008). Patients with mental illness, particularly schizophrenia or schizoaffective disorders, are also associated with these changes and in fact, these may be part of the core psychopathology of the illness. It is therefore likely that any association between smoking and these changes becomes less
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evident in this group. This probably explains the absence of statistically significant findings in our group of patients and a number of previous studies that have reported similar findings. One of the major strengths of our study was that we had data on most of the known risk factors for suicide and employed it in multivariate analysis. While this study was a secondary data analysis, we had sufficient sample size to rule out type II error. As we had 299 participants with history of self-harm, with the proportion of smoking being 66.1%, and keeping the alpha as 0.05 and the relative risk at a modest 1.8 for suicidal attempts (based on a recent meta-analysis by Li et al. (2012) for completed suicide), this would give us a power of 0.89. Further, our sample comprised of Australians with a range of psychotic disorders, which provided the opportunity to study interaction effects among the different diagnostic groups; we did not find any interaction effects, suggesting that the same factors operate irrespective of diagnostic grouping. At the same time, it could be argued that there is the risk of “over-adjustment” particularly when smoking contributes to many of the risk factors adjusted for (Leistikow, 2003). The present study must be interpreted in the context of several limitations. This study was not primarily conducted to study the association between suicidal risk and smoking among patients with psychotic disorders. Hughes (2008), in his review, suggests that an ideal study investigating any association between smoking and suicidal risk should include measures of all the major risk factors for suicide and distinguish between confounders and mediators. However, such a study would be very difficult to design and/or conduct as it would require follow-up of a large cohort to study the many possible interactions between ongoing smoking, stopping smoking and taking medications. Secondly, we did not measure for any specific markers for impulsivity. Our study selection and timing of recruitment may not be representative of an acute sample, which is when the suicidal risk is highest, particularly in patients with schizophrenia (Harkavy-Friedman et al., 1999). This would, however, be less pertinent given that we wanted to study the risk cigarette smoking contributed to suicide or suicidal behaviors in patients with psychotic disorders. In order to understand how smoking might be associated with suicide, it is important to know how smoking is associated with mental illness. It has been suggested that mentally ill patients use cigarettes as a means of self-medication of psychiatric symptoms (Carmody, 1992; Addington et al., 1998). This could be interpreted as cigarette smoking having antidepressant or anxiolytic properties, such as the energizing effects of antidepressants (Teicher et al., 1993). That is, nicotine induced antidepressant effects may account for chronic insomnia and a feeling of being energized and this may precipitate suicidal attempts. An alternative view is that antecedent smoking is associated with increased risk of depression. In his review, Hughes (2008) concludes that current smoking could be associated with suicide due to third factors or confounders. This is plausible because many of the risk factors for suicide are also risk factors for being a smoker as we found in our sample. While the influence of confounders could be tested out using covariate analysis, it is also possible that the findings from previous studies may be inaccurate because the most important confounders were not included or because what was classified as confounders may be potential mediators (Breslau et al., 2005). Finally, it is likely that the same underlying factors may predispose to smoking and mental health problems (Breslau et al., 1998). 4.1. Conclusion Suicide rates among patients with schizophrenia patients remain high. Mental health professionals are often faced with what has been labeled “double trouble” (Magura, 2008), the cooccurrence of mental illness and substance use, and both factors
639
that increase the risk of suicide (Cardoso et al., 2008; Goldstein et al., 2008; Shantna et al., 2009). Secondary prevention focuses on state-dependent risk factors that can potentially be modified, including substance use (Pompili et al., 2007). While cigarette smoking has been identified as an important independent risk factor for suicide among patients with mental illness, this was not supported by our findings. It is likely that this is due to smoking being an intermediary between other more pertinent risk factors and suicide or suicidal attempts. That is, those patients who are more distressed or disabled are more likely to smoke. While smoking is associated with an increase in suicidal risk, this risk becomes less significant in those who have mental illness. This is nevertheless an important area of study. Future research should compare the suicide risk among smokers in those with and without a mental illness. There is also a need for prospective studies that focuses on the association of smoking and suicide a priori, includes as many possible confounders, and mediators and examine the effects of suicide outcomes with attempts and success of smoking cessation.
Role of funding sources This publication is based on data collected in the framework of the 2010 Australian National Survey of High Impact Psychosis. The members of the Survey of High Impact Psychosis Study Group are: V. Morgan (National Project Director), A. Jablensky (Chief Scientific Advisor), A. Waterreus (National Project Coordinator), R. Bush, V. Carr, D. Castle, M. Cohen, C. Galletly, C. Harvey, B. Hocking, A. Mackinnon, P. McGorry, J. McGrath, A. Neil, S. Saw, H. Stain. The study was funded by the Australian Government Department of Health and Ageing.
