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ScienceDirect Comprehensive Psychiatry 59 (2015) 123 – 128 www.elsevier.com/locate/comppsych
Validation of the Korean version of the Connor–Davidson Resilience Scale-2 in firefighters and rescue workers Hyeonseok S. Jeong a , Ilhyang Kang b, c, 1 , Eun Namgung b, c, 1 , Jooyeon Jamie Im b, d , Yujin Jeon b, e , Jihee Son b, e , Siyoung Yu b, c , Sungeun Kim b, c , Sujung Yoon b , In Kyoon Lyoo b, e , Yong-An Chung f , Jae-ho Lim g , Jieun E. Kim b, c,⁎ a
Department of Radiology, Incheon St. Mary's Hospital, The Catholic University of Korea, Seoul, South Korea b Ewha Brain Institute, Ewha W. University, Seoul, South Korea c Department of Brain and Cognitive Sciences, Ewha W. University, Seoul, South Korea d Interdisciplinary Program in Neuroscience, College of Natural Sciences, Seoul National University, Seoul, South Korea e Graduate School of Pharmaceutical Sciences, Ewha W. University, Seoul, South Korea f Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul, South Korea g Central Officials Training Institute, Gwacheon, Gyeonggi-do, South Korea
Abstract Objective: Resilience has been considered as a protective factor against stress. Evaluating resilience in firefighters and rescue workers, who are frequently exposed to traumatic events, is important and relevant. This study examined the psychometric properties of the Korean version of the Connor–Davidson Resilience Scale-2 (CD-RISC2). Methods: Two-hundred twenty-two current professional firefighters and rescue workers were assessed by standardized, semi-structured clinical interviews and self-report questionnaires. Internal consistency, correlation with the CD-RISC, convergent validity, divergent validity, and predictive validity of posttraumatic stress disorder (PTSD) symptom severity were analyzed. Results: The CD-RISC2 demonstrated good internal consistency (α = 0.75), item-total correlation (r = 0.89–0.90), and convergent and divergent validity. The total score of the CD-RISC2 showed significant correlations with the subtotal of the remaining 23 CD-RISC items (r = 0.77, p b 0.001) and with the score of each CD-RISC item (r = 0.15–0.66, all p b 0.05). The magnitude of the relationship between the number of traumatic experiences and PTSD symptom severity was greater in the low resilience group than in the high resilience group (p for interaction = 0.002). The likelihood-ratio test confirmed that the model predicting PTSD symptom severity based on the CD-RISC2 total score was not improved by the inclusion of subtotal scores of the remaining 23 CD-RISC items (χ 2 = 0.31, p = 0.58). Conclusions: These results suggest that the CD-RISC2 would be a valuable tool in evaluating resilience quickly and efficiently in firefighters and rescue workers. © 2015 Elsevier Inc. All rights reserved.
1. Introduction
Financial support: This study was supported by the grant from the National Emergency Management Agency of Korea and the Medi-Star Program from the Korean Ministry of Health and Welfare (A112009). Disclosure: The authors declare that there are no financial conflicts of interest. ⁎ Corresponding author at: Room # 202, Posco-Building, Department of Brain and Cognitive Sciences, Ewha W. University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, South Korea. Tel.: +82 2 3277 6930; fax: +82 2 3277 6932. E-mail address: [email protected] (J.E. Kim). 1 These authors contributed equally to this work. http://dx.doi.org/10.1016/j.comppsych.2015.01.006 0010-440X/© 2015 Elsevier Inc. All rights reserved.
