Clinical Psychology and Psychotherapy Clin. Psychol. Psychother. (2015) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/cpp.1964

Comorbidity in Emetophobia (Specific Phobia of Vomiting) Mark Sykes,1,2 Mark J. Boschen1,2* and Elizabeth G. Conlon1,2 1 2

School of Applied Psychology, Griffith University, Southport, Australia Menzies Health Institute, Griffith University, Southport, Australia

Background: Emetophobia (fear of vomiting) is an anxiety disorder in which individuals report clinical levels of fear that they may vomit or be exposed to the vomit of others. The prevalence of comorbidity of emetophobia with other conditions has previously only been investigated using self-report instruments. Method: Sixty-four adults with emetophobia participated in an online structured clinical diagnostic interview assessing the presence of emetophobia and other conditions. Results: Higher comorbidity for depression, generalized anxiety disorder, panic disorder, social anxiety disorder and obsessive–compulsive disorder were found in participants compared with general population norms. Conclusions: Emetophobia is commonly comorbid with other anxiety and depressive disorders. Comorbidity rates, when assessed using a structured clinical interview, were lower than previously reported using self-report alone. Copyright © 2015 John Wiley & Sons, Ltd. Key Practitioner Message: • Emetophobia (specific phobia of vomiting) is a clinical fear of vomiting. • Individuals with emetophobia show high comorbidity with other anxiety and mood disorders. • The most common comorbid conditions were generalized anxiety disorder, panic disorder, hypochondriasis and obsessive–compulsive disorder. • Clinicians should ensure that they assess for the presence of comorbid conditions when treating emetophobia. Keywords: Anxiety Disorder, Comorbidity, Emetophobia, Fear of Vomiting, Specific Phobia

INTRODUCTION The non-clinical fear of vomiting exists in approximately 7% of women and 1.8% of men (van Hout & Bouman, 2012). When this fear intensifies into a clinically significant problem, it is referred to as emetophobia or specific phobia of vomiting (Boschen, 2007).1 Emetophobia is an anxiety disorder that affects approximately 0.1% of women and typically emerges in the early teenage years (Becker et al., 2007). While emetophobia appears to be less prevalent in men (Veale & Lambrou, 2006), specific prevalence rates for men are unknown. Despite its low prevalence rate, emetophobia still presents significant problems to those with the condition. The fear of vomiting is associated with an early onset and chronic course with few periods of remission (Lipsitz, Fyer, Paterniti, & Klein, 2001). Furthermore, the illness is *Correspondence to: Mark J. Boschen, School of Applied Psychology, Griffith University, Parklands Drive, Southport, Queensland, Australia. E-mail: m.boschen@griffith.edu.au 1 While we distinguish between non-clinical fear of vomiting and a clinical anxiety disorder, we use the terms ‘specific phobia of vomiting’ and ‘emetophobia’ synonymously, with the term emetophobia preferred throughout this manuscript.

Copyright © 2015 John Wiley & Sons, Ltd.

associated with significant distress and impairment in functioning, as well as poor response to treatment (Veale & Lambrou, 2006). Accurate diagnosis of emetophobia is sometimes difficult as the condition presents with features and symptoms that are also seen in obsessive–compulsive disorder (OCD), panic disorder, panic disorder with agoraphobia (PDA) and generalized anxiety disorder (GAD; Boschen, 2007; Veale, 2009). In addition, many individuals with a fear of vomiting also meet full diagnostic criteria for comorbid conditions such as OCD, panic disorder, panic disorder with agoraphobia, GAD and other conditions (van Hout & Bouman, 2012). In addition to conditions that have a similar presentation to emetophobia, individuals with anxiety disorders also show elevated rates of comorbidity with mood, substance and personality disorders (Brown & Barlow, 1992). It is important to identify the presence of other disorders as it is central to both classification and treatment (Brown & Barlow, 1992). For a broad base of psychiatric conditions, comorbidity has been reported to predict increased treatment costs (Goldsmith, 1999; Souêtre et al., 1994), more chronic course (Schoevers, Deeg, van Tilburg, & Beekman, 2005) and increased suicide rates (Johnson, Weissman, &

M. Sykes et al. Klerman, 1990). The issue is widespread with point prevalence comorbidity rates found to be approximately a third of the population in primary care (Roca et al., 2009) and approximately 6% in the general population (Kessler, Berglund, Demler, Jin, & Walters, 2005).