Contributors All authors contributed to the writing of this manuscript. While analysis was performed by the second author, all authors contributed to the interpretation of the results. Drafting of the manuscript was performed by the first author and contributed partly by the remaining authors.
Acknowledgments This report acknowledges, with thanks, the hundreds of mental health professionals who participated in the preparation and conduct of the survey and the many Australians with psychotic disorders who gave their time and whose responses form the basis of this publication. References Addington, J., El-Guebaly, N., Campbell, W., Hodgins, D.C., Addington, D., 1998. Smoking cessation treatment for patients with schizophrenia. American Journal of Psychiatry 155 (7), 974–975. Babor, T., Higgins-Biddle, J., Saunders, J., Monteiro, M., 2001. The Alcohol Use Disorders Identification Test: Guidelines for use in Primary Care, 2 ed. World Health Organization, Geneva. Beratis, S., Lekka, N.P., Gabriel, J., 1997. Smoking among suicide attempters. Comprehensive Psychiatry 38 (2), 74–79. Bolton, J.M., Robinson, J., 2010. Population-attributable fractions of Axis I and Axis II mental disorders for suicide attempts: findings from a representative sample of the adult, noninstitutionalized US population. American Journal of Public Health 100 (12), 2473. Breslau, N., Schultz, L.R., Johnson, E.O., Peterson, E.L., Davis, G.C., 2005. Smoking and the risk of suicidal behavior: a prospective study of a community sample. Archives of General Psychiatry 62 (3), 328.
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Psychiatry Research journal homepage: www.elsevier.com/locate/psychres
Smoking and suicidality in patients with a psychotic disorder Anoop Sankaranarayanan a,n,1, Serafino Mancuso b,2, David Castle c,d,3 a
Hunter Valley Mental Health Service, 10/555 High Street, Maitland, NSW 2320, Australia St Vincent0 s Mental Health, PO Box 2900, Fitzroy, VIC 3065, Australia St. Vincent0 s Hospital Melbourne, Australia d Department of Psychiatry, University of Melbourne, Australia b c
art ic l e i nf o
a b s t r a c t
Article history: Received 11 April 2013 Received in revised form 4 December 2013 Accepted 16 December 2013 Available online 24 December 2013
Cigarette smoking has been associated with an increased risk of suicide. Patients with psychosis are more likely to smoke cigarettes and are also at an increased risk of suicide. The aim of this study was to compare risk for suicidal behavior among patients with psychosis who were current smokers, previous smokers and nonsmokers. We studied 1812 of the 1825 participants who took part in the Australian Survey of High Impact Psychosis (SHIP) for whom smoking data was available. We identified predictors for lifetime suicide attempts using univariate logistic regression analysis. These variables were retained for the multiple logistic regression models if they were a significant predictor of lifetime suicide attempts. A series of multiple logistic regressions were then conducted to predict lifetime suicide attempts using current smoking status and lifetime smoking status as independent variables, respectively, while controlling for the retained predictor variables. Current smoking and lifetime smoking were statistically significant predictors of lifetime suicide attempts. However adding the covariates to a logistic regression model reduced this association to non-significance. The strongest predictors were self-harm in the past 12 months, the presence of lifetime depressive symptoms and a diagnosis of psychotic depression. Identification of suicide risk factors is essential for successful suicide prevention. While previous research highlights the importance of cigarette smoking as an important risk factor for suicidal behaviors including in patients with psychosis, these results must be interpreted within the context of methodological issues. Crown Copyright & 2013 Published by Elsevier Ireland Ltd. All rights reserved.
Keywords: Suicide Suicide risk factors Cigarette smoking and suicide Psychosis and suicide
1. Introduction The risk of suicide is elevated in patients with psychotic disorders; for example, research indicates that up to 50% of people with schizophrenia attempt suicide and between 5% and 18% die by suicide (Siris, 2001). Known risk factors for suicide within the context of schizophrenia include generic factors such as male gender, younger age, single status, social isolation, history of substance abuse, past suicide attempts; and illness-related factors such as hopelessness, high level of premorbid functioning, recent loss or rejection, post psychotic depression, and insight (Hawton et al., 2005; Hor and Taylor, 2010; Pompili et al., 2007).
n
Corresponding author. Tel.: þ 61 49392900; fax: þ61 49392901. E-mail addresses: [email protected], [email protected], [email protected] (A. Sankaranarayanan), [email protected] (S. Mancuso), [email protected] (D. Castle). 1 Present address: Senior Consultant Psychiatrist and Director Geriatric Fellowship Program, Department of Geriatrics, Hamad Medical Corporation, PO Box 3050, Doha, Qatar. Tel.: þ974 44384530; fax: þ 974 44328224. 2 Tel.: þ61 3 9288 4577; fax: þ 61 3 9288 4802. 3 Tel.: þ61 3 9288 4751; fax: þ61 3 9288 4802.