Resilience has been defined as a successful stress-coping ability that adaptively maintains physiological and psychological stability in the face of adversity [1]. It has been reported that resilience plays an influential role in buffering the adverse effects of traumatic events and protecting against the development of post-traumatic stress disorder (PTSD) or major depressive disorder (MDD) [1–4]. While people with high resilience recover quickly from psychological distress caused by trauma experiences, people with low resilience could not appropriately respond to post-traumatic stress [2]. A body of literature has shown that the degree of
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resilience, if measured accurately, can predict the development and treatment outcome of PTSD or MDD following trauma exposure [4,5]. Therefore, it is necessary to distinguish people with low resilience, who are vulnerable to mental illness after trauma exposure [1]. Firefighters and rescue workers are more frequently exposed to traumatic events than the general population due to the nature of their work [6]. Not surprisingly, high prevalence rates of PTSD and MDD in firefighters and rescue workers have consistently been reported. For instance, the point prevalence rates of probable PTSD and MDD in rescue workers exposed to the 9/11 World Trade Center disaster were 16.7% and 21.7%, respectively [7], whereas the lifetime prevalence rates of PTSD and MDD in the US general population were 7.8% and 16.2% [8,9]. The issue of mental health in firefighters and rescue workers is of critical importance because such concerns are not limited to affected individuals but are extended to public safety and welfare. Considering the protective role of resilience against PTSD or MDD symptoms [1,4], measuring resilience level in this occupation group would be important and helpful in identifying high-risk individuals for PTSD or MDD and providing them with early preventive interventions [5,6,10]. The Connor–Davidson Resilience Scale (CD-RISC), a widely used measure to quantify the level of self-perceived resilience [11], has shown its ability to identify target groups for interventions to prevent PTSD development [5]. The CD-RISC2, a shortened version of the CD-RISC, has an additional advantage of considerably decreased time to administer and measure the level of resilience with similar efficiency [12]. While the CD-RISC is composed of 25 items, the CD-RISC2 has only two items assessing whether the respondents are “able to adapt to change” and “tend to bound back after illness or hardships.” Among the general population and psychiatric patients including PTSD or MDD in the US, the CD-RISC2 demonstrated good test-retest reliability, convergent validity, divergent validity, and showed significant correlations with both the overall score and each item score of the CD-RISC, suggesting that the CD-RISC2 is a good representative of the CD-RISC [12]. The CD-RISC has shown good reliability and validity across various cultures including South Korea [13] and China [14], and has been applied to diverse populations, such as to war veterans [15] and to cancer patients [16]. However, the CD-RISC2 has not yet been validated in Asia or among firefighters and rescue workers. The purpose of the current study was to evaluate the psychometric properties of the Korean version of the CD-RISC2 in firefighters and rescue workers using semi-structured clinical interviews and self-report questionnaires. Our analyses included internal consistency, convergent validity, divergent validity, correlation with the CD-RISC, and predictive validity of PTSD symptom severity.
2. Methods 2.1. Participants Current firefighters and rescue workers were recruited from four fire stations in Seoul, South Korea. Participants were notified of guaranteed anonymity of personal information, and freedom to withdraw from the study at any point. Participants provided written informed consent before participating in the study. Ewha W. University Bioethics Committee reviewed and approved the study protocol. 2.2. Semi-structured interviews Semi-structured interviews were conducted by research clinicians who were trained by a board-certified psychiatrist (Y.J.). The interviews were conducted face-to-face in a private room in each of the fire stations where the participants work. Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV-Text Revision (DSM-IV-TR) was performed to diagnose PTSD or MDD [17]. The Hamilton Depression Rating Scale (HDRS) [18] and the Montgomery-Åsberg Depression Rating Scale (MADRS) [19] were used to assess depressive symptoms, and Hamilton Anxiety Rating Scale (HARS) to measure anxiety symptoms [20]. The Clinician-Administered PTSD Scale (CAPS) was used to measure PTSD symptom severity [21], and the Global Assessment of Functioning (GAF) Scale, which is included in DSM-IV-TR [22], to evaluate the overall psychological and socio-occupational functioning levels of the participants. The socioeconomic status, in addition, was evaluated using the Hollingshead Four-Factor Index of Socioeconomic Status [23]. 2.3. Self-report questionnaires The CD-RISC, a 25-item self-administered questionnaire, and the CD-RISC2, which is composed of items 1 and 8 from the CD-RISC, were used to assess resilience [11,12]. The total scores of the CD-RISC and the CD-RISC2 range from 0 to 100 and from 0 to 8, respectively. Higher total score in the CD-RISC or CD-RISC2 indicates greater resilience. The Beck Depression Inventory-II (BDI-II) [24] and the Beck Anxiety Inventory (BAI) [25] were used to measure depressive and anxiety symptom severity, respectively. To evaluate PTSD symptoms, the Impact of the Event Scale-Revised (IES-R) [26] and the Post-traumatic Stress Diagnostic Scale (PDS) [27] were used. The Life Event Checklist (LEC) was used to test whether the respondents have experienced 16 types of traumatic events in their lifetime [21]. To measure physical and mental functioning levels, the Short-Form 36-item Health Survey (SF-36) was used [28]. Alcohol use problems were evaluated using the Alcohol Use Disorder Identification Test (AUDIT) [29]. 2.4. Statistical analysis Independent t-test was used to compare the CD-RISC2 total scores between men and women. One-way analysis of
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variance (ANOVA) with post-hoc Scheffe's tests was performed to compare the CD-RISC2 total scores among the PTSD with MDD group, PTSD or MDD group, and the control group. Linear trend tests using logistic regression were used to evaluate the general trend in the CD-RISC2 total scores across the diagnostic groups. The relationship between the CD-RISC2 total score and participants' age and socioeconomic status was tested using linear regression. Internal consistency was evaluated using Cronbach's alpha. Item-total correlation was assessed by Pearson's correlation. The correlations between the CD-RISC2 total score and the subtotal scores of the remaining 23 CD-RISC items and between the CD-RISC2 total score and each CD-RISC item score were analyzed. Because resilience has been reported to be associated with depression, anxiety, and PTSD [1], convergent validity of the CD-RISC2 was evaluated by calculating Pearson's correlations between the CD-RISC2 total score and the scores of the HDRS, MADRS, HARS, CAPS, GAF, BDI-II, BAI, IES-R, PDS, and SF-36. Based on the report that the CD-RISC score was not associated with measures of alcohol use and problems, divergent validity was tested by correlating the total score of the CD-RISC2 and AUDIT [30]. Linear regression analysis assessed whether individuals with lower resilience level showed stronger relationship between the number of traumatic experiences reported in the LEC and PTSD symptoms. Participants with CD-RISC2 scores greater than or equal to the group mean score were categorized as high resilience group, while participants with CD-RISC2 scores less than the group mean score were categorized as low resilience group. Independent t-test was used to compare the current CAPS total scores between the low resilience group and the high resilience group. The regression analysis was conducted with the current CAPS total score as the dependent variable, and the number of traumatic experiences, the type of resilience groups, and their interaction term as the independent variables. Likelihood-ratio test was used to determine whether a model predicting the current CAPS total score based on the CD-RISC2 total score was not improved by the inclusion of subtotal scores from the remaining 23 CD-RISC items. All analyses were conducted using the STATA version 12.1 (StataCorp., College Station, TX). All statistical analyses were two-tailed with an alpha level of 0.05.