Previous Research Two previous studies have attempted to quantify the level of comorbidity in individuals with the fear of vomiting (Lipsitz et al., 2001; van Hout & Bouman, 2012). In the first study (n = 56), individuals who self-identified as having a fear of vomiting were recruited from a specialist emetophobia Internet forum group (Lipsitz et al., 2001). In the second study, the Psychiatric Screening Questionnaire was posted to randomly generated addresses in the Dutch community. From the returned surveys (n = 171), there were 15 (8.8%) who reported a fear of vomiting themselves or of seeing others vomit. In addition, a sample of 19 individuals with a self-reported fear of vomiting was obtained from an Internet emetophobia forum (van Hout & Bouman, 2012). Table 1.

The rates of comorbid diagnoses in these two previous studies indicate that as the severity of the vomiting fear increases, the rate of comorbidity increases (Table 1). Participants who self-identified as having a fear of vomiting had higher comorbidity rates for all measured conditions compared with a non-vomit-fearful community sample (van Hout & Bouman, 2012). Individuals recruited from an Internet emetophobia forum reported higher comorbidity rates than a small (n = 15) community sample that identified the same vomiting fear. With the exception of depression, the comorbidity rates reported by van Hout and Bouman are higher than the results of Lipsitz et al. (2001). The difference in comorbidity rates may be due to the different sampling and assessment methods. When compared with larger scale epidemiological research, Table 1 shows that the prevalence of comorbid conditions in emetophobia were higher than that observed in the general population (Kessler, Petukhova, Sampson, Zaslavsky, & Wittchen, 2012). For example, while social anxiety disorder was recorded as having a 12-month prevalence of 8.0% in the large Kessler et al. (2012) community epidemiological study, it occurred in 19.5% and 63.2% of individuals in a community vomit-fearful and Internet

Axis-I disorders in the community and vomit-fearful populations Lipsitz et al. (2001)

van Hout and Bouman (2012)

Kessler et al. (2012)

Current study

Sample source

Internet emetophobic

Community controls

Community epidemiological

Internet emetophobic

Sample size (n) Diagnostic method

56 Selfreported diagnosis Lifetime prevalence

156

5223 NCS-R interview

64 SCID

12 months

Point prevalence

30% 40%†

— 7.1% 5.8% 12.2% 2.6% — — — 5.8% — 2.6% — — —

10.1% 3.1%† 1.7%‡ 8.0% 1.3% 2.9% 4.4% — — 1.5% 9.3% 2.6% 1.7% —

— 12.5%†

Prevalence Diagnosis Specific phobia Panic disorder Agoraphobia SocAD OCD GAD PTSD AD-NOS Hypochondriasis Dysthymia Depression Bipolar BDD SomatDis

21% 18% — — — — — 46% — — —

Internet Community vomitvomitfearful fearful 15 19 Psychiatric Diagnostic Screening Questionnaire Point prevalence — 20.0% 20.0% 19.5% 26.7% — — — 7.9% — 13.3% — — —

— 52.6% 84.2% 63.2% 31.6% — — — 26.3% — 21.1% — — —

7.8% 12.5% 28.1% 1.6% 9.4% 12.5% 3.1% 7.8% 0.0% 1.6% 7.8%

Odds ratio

4.5 1.0 10.8 13.1 0.4 2.1 0.8 0.0 0.9



Includes individuals with panic disorder and/or agoraphobia. Includes individuals with or without a history of panic disorder. AD-NOS = anxiety disorder not otherwise specified. BDD = body dysmorphic disorder. Bipolar = bipolar mood disorder. Dysthymia = dysthymic disorder. NCS-R = National Comorbidity Survey Replication. OCD = obsessive–compulsive disorder. PTSD = post-traumatic stress disorder. SCID = structured clinical interview for Diagnostic and Statistical Manual of Mental Disorders-IV. SocAD = social anxiety disorder. SomatDis = somatoform disorder. GAD = generalized anxiety disorder. ‡

Copyright © 2015 John Wiley & Sons, Ltd.