Smoking has received much attention recently as an independent risk factor for suicide; evidence for this comes from both population based studies (Iwasaki et al., 2005; Tanskanen et al., 2008) and studies in specific high risk groups such as nurses (Hemenway et al., 1993), army personnel (Miller et al., 2000) and psychiatric patients (Malone et al., 2003). Further, a dosedependent increase in risk has been described, with the risk being higher in those who smoke more than 20 cigarettes per day (Beratis et al., 1997; Miller et al., 2000). It has been hypothesized that the reduced brain serotonin function in smokers is associated with impulsive/aggressive traits and therefore increased suicide risk (Malone et al., 2003). Other plausible explanations include lowering of monoamine oxidase activity (Whitfield et al., 2000), antidepressant effects of smoking and possibly insomnia secondary to smoking (Hughes, 2008). Although the association between smoking and suicidality was first described nearly 4 decades ago (Doll and Peto, 1976), earlier researchers minimized the relevance by interpreting the association as an artefact from observational epidemiology. Authors argued that this finding could be accounted for by confounders and therefore should not be taken too seriously (Smith et al., 1992).
0165-1781/$ - see front matter Crown Copyright & 2013 Published by Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.psychres.2013.12.032
A. Sankaranarayanan et al. / Psychiatry Research 215 (2014) 634–640
Patients with schizophrenia and schizoaffective disorder are more likely (up to three times) to smoke than the general population (Kelly and McCreadie, 1999; Etter et al., 2004) and the prevalence can be as high as 90% (Glassman, 1993). These patients also smoke more cigarettes than those in the general population, smoke cigarettes with higher levels of nicotine and tar (O’Farrell et al., 1983) and are less likely to quit (Kelly and McCreadie, 2000). Such associations have also been reported for bipolar disorder and major depressive disorders (Lasser et al., 2000; Dickerson et al., 2013). Ziedonis and Williams (2003) have summarized the numerous biological, psychological and social factors that may act to increase the risk of nicotine dependence among people with psychotic disorders. Smoking is associated with adverse mental and physical consequences among people with psychotic disorders, including dysphoria (Wilhelm, 1998) and increased mortality secondary to smoking related diseases (Lawrence et al., 2001). Smoking has also been recently shown to be related to higher suicide risk in patients with psychiatric disorders (Malone et al., 2003), schizophrenia (Iancu et al., 2006) and bipolar disorder (Ostacher et al., 2006; Goldstein et al., 2008), but few studies have included all these diagnostic groups. Overall, extant studies are limited, inter alia, by small sample size (Ostacher et al., 2006), limited number of variables studied (Iancu et al., 2006; Ostacher et al., 2006) and a specific focus on the association of smoking and serotonin as it relates to suicidality (Malone et al., 2003). Further, it is difficult to make meaningful sense of the literature when conflicting reports have also been published (Kim et al., 2010). In order to understand better the association between smoking and suicidality in patients with psychosis, an ideal study should have sufficient statistical power; should include a range of diagnostic groups, not just schizophrenia; and include a wide range of variables that have been associated with suicidality in previous studies. To this end, we employed a large representative database of Australians with a range of psychotic disorders to assess (i) whether the increased risk of suicidal ideation and attempts pertains across diagnostic groupings, and (ii) whether the risk pertains even after controlling for other known risk factors for suicide. We hypothesized that the risk of suicidality would be higher in current and former smokers and, further, higher in current smokers compared to former smokers across diagnostic groups. We also hypothesized that the amount of daily cigarettes consumed would be associated with severity of suicidal behavior (i.e., number of suicidal attempts and current suicidal ideation).
2. Methods 2.1. Participants We included data from 1812 of the 1825 participants who took part in the Survey of High Impact Psychosis (SHIP) for whom smoking data were available. The SHIP is the second Australian national survey of psychosis and covered seven catchment areas with a total area of 62,000 km2 and a population of 1.5 million people aged between 18 and 64 years. A two-phase design was used. In phase I, potential participants were screened for psychosis during March 2010. In phase 2, 2000 individuals aged 18–64 years were randomly selected for interview from those who screened positive for psychosis. The study was approved by institutional human research ethics committee at each of the seven study sites and all participants provided written, informed consent. While a detailed description of the sample, methods and aims of the SHIP survey can be found elsewhere (Morgan et al., 2012), Table 1 presents the demographic characteristics of the present sample.
2.2. Demographic and clinical variables For our current study, we used the following data, based on our review of the literature and determined prior to analyses being undertaken.
635
Table 1 Demographic characteristics of the sample.