3. Results A total of 222 firefighters and rescue workers participated in the study (201 men and 21 women). The mean age was 40.2 ± 9.2 years. The average length of the service as a firefighter or a rescue worker was 12.7 ± 8.8 years. The numbers of participants who were diagnosed as PTSD with MDD and PTSD or MDD were 7 and 21, respectively. The mean CD-RISC2 score of the entire participants was 5.9 ± 1.3. The one-way ANOVA showed significant difference in
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terms of the mean CD-RISC2 scores across the diagnostic groups (F = 6.96, p b 0.001). Results from the post-hoc test are demonstrated in Table 1. The CD-RISC2 total score decreased from 6.0 in the control group to 5.1 in the PTSD or MDD group, and 4.4 in the PTSD with MDD group (p for linear trend b 0.001). The mean scores of men and women were 5.9 ± 1.3 and 5.8 ± 0.8 respectively, showing no significant difference between the groups (p = 0.79). The CD-RISC2 score was not associated with age (p = 0.31), but was positively associated with socioeconomic status of the participants (β = 0.19, R 2 = 0.02, p = 0.03). Cronbach's alpha of the CD-RISC2 was 0.75. Questions 1 (r = 0.89, p b 0.001) and 2 (r = 0.90, p b 0.001) were positively correlated with the total score of the CD-RISC2. The total score of the CD-RISC2 showed significant correlation with the subtotal of the remaining 23 CD-RISC items (r = 0.77, p b 0.001) and the score of each CD-RISC item (r = 0.15–0.66, all p b 0.05) (Table 2). Results from the tests to confirm convergent and divergent validity are summarized in Table 3. The mean CD-RISC2 score of the low resilience group (n = 71) was 4.4 ± 0.9 and that of the high resilience group (n = 151) was 6.5 ± 0.8. The difference in the current CAPS scores between the low resilience group (5.0 ± 11.1, n = 69) and the high resilience group (3.1 ± 6.5, n = 146) was not significant (p = 0.11). The magnitude of relationship between the number of traumatic experiences and the current CAPS scores was greater in the low resilience group than the high resilience group (t = −3.17, p for interaction = 0.002) (Fig. 1), indicating that PTSD symptom scores increased more steeply in the low resilience group compared to the high resilience group as the number of traumatic experiences increased. The likelihood-ratio test confirmed that the model predicting the current CAPS total score based on the CD-RISC2 total score was not improved by the inclusion of subtotal scores from the remaining 23 CD-RISC items (χ 2 = 0.31, p = 0.58).
4. Discussion To the best of our knowledge, the current study is the first to examine psychometric properties of the CD-RISC2 in Korean firefighters and rescue workers. The CD-RISC2 Table 1 The total score of the Connor–Davidson Resilience Scale-2 for each diagnostic group. a
CD-RISC2 score
PTSD with MDD group
PTSD or MDD group
Control group
4.4 ± 1.5 b
5.1 ± 1.5 b
6.0 ± 1.2
CD-RISC2 = Connor-Davidson Resilience Scale-2; MDD = major depressive disorder; PTSD = posttraumatic stress disorder. a The diagnosis was based on the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV-Text Revision. b p b 0.05 compared with the control group.
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Table 2 Correlations between the total score of the Connor-Davidson Resilience Scale-2 a and each item of the Connor-Davidson Resilience Scale. b CD-RISC item number 2 3 4 5 6 7 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
r
p
0.58 0.15 0.65 0.64 0.55 0.55 0.48 0.55 0.66 0.52 0.57 0.49 0.51 0.65 0.65 0.45 0.58 0.18 0.52 0.61 0.48 0.61 0.54
b0.001 0.03 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 0.01 b0.001 b0.001 b0.001 b0.001 b0.001
CD-RISC = Connor-Davidson Resilience Scale. a The CD-RISC2 was composed of items 1 and 8 from the CD-RISC. b n = 221.
Table 3 Convergent and divergent validity of the Connor-Davidson Resilience Scale-2. Measure Convergent validity BAI a BDI-II b HDRS c HARS c MADRS c CAPS c PDS b IES-R d SF-36 mental component summary e SF-36 physical component summary e GAF f Divergent validity AUDIT a
r
p
−0.37 −0.45 −0.41 −0.39 −0.41 −0.15 −0.41 −0.35 0.47 0.36 0.33
b0.001 b0.001 b0.001 b0.001 b0.001 0.03 b0.001 b0.001 b0.001 b0.001 b0.001
−0.09
0.17
BAI = Beck Anxiety Inventory; BDI-II = Beck Depression Inventory-II; HDRS = Hamilton Depression Rating Scale; HARS = Hamilton Anxiety Rating Scale; MADRS = Montgomery-Åsberg Depression Rating Scale; CAPS = Clinician-Administered Posttraumatic Stress Disorder Scale; PDS = Post-Traumatic Stress Diagnostic Scale; IES-R = Impact of Event Scale-Revised; SF-36 = Short-Form 36-Item Health Survey; GAF = Global Assessment of Functioning; AUDIT = Alcohol Use Disorder Identification Test. a n = 221. b n = 222. c n = 215. d n = 220. e n = 219. f n = 207.