Clin. Psychol. Psychother. (2015)

Emetophobia Comorbidity vomit-fearful groups, respectively (van Hout & Bouman, 2012). Depressive disorder, present in 9.3% of individuals in the Kessler et al. (2012) community epidemiological study, was observed in 13.3% to 21.1% of vomit-fearful participants by van Hout and Bouman (2012). In the clinical population, the estimates rise to almost an eightfold increase for social anxiety disorder and a doubling for depression. As the fear of vomiting becomes more severe, the degree of comorbidity rises substantially. Three limitations of the previous research were assessment tool validity, sample size and participant bias. Van Hout and Bouman’s comorbidity rates were based on an unpublished Dutch translation of the Psychiatric Diagnostic Screening Questionnaire (Arrindell, 2004). This is a self-report questionnaire used to assess for the presence of common Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV Axis I disorders. The van Hout and Bouman assessment tool validity can be cross checked by comparing their control community incidence with the Kessler et al. epidemiological sample of 5223 individuals, as the two should be similar. Table 1 shows that the comparison indicates that with the exception of depression, the comorbidity rates reported by van Hout and Bouman are substantially higher than would be expected, indicating either that the Dutch version of the Psychiatric Diagnostic Screening Questionnaire has validity issues or that the American and Dutch anxiety and depression rates are dissimilar. The assessment tool used by Lipsitz et al. was based on an unpublished 29-item self-reported questionnaire that has an unknown diagnostic validity. In both studies, the validity of the comorbidity rates is uncertain. Both emetophobia studies had relatively small sample sizes (19–56), and therefore, small variations in the sample could disproportionally influence comorbidity rates. In addition, the selection of the participants from a specialist Internet support group may attract individuals whose condition is more severe than those individuals with a vomit phobia that have not sought external support. The current study quantifies the point prevalence comorbidity rates for individuals with a self-reported fear of vomiting using a structured clinical assessment, rather than self-report questionnaires. We tested the specific hypothesis that rates of mental disorders will be higher in a cohort of individuals with emetophobia than in the general population.

Participants A total of 64 adults (55 females and 9 males), aged 19–63 years (M = 32.2, standard deviation = 8.1) participated. A total of 40 (63%) were living in USA, 7 (11%) in Australia, 10 (16%) in the UK, 4 (6%) in Canada, with the remaining 3 (5%) in Ireland, Romania and New Zealand. The participants identified as 42 (56.6%) employed, 10 (15.6%) homemakers, 9 (14.1%) students, 2 (3.1%) on sick leave and 1 (1.6%) unemployed.

Measures The DSM-IV Axis I diagnosis was conducted using a point prevalence structured clinical interview. The structured clinical interview for DSM-IV Axis I disorders (SCID-I; Spitzer, Williams, Gibbon, & First, 1992) was administered via Skype and scored online using NetSCID (TeleSage, 2011). The SCID-I has been found to have moderate to excellent inter-rater agreement of Axis I disorders (Lobbestael, Leurgans, & Arntz, 2011). Each assessment took approximately 90 to 120 min to administer.

Procedure Participants were recruited using advertisements posted to an international emetophobia forum community and from the wider public using paid web-based advertising in exchange for a free online emetophobia treatment programme. The participants self-identified as having a fear of vomiting and at the commencement of treatment were asked to complete an optional telephone/videoconference structured clinical assessment as part of the induction phase. Of a total of 513 participants who signed into the web page and were invited to complete the interview, 64 participants agreed to a structured clinical interview and completed an online consent form. There were no stated inclusion or exclusion criteria for the treatment except a minimum age of 18 years. The interview was conducted by one of the authors (MS), an Australian registered psychologist, and was guided and coded using the online NetSCID application.

RESULTS METHOD Statement of Ethical Consideration This research was approved by the Human Research Ethics Committee of Griffith University, and it conforms to the provisions of the Declaration of Helsinki, as revised in Edinburgh in 2000. Consent was provided by all participants both verbally and through the use of an online consent form. Copyright © 2015 John Wiley & Sons, Ltd.