Sex Male Female Age Relationship status Single, never married Married or defacto Separated, divorced, or widowed
n or M
% or S.D.
1708 734
59.5% 40.5%
38.39
11.14
1110 309 393
61.3% 17.1% 21.7%
Education Left school no qualification Secondary school qualification Post-secondary school qualification
615 304 891
34.0% 16.8% 49.2%
Employment Employed Unpaid activitya or retired No formal activity or unemployed
595 258 959
32.8% 14.2% 52.9%
1140 318 81 273
62.9% 17.6% 4.5% 15.1%
ICD-10 diagnoses Schizophrenia or schizoaffective disorder Bipolar (Mania) Psychotic depression Other psychosisb Notes: N ¼1812. a
Volunteer work, home duties, or student. Delusions and non-organic psychoses, depression without psychoses, or screened positive for psychosis but did meet criteria for a psychoses diagnosis. b
2.2.1. Socio-demographic information Participant0 s age at time of interview, gender, highest level of education achieved and employment in the previous 12 months, current marital status, the quality of socializing in the previous year and perceived loneliness. 2.2.2. Smoking variables Participants were asked whether they had ever regularly (smoked most days) smoked cigarettes, tobacco, cigars or a pipe, and if they had, whether they had smoked in the previous 4 weeks. Participants were categorized as having never been a regular smoker, being an ex-smoker (not smoked in the previous 4 weeks) or a current smoker (smoked in the previous 4 weeks). Those who reported ever regularly smoking were asked the age they started smoking regularly, their heaviest ever daily cigarette use, and whether they had ever tried to quit smoking for at least 24 h. Those who tried to quit were asked how many times they had tried to quit, times since last quit attempt, longest time ever that they did not smoke (in weeks) and whether they had ever sought help to quit smoking. 2.2.3. Psychopathology and psychiatric history Measures of psychopathology and psychiatric history were determined using the Diagnostic Interview for Psychosis (DIP) (Castle et al., 2006). We included those clinical measures that have been associated with suicidal risk from previous research, including: the presence of active and/or lifetime psychotic experiences (delusions and hallucinations), post psychotic depression, comorbid chronic physical illness, extra-pyramidal medication side effects, agitation and motor restlessness, polypharmacy and insight. We also included information on mode of onset of illness, chronicity of illness, hospitalization history, negative attitudes towards medication, fear of further mental deterioration; deteriorating health with high levels of premorbid functioning; and early signs of disturbed psychosocial adjustment. 2.2.4. Substance use Alcohol dependence in the previous 12 months was assessed using the Alcohol Use Disorders Identification Test (AUDIT) (Babor et al., 2001). Probable alcohol dependence was identified as having an AUDIT score of 20 or above. Abuse of, or dependence on, cannabis and other drugs in the previous 12 months was assessed using the DIP (Castle et al., 2006). The corresponding items were adapted from the 10-item Drug Abuse Screening Test (DAST-10) (Skinner, 1982). 2.2.5. Suicidality Suicidal ideation (current, past year, and lifetime) was assessed using the corresponding items in the DIP (Castle et al., 2006), which were adapted from the Operational Criteria Checklist for Psychosis (McGuffin et al., 1991; Williams et al., 1996) and the World Health Organization Schedules for Clinical Assessment in
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Neuropsychiatry (Wing et al., 1990). The specific questions were “Have you ever felt that life was not worth living?”; “Have you thought about harming yourself or even made an attempt at suicide?”; and qualifier questions such as “What happened? When was this?” and “How long did you feel like this?” Suicidal ideation was rated as present if the participant reported the presence of suicidal ideation lasting at least 1 week or an actual suicide attempt in the previous 4 weeks (current), past year, or in their lifetime. The DIP was also used to rate the presence of a lifetime suicide attempt and any occasions of deliberate self-harm in the previous 12 months, including overdose. The self-harm items were adapted from the Australian Second National Survey of Mental Health and Wellbeing 2007 (Slade et al., 2009). The specific items were as follows: Rate whether depressed or not if there is:
a persistent intrusive thought, wishing to be dead; or preoccupation with death, not necessarily one0 s own death; a more detailed consideration, thinking of suicide; or planning of possible techniques, or actual attempts at suicide.