demonstrated satisfactory reliability and validity among firefighters and rescue workers. In addition, the explanatory power of the CD-RISC2 in predicting the current PTSD symptom severity was equivalent to that of the CD-RISC. The mean CD-RISC2 score of the entire sample (mean = 5.9) is lower than that of the US general population (mean = 6.9), but is similar to that of the family medicine outpatients in the US (mean = 6.0) [12]. This difference may have stemmed from the cultural differences, which are frequently observed for other psychometric assessment tools. For example, in responses to a Likert scale, East Asians chose the midpoint more often on items that involved expressing positive emotion than did Americans, who were more likely to demonstrate a positive emotion [31]. In addition, firefighters and rescue workers have frequently been exposed to extremely traumatic events, which may result in the decrease of the resilience level [32]. A significant decreasing trend is seen in the mean CD-RISC2 score from the control group to the PTSD or MDD group, and to the PTSD with MDD group, as shown in the previous report [12]. In terms of demographic characteristics, neither age nor sex had a significant correlation with the CD-RISC2 total score. These results are consistent with previous literatures [11,12]. Socioeconomic status was positively correlated with resilience. This result is supported by previous studies showing a positive association between resilience and education level, which is one of the most widely used measure of socioeconomic status in epidemiological studies [33,34]. Considering the fact that the CD-RISC2 consists of only two items, Cronbach's alpha of 0.75 was acceptable. The CD-RISC2 total score was significantly correlated with the subtotal of the remaining CD-RISC items and with each CD-RISC item score, suggesting that the CD-RISC2 is a reliable alternative measure of the CD-RISC. As we hypothesized, the CD-RISC2 demonstrated good convergent validity with the CD-RISC and other measures evaluating depression (HDRS, MADRS, BDI-II), anxiety (HARS, BAI), PTSD symptoms (CAPS, PDS, IES-R), overall health (SF-36), and overall functioning level (GAF). No association between the CD-RISC2 and the AUDIT provided evidence for the divergent validity, as we have expected. The likelihood-ratio test showed that the CD-RISC2 was as reliable as the CD-RISC in predicting PTSD symptom severity. Additionally, the CD-RISC2 successfully distinguished PTSD-vulnerable individuals by identifying low resilience group from high resilience group. These results suggest that the CD-RISC2, which is much shorter than the CD-RISC, may effectively substitute for the CD-RISC in firefighters and rescue workers. Although the results of the current study are promising, some limitations should be addressed. First, the participants were recruited only in Seoul, the capital city of South Korea, but firefighters and rescue workers in rural area may have different characteristics than those in metropolitan area. Second, test–retest reliability was not measured. Further study would be warranted to assess both short-term and
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Fig. 1. The relationship between the number of traumatic experiences and the severity of PTSD symptoms according to the resilience groups.Solid line shows the predicted CAPS total score by the LEC total score in the low resilience group, while dashed line is for the high resilience group. Participants with greater-than-mean CD-RISC2 total score and those with smaller were grouped as high and low resilience group, respectively.PTSD = post-traumatic stress disorder; CAPS = Clinician-Administered PTSD Scale; LEC = Life Events Checklist.