All 64 participants had a DSM-IV-TR diagnosis of emetophobia (specific phobia of vomiting) confirmed using the SCID. Point prevalence rates for Axis-I disorders based on structured clinical interviews are shown in Table 1. A total of 26 (41%) of participants showed no evidence of comorbidity. Compared with a community sample (Kessler et al., 2012), the sample of individuals with clinically diagnosed emetophobia was 4.5 times more Clin. Psychol. Psychother. (2015)

M. Sykes et al. likely to be diagnosed with panic disorder, 10.8 times more likely to be diagnosed with OCD, 13.1 times more likely to be diagnosed with GAD and 2.1 times more likely to be diagnosed with dysthymia. Social anxiety disorder, posttraumatic stress disorder (PTSD), major depressive disorder, bipolar and body dysmorphic disorder rates were lower than those found in the epidemiological sample. The percentage of individuals in the clinic diagnosed sample with panic disorder, social anxiety disorder, OCD and depression (in total) were all lower when compared with the studies of both Lipsitz et al. (2001) and van Hout and Bouman (2012). The level of hypochondriasis was about half of that reported by van Hout and Bouman in their Internet vomit-fearful group (Table 1).

DISCUSSION The results in general support the hypothesis that individuals with emetophobia have higher comorbidity rates than would be expected in the general population. The odds ratio shown in Table 1 highlight that PTSD, bipolar disorder and body dysmorphic disorder are lower than would be expected compared with the Kessler epidemiological sample. This could reflect self-selection for a treatment programme, random variation due to the small SCID sample size (n = 64), and lower levels of point prevalence diagnosis compared with a 12-month period. The results show that previous self-reported comorbidity rates are substantially higher than the clinician assessed rates, indicating that self-report measures when used alone could overdiagnose clinical symptoms of fear of vomiting and other comorbid disorders. Lower comorbidity rates may also be an artefact of low emetophobia base rates or differences between (potentially non-clinical) vomit-fearful individuals and those with clinical emetophobia. In addition, some of the emetophobia symptoms closely overlap between DSM-IV conditions, and the previous studies’ self-assessment measures appear to be more additive than discriminatory compared with a structured clinical interview. The strength of the current study is that 64 individuals reporting symptoms of emetophobia all underwent a structured clinical diagnostic interview to confirm the presence of the condition. Although our sample size was similar to one previous study, the diagnoses used previously were obtained only from self-report. The results presented in the current study were obtained using a structured clinical interview, which gives greater certainty to the accuracy of the obtained emetophobia diagnosis, and the diagnosis of comorbid conditions. Additionally, the recruitment of subjects predominately from an Internet forum group can introduce systematic bias into the sample. Copyright © 2015 John Wiley & Sons, Ltd.

The relative rarity of emetophobia makes it difficult to access a broad cross section of affected individuals. Future research should significantly increase sample size and seek a representative sample by drawing participants from a wider clinical sample than the Internet. Future emetophobia treatment studies could investigate the impact comorbidity has on initial severity, quality of life and treatment outcome. The community sample recruitment methodology used by van Hout and Bouman is an example of a potentially suitable research strategy. We believe that our results carry several important implications for the understanding of emetophobia. First, 41% (26) of participants showed no other comorbidities, and this indicates that the diagnosis of emetophobia is more than a set of overlapping symptoms but a distinct condition in its own right. Second, our results indicate that people with emetophobia have high levels of comorbid conditions such as panic disorder, social anxiety disorder, OCD, depression and hypochondriasis. Finally, individuals with emetophobia may be significantly more likely to experience other psychiatric conditions than people in the general population. Our results suggest that clinicians should routinely investigate the presence of additional comorbid DSM-IV Axis I disorders when a diagnosis of emetophobia is present. The long-term outcomes for individuals with emetophobia and comorbid conditions have not been reported, but the early identification of individuals with a complex presentation may help prioritize treatment plans (Boschen & Oei, 2008) and assist in reducing the likely risks of increased treatment costs and chronicity. In summary, this study indicates that individuals with emetophobia have comorbidity rates for psychiatric disorders that are higher than the general population but lower than previously reported.