Do not rate:
A rare fleeting thought or non suicidal self-harming behavior. Self harming behavior outside the context of suicidal ideation or intent. 2.3. Statistical analysis Analyses were conducted using Stata version 12.1 (StataCorp, College Station, Texas, USA). Means and standard deviations were calculated for continuous variables, while frequencies were measured for categorical variables. A series of univariate logistic regression models predicting lifetime suicide attempts were conducted to select the covariate predictors. Variables were retained for the multiple logistic regression models if they were a significant predictor of lifetime suicide attempts. As recommended by Vittinghoff et al. (2011), predictor variables significant at p o0.20 were also retained to control for potential confounding effects. A series of multiple logistic regressions were then conducted to predict lifetime suicide attempts using current smoking status and lifetime smoking status as the independent variables, respectively, while controlling for the retained predictor variables. Missing values were excluded on a listwise basis. For each model, independent variables were systematically evaluated for second-order interactions and the degree of association among correlates. No significant interaction effects were found. For all analyses, a value of p o0.05 was considered statistically significant unless otherwise stated.
3. Results 1207 participants were current smokers and 258 were former smokers. Among participants for whom smoking data was available, 904 (50%) had attempted suicide of which 628 (70.1%) were current smokers. 1222 (67%) had lifetime suicidal ideation, of whom 922 (81.2%) had a lifetime history of smoking. Table 2 presents the descriptive statistics for the predictor variables used in the multiple regression modeling. Although important, we did not include variables that were non-significant predictors of lifetime suicide attempt or lifetime suicide ideation such as age when the person started smoking (OR 1.01; p¼ 0.205 for lifetime suicidal ideation and OR 1.01; p¼ 0.305 for lifetime suicide attempt) or number of quit attempts (OR 1.01; p ¼0.180 for lifetime suicide attempt and OR 1.00; p ¼0.691 for lifetime suicide ideation). This was in keeping with our stated methodology of retaining predictor variables significant at p o0.20 for potential confounding effects. The univariate analyses for current smoking status indicated that current smokers were 1.4 times more likely to have reported a lifetime suicide attempt than non-smokers. In relation to lifetime smoking status, individuals who had never smoked were 0.7 times less likely to have reported a lifetime suicide attempt relative to current smokers, while former smokers were 0.8 times less likely than current smokers to have reported a lifetime suicide attempt. The number of cigarettes smoked daily was not significantly associated with any lifetime suicide attempts (OR ¼1.00, 95% CI ¼0.99, 1.01, p ¼ 0.189), any current suicidal ideation (OR¼ 1.00,
Table 2 Descriptive statistics for the independent variables and covariates. n or M
% or S.D.
Current smoking status Smoker Non-smoker
1207 605
66.6% 33.4%
Lifetime smoking status Never smoked Former smoker Current smoker
347 258 1207
19.2% 14.2% 66.6%
352 573 441 403
19.9% 32.4% 24.9% 22.8%
1293 467 503 482 913 299
71.4% 25.8% 27.8% 26.6% 50.4% 16.5%
687 577 548
35.9% 31.8% 30.2%
Perceived loneliness (n¼ 1769) None Somewhat lonely Lonely Very lonely Gradual or insidious illness onset Perceived uncontrolled symptoms of mental illness Any persecutory delusions (current) Substance abuse/dependence (lifetime) Alcohol abuse/dependence (lifetime) Any deliberate self-harm in past year Course of illness Good recovery Partial recovery Chronic Any depressive symptoms (lifetime) Any depressive symptoms (current) Comorbid physical illness (lifetime) Number of lifetime medical conditions Lack of insight (lifetime) Psychiatric inpatient admission in past year Deterioration from premorbid level of functioning Poor premorbid work adjustment Poor premorbid social adjustment Premorbid personality disorder Polypharmacy Number of psychotropic medications
1459 524 1527 2.96 430 631 1638 564 651 245 453 1.94
80.5% 28.9% 84.3% 2.60 23.7% 34.8% 90.4% 31.1% 35.9% 13.5% 25.0% 1.19
Note: N ¼ 1812 unless otherwise stated.
95% CI ¼ 0.99, 1.02, p ¼0.558), or any lifetime suicidal ideation (OR¼ 1.00, 95% CI ¼0.99, 1.01, p ¼0.566), respectively (Table 3). When adding the covariates to the logistic regression model, however, current smoking status lost its statistical significance (see Table 4). The strongest predictors were self-harm in the previous 12 months, the presence of lifetime depressive symptoms, a diagnosis of psychotic depression and alcohol abuse.