long-term test–retest reliabilities. Third, potential biomarkers of resilience such as neuropeptide Y were not used to validate the CD-RISC2 [35]. However, one of our strengths is that all subjects were thoroughly assessed by standardized, semi-structured clinical interviews as well as well-validated self-report measures. Resilience is not a fixed trait from birth. Instead, it can be conceptualized as a dynamic process that changes over time depending on the interactions between genetic variations and the environment [36]. Therefore, for effective prevention of PTSD and other mental disorders caused by frequent trauma exposure in firefighters and rescue workers, it would be highly important to monitor their levels of resilience on a regular basis. In an effort to prevent stress-induced mental disorders, resilience training programs could be developed and applied to firefighters and rescue workers. These programs have been proved to be efficacious in reducing stress and increasing the level of resilience among various groups with high occupational stress, such as in police officers and in military soldiers [37,38]. The CD-RISC2 was reliable and valid in measuring the level of resilience in the current study. Furthermore, the CD-RISC2 is not only very short but also as efficient as the CD-RISC. Therefore, the CD-RISC2 would be a valuable tool in evaluating resilience quickly and efficiently to protect mental health of firefighters and rescue workers. References [1] Agaibi CE, Wilson JP. Trauma, PTSD, and resilience: a review of the literature. Trauma Violence Abuse 2005;6:195-216. [2] Bonanno GA. Loss, trauma, and human resilience: have we underestimated the human capacity to thrive after extremely aversive events? Am Psychol 2004;59:20-8. [3] Bonanno GA, Galea S, Bucciarelli A, Vlahov D. What predicts psychological resilience after disaster? The role of demographics, resources, and life stress. J Consult Clin Psychol 2007;75:671-82.
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[29] Saunders JB, Aasland OG, Babor TF, de la Fuente JR, Grant M. Development of the Alcohol Use Disorders Identification Test (AUDIT): WHO collaborative project on early detection of persons with harmful alcohol consumption-II. Addiction 1993;88:791-804. [30] Goldstein AL, Faulkner B, Wekerle C. The relationship among internal resilience, smoking, alcohol use, and depression symptoms in emerging adults transitioning out of child welfare. Child Abuse Negl 2013;37:22-32. [31] Lee JW, Jones PS, Mineyama Y, Zhang XE. Cultural differences in responses to a Likert scale. Res Nurs Health 2002;25:295-306. [32] Knowles A. Resilience among Japanese atomic bomb survivors. Int Nurs Rev 2011;58:54-60. [33] Rabkin JG, Remien R, Katoff L, Williams JB. Resilience in adversity among long-term survivors of AIDS. Hosp Community Psychiatry 1993;44:162-7. [34] Morgenstern M. Socioeconomic factors: concepts, measurement and health effects. Galveston, TX: NHLBI Workshop on “Measuring Psychosocial Variables in Epidemiological Studies of Cardiovascular Disease.”; 1983. [35] Morgan III CA, Wang S, Southwick SM, Rasmusson A, Hazlett G, Hauger RL, et al. Plasma neuropeptide-Y concentrations in humans exposed to military survival training. Biol Psychiatry 2000;47:902-9. [36] Kim-Cohen J, Turkewitz R. Resilience and measured gene-environment interactions. Dev Psychopathol 2012;24:1297-306. [37] Casey Jr GW. Comprehensive soldier fitness: a vision for psychological resilience in the US Army. Am Psychol 2011;66:1-3. [38] Weltman G, Lamon J, Freedy E, Chartrand D. Police department personnel stress resilience training: an institutional case study. Glob Adv Health Med 2014;3:72-9.
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Validation of the Korean version of the Connor–Davidson Resilience Scale-2 in firefighters and rescue workers Hyeonseok S. Jeong a , Ilhyang Kang b, c, 1 , Eun Namgung b, c, 1 , Jooyeon Jamie Im b, d , Yujin Jeon b, e , Jihee Son b, e , Siyoung Yu b, c , Sungeun Kim b, c , Sujung Yoon b , In Kyoon Lyoo b, e , Yong-An Chung f , Jae-ho Lim g , Jieun E. Kim b, c,⁎ a
Department of Radiology, Incheon St. Mary's Hospital, The Catholic University of Korea, Seoul, South Korea b Ewha Brain Institute, Ewha W. University, Seoul, South Korea c Department of Brain and Cognitive Sciences, Ewha W. University, Seoul, South Korea d Interdisciplinary Program in Neuroscience, College of Natural Sciences, Seoul National University, Seoul, South Korea e Graduate School of Pharmaceutical Sciences, Ewha W. University, Seoul, South Korea