REFERENCES Arrindell, W. A. (2004). Dutch translation of the psychiatric diagnostic screening questionnaire (PDSQ). Groningen: Department of Clinical and Developmental Psychology, University of Groningen. Becker, E. S., Rinck, M., Türke, V., Kause, P., Goodwin, R., Neumer, S., & Margraf, J. (2007). Epidemiology of specific phobia subtypes: Findings from the Dresden mental health study. European Psychiatry, 22, 69–74. Boschen, M. J. (2007). Reconceptualizing emetophobia: A cognitive-behavioral formulation and research agenda. Journal of Anxiety Disorders, 21, 407–419. Boschen, M. J., & Oei, T. P. S. (2008). A cognitive behavioral case formulation framework for treatment planning in anxiety disorders. Depression and Anxiety, 25, 811–823. Brown, T. A., & Barlow, D. H. (1992). Comorbidity among anxiety disorders: Implications for treatment and DSM-IV. Journal of Consulting and Clinical Psychology, 60, 835–844. Goldsmith, R. J. (1999). Overview of psychiatric comorbidity. Psychiatric Clinics of North America, 22, 331–349.

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Emetophobia Comorbidity Johnson, J., Weissman, M. M., & Klerman, G. L. (1990). Panic disorder, comorbidity, and suicide attempts. Archives of General Psychiatry, 47, 805–808. Kessler, R. C., Berglund, P., Demler, O., Jin, R., & Walters, E. E. (2005). Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the national comorbidity survey replication. Archives of General Psychiatry, 62, 593–602. Kessler, R. C., Petukhova, M., Sampson, N. A., Zaslavsky, A. M., & Wittchen, H. (2012). Twelve-month and lifetime prevalence and lifetime morbid risk of anxiety and mood disorders in the United States. International Journal of Methods in Psychiatric Research, 21, 169–184. Lipsitz, J. D., Fyer, A. J., Paterniti, A., & Klein, D. F. (2001). Emetophobia: Preliminary results of an Internet survey. Depression and Anxiety, 14, 149–152. Lobbestael, J., Leurgans, M., & Arntz, A. (2011). Inter-rater reliability of the structured clinical interview for DSM-IV axis I disorders (SCID I) and axis II disorders (SCID II). Clinical Psychology and Psychotherapy, 18, 75–79. Roca, M., Gili, M., Garcia-Garcia, M., Salva, J., Vives, M., Garcia Campayo, J., & Comas, A. (2009). Prevalence and comorbidity

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of common mental disorders in primary care. Journal of Affective Disorders, 119, 52–58. Schoevers, R. A., Deeg, D. J. H., van Tilburg, W., & Beekman, A. T. F. (2005). Depression and generalized anxiety disorder: Co-occurrence and longitudinal patterns in elderly patients. American Journal of Geriatric Psychiatry, 13, 31–39. Souêtre, E., Lozet, H., Cimarosti, I., Martin, P., Chignon, J. M., Adès, J., et al. (1994). Cost of anxiety disorders: Impact of comorbidity. Journal of Psychosomatic Research, 38, 151–160. Spitzer, R. L., Williams, J. B. W., Gibbon, M., & First, M. B. (1992). The structured clinical interview for DSM-III-R (SCID) I: History, rationale, and description. Archives of General Psychiatry, 49, 624–629. TeleSage. (2011). NetSCID, 2011, (Available from http://web. telesage.com/products/netscid.php) van Hout, W. J., & Bouman, T. K. (2012). Clinical features, prevalence and psychiatric complaints in subjects with fear of vomiting. Clinical Psychology and Psychotherapy, 19, 531–539. Veale, D. (2009). Cognitive behaviour therapy for a specific phobia of vomiting. Cognitive Behaviour Therapy, 2, 272–288. Veale, D., & Lambrou, C. (2006). The psychopathology of vomit phobia. Behavioural and Cognitive Psychotherapy, 34, 139–150.

Clin. Psychol. Psychother. (2015)

Comorbidity in Emetophobia (Specific Phobia of Vomiting).

Emetophobia (fear of vomiting) is an anxiety disorder in which individuals report clinical levels of fear that they may vomit or be exposed to the vom...
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