4. Discussion Identification of suicide risk factors is essential to plan and implement successful risk reduction strategies. As highlighted earlier, smoking has received attention recently as an independent risk factor for subsequent suicide, including in patients with psychotic illness. Bolton and Robinson (2010) calculated the Population Attributable Fraction (PAF) for a range of risk factors for suicidality, and concluded that 8% of all suicide attempts could be attributed to smoking. Smoking along with major depressive disorder, borderline personality disorder, nicotine dependence and post-traumatic stress disorder accounted for 60% of all suicidal attempts in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) database. Interestingly, our own study yielded mixed results. While univariate analysis indicated that current smokers were 1.4 times more likely (than those who never smoked) to have attempted suicide in their lifetime, adding other covariates to the logistic regression model reduced this association to non-significance. The strongest predictors for suicide attempt in our cohort were
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637
Table 3 Series of univariate logistic regressions predicting lifetime suicide attempts. OR
SE
95% CI
Female Education No secondary school qualificationa Completed secondary schooling Post-secondary school qualification
1.68nnn
0.16
(1.39–2.03)
0.73n 0.76nn
0.10 0.08
(0.55–0.97) (0.61–0.93)
Perceived loneliness Nonea Somewhat lonely Lonely Very lonely
1.49nn 1.78nnn 1.98nnn
0.21 0.23 0.30
(1.13–1.95) (1.34–2.37) (1.48–2.67)
Employment status Paid employmenta Unpaid activity or retirement No formal activity
1.64nn 1.29n
0.25 0.14
(1.22–2.20) (1.05–1.59)
Current marital status Single, never marrieda Married or defacto Separated, divorced, or widowed
1.49nn 1.73nnn
0.19 0.21
(1.16–1.93) (1.37–2.19)
Gradual or insidious illness onset Uncontrolled symptoms of mental illness Persecutory delusions (current) Substance abuse/dependence (lifetime) Alcohol abuse/dependence (lifetime) Any deliberate self-harm in past year
1.42nn 1.08nnn 1.31n 1.22 þ 1.73nnn 9.16nnn
0.15 0.02 0.14 0.13 0.16 1.64
(1.16–1.75) (1.05–1.11) (1.06–1.61) (0.99–1.50) (1.44–2.09) (6.36–12.85)
Course of illness Good recoverya Partial recovery Chronic
1.78nnn 1.68nnn
0.20 0.19
(1.42–2.23) (1.34–2.11)
Any depressive symptoms (lifetime) Any depressive symptoms (current) Comorbid physical illness (lifetime) Number of lifetime medical conditions Lack of insight (lifetime) Psychiatric inpatient admission in past year Deterioration from premorbid level of functioning Poor premorbid work adjustment Poor premorbid social adjustment Premorbid personality disorder Polypharmacy Number of psychotropic medications
3.38nnn 1.69nnn 1.54nn 1.16nnn 0.68nnn 1.30nn 1.49n 1.38nn 1.85nnn 1.84nnn 1.20 þ 1.29nnn
0.45 0.18 0.20 0.02 0.08 0.13 0.24 0.14 0.18 0.26 0.13 0.05
(2.61–4.38) (1.38–2.08) (1.19–1.99) (1.12–1.21) (0.55–0.84) (1.07–1.58) (1.08–2.05) (1.13–1.69) (1.52–2.25) (1.39–2.42) (0.97–1.49) (1.19–1.40)
ICD-10 diagnosis Schizophrenia/schizoaffectivea Bipolar (mania) Psychotic depression Other psychoses Current smoker
1.28 þ 3.03nnn 1.24 þ 1.37nn
0.16 0.78 0.17 0.14
(0.99–1.64) (1.83–5.02) (0.96–1.62) (1.12–1.66)
0.72nn 0.75n
0.09 0.10
(0.56–0.91) (0.57–0.98)
Lifetime smoking status Never smoked Former smoker Current smokera
Note: N ¼ 1797 unless otherwise stated. a
Reference category. p o 0.20. p o 0.05. nn p o 0.01. nnn p o 0.001. þ
n
self-harm in the previous 12 months, lifetime depressive symptoms, and a diagnosis of psychotic depression. Our hypotheses that the risk of suicidality would be higher in current and former smokers were not supported. We also hypothesized that the amount of daily cigarettes smoked would be associated with severity of suicidal behavior; in other words, we were looking for a dose–response relationship in severity of suicidal behaviors. However, number of cigarettes
smoked daily was not a significant predictor of lifetime suicide attempt, current suicidal ideation, or lifetime suicidal ideation respectively. Previous studies that have found a dose–response relationship between smoking and suicidal risk were conducted in the general population. Studies done in mentally ill patients that have reported such an association (e.g. Goldstein et al., 2008) also concluded that this association was reduced on regression analysis.
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Table 4 Multiple logistic regression predicting lifetime suicide attempts for current and lifetime smoking status. Current smoking status
Lifetime smoking status
OR
SE
95% CI
OR
SE
95% CI
Female
1.36n
0.17
(1.06–1.74)
1.36n
0.17
(1.06–1.73)
Education No secondary school qualificationa Completed secondary schooling Post-secondary school qualification
0.90 0.81
0.15 0.10
(0.65–1.25) (0.63–1.04)
0.90 0.81
0.15 0.10
(0.65–1.25) (0.63–1.04)
Perceived loneliness Nonea Somewhat lonely Lonely Very lonely
1.17 1.05 0.96
0.18 0.18 0.17
(0.86–1.59) (0.75–1.47) (0.67–1.36)
1.17 1.05 0.95
0.18 0.18 0.17
(0.86–1.59) (0.75–1.47) (0.67–1.36)
Employment status Paid employmenta Unpaid activity or retirement No formal activity
1.53n 1.07
0.27 0.14
(1.08–2.17) (0.83–1.39)
1.53* 1.07
0.27 0.14
(1.08–2.17) (0.83–1.39)
Current marital status Single, never marrieda Married or defacto Separated, divorced, or widowed
1.22 1.43n
0.19 0.21
(0.89–1.66) (1.08–1.90)
1.22 1.43n
0.19 0.21
(0.90–1.67) (1.08–1.90)
Gradual or insidious illness onset Uncontrolled symptoms of mental illness Persecutory delusions (current) Substance abuse/dependence (lifetime) Alcohol abuse/dependence (lifetime) Any deliberate self-harm in past year
1.24 1.03 1.15 1.03 1.68nnn 7.52nnn
0.15 0.02 0.15 0.14 0.20 1.50
(0.97–1.58) (0.99–1.06) (0.89–1.50) (0.79–1.34) (1.33–2.12) (5.09–11.10)
1.24 1.03 1.15 1.03 1.69nnn 7.51nnn
0.15 0.02 0.15 0.14 0.20 1.49
(0.97–1.58) (0.99–1.06) (0.89–1.50) (0.79–1.35) (1.33–2.14) (5.08–11.08)
Course of illness Good recoverya Partial recovery Chronic
1.38n 1.37n
0.19 0.20
(1.06–1.79) (1.02–1.84)
1.38n 1.37n
0.19 0.20
(1.06–1.79) (1.02–1.84)
Any depressive symptoms (lifetime) Any depressive symptoms (current) Comorbid physical illness (lifetime) Number of lifetime medical conditions Lack of insight (lifetime) Psychiatric inpatient admission in past year Deterioration from premorbid level of functioning Poor premorbid work adjustment Poor premorbid social adjustment Premorbid personality disorder Polypharmacy Number of psychotropic medications
2.43nnn 0.82 0.83 1.06* 0.80 0.84 0.94 1.06 1.52nn 1.08 1.02 1.19nn
0.39 0.11 0.15 0.03 0.11 0.10 0.19 0.14 0.20 0.20 0.16 0.07
(1.78–3.32) (0.63–1.07) (0.59–1.18) (1.01–1.12) (0.61–1.05) (0.66–1.06) (0.63–1.39) (0.82–1.36) (1.17–1.98) (0.75–1.56) (0.76–1.38) (1.06–1.33)
2.43nnn 0.82 0.83 1.06n 0.80 0.83 0.94 1.06 1.52nn 1.08 1.02 1.19nn
0.39 0.11 0.15 0.03 0.11 0.10 0.19 0.14 0.20 0.20 0.16 0.07
(1.78–3.32) (0.63–1.07) (0.59–1.17) (1.01–1.12) (0.61–1.05) (0.65–1.06) (0.63–1.39) (0.82–1.36) (1.17–1.98) (0.75–1.56) (0.76–1.38) (1.06–1.33)
ICD-10 diagnosis Schizophrenia/schizoaffectivea Bipolar (mania) Psychotic depression Other psychoses Current smoker
0.90 1.89n 0.96 1.27
0.15 0.56 0.16 0.16
(0.66–1.24) (1.06–3.40) (0.69–1.32) (0.99–1.63)
0.91 1.90n 0.96 –
0.15 0.57 0.16 –
(0.66–1.24) (1.06–3.40) (0.69–1.32) –
–
–
– 0.81 0.77
0.13 0.13
(0.59–1.11) (0.56–1.06)
0.11nnn
0.03
(0.06–0.20)
Lifetime smoking status Never smoked Former smoker Current smokera Constant
0.09nnn
0.03
(0.05–0.16)
Note: N ¼ 1741. a
Reference category. po 0.05. nn p o0.01. nnn p o0.001. n
Dose response relationship indicates some form of biological changes; changes that are particularly important with regards the smoking-mental illness-suicide paradigm include changes in neurochemistry (e.g. serotonin levels) (Hughes, 2008) and/or neurobiological changes (e.g., changes to orbito-frontal cortex or anterior cingulate cortex, areas implicated in increased impulsivity
and poor social-problem-solving) (Shamay-Tsoory et al., 2006; Heberlein et al., 2008). Patients with mental illness, particularly schizophrenia or schizoaffective disorders, are also associated with these changes and in fact, these may be part of the core psychopathology of the illness. It is therefore likely that any association between smoking and these changes becomes less
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evident in this group. This probably explains the absence of statistically significant findings in our group of patients and a number of previous studies that have reported similar findings. One of the major strengths of our study was that we had data on most of the known risk factors for suicide and employed it in multivariate analysis. While this study was a secondary data analysis, we had sufficient sample size to rule out type II error. As we had 299 participants with history of self-harm, with the proportion of smoking being 66.1%, and keeping the alpha as 0.05 and the relative risk at a modest 1.8 for suicidal attempts (based on a recent meta-analysis by Li et al. (2012) for completed suicide), this would give us a power of 0.89. Further, our sample comprised of Australians with a range of psychotic disorders, which provided the opportunity to study interaction effects among the different diagnostic groups; we did not find any interaction effects, suggesting that the same factors operate irrespective of diagnostic grouping. At the same time, it could be argued that there is the risk of “over-adjustment” particularly when smoking contributes to many of the risk factors adjusted for (Leistikow, 2003). The present study must be interpreted in the context of several limitations. This study was not primarily conducted to study the association between suicidal risk and smoking among patients with psychotic disorders. Hughes (2008), in his review, suggests that an ideal study investigating any association between smoking and suicidal risk should include measures of all the major risk factors for suicide and distinguish between confounders and mediators. However, such a study would be very difficult to design and/or conduct as it would require follow-up of a large cohort to study the many possible interactions between ongoing smoking, stopping smoking and taking medications. Secondly, we did not measure for any specific markers for impulsivity. Our study selection and timing of recruitment may not be representative of an acute sample, which is when the suicidal risk is highest, particularly in patients with schizophrenia (Harkavy-Friedman et al., 1999). This would, however, be less pertinent given that we wanted to study the risk cigarette smoking contributed to suicide or suicidal behaviors in patients with psychotic disorders. In order to understand how smoking might be associated with suicide, it is important to know how smoking is associated with mental illness. It has been suggested that mentally ill patients use cigarettes as a means of self-medication of psychiatric symptoms (Carmody, 1992; Addington et al., 1998). This could be interpreted as cigarette smoking having antidepressant or anxiolytic properties, such as the energizing effects of antidepressants (Teicher et al., 1993). That is, nicotine induced antidepressant effects may account for chronic insomnia and a feeling of being energized and this may precipitate suicidal attempts. An alternative view is that antecedent smoking is associated with increased risk of depression. In his review, Hughes (2008) concludes that current smoking could be associated with suicide due to third factors or confounders. This is plausible because many of the risk factors for suicide are also risk factors for being a smoker as we found in our sample. While the influence of confounders could be tested out using covariate analysis, it is also possible that the findings from previous studies may be inaccurate because the most important confounders were not included or because what was classified as confounders may be potential mediators (Breslau et al., 2005). Finally, it is likely that the same underlying factors may predispose to smoking and mental health problems (Breslau et al., 1998). 4.1. Conclusion Suicide rates among patients with schizophrenia patients remain high. Mental health professionals are often faced with what has been labeled “double trouble” (Magura, 2008), the cooccurrence of mental illness and substance use, and both factors
639
that increase the risk of suicide (Cardoso et al., 2008; Goldstein et al., 2008; Shantna et al., 2009). Secondary prevention focuses on state-dependent risk factors that can potentially be modified, including substance use (Pompili et al., 2007). While cigarette smoking has been identified as an important independent risk factor for suicide among patients with mental illness, this was not supported by our findings. It is likely that this is due to smoking being an intermediary between other more pertinent risk factors and suicide or suicidal attempts. That is, those patients who are more distressed or disabled are more likely to smoke. While smoking is associated with an increase in suicidal risk, this risk becomes less significant in those who have mental illness. This is nevertheless an important area of study. Future research should compare the suicide risk among smokers in those with and without a mental illness. There is also a need for prospective studies that focuses on the association of smoking and suicide a priori, includes as many possible confounders, and mediators and examine the effects of suicide outcomes with attempts and success of smoking cessation.
Role of funding sources This publication is based on data collected in the framework of the 2010 Australian National Survey of High Impact Psychosis. The members of the Survey of High Impact Psychosis Study Group are: V. Morgan (National Project Director), A. Jablensky (Chief Scientific Advisor), A. Waterreus (National Project Coordinator), R. Bush, V. Carr, D. Castle, M. Cohen, C. Galletly, C. Harvey, B. Hocking, A. Mackinnon, P. McGorry, J. McGrath, A. Neil, S. Saw, H. Stain. The study was funded by the Australian Government Department of Health and Ageing.
Contributors All authors contributed to the writing of this manuscript. While analysis was performed by the second author, all authors contributed to the interpretation of the results. Drafting of the manuscript was performed by the first author and contributed partly by the remaining authors.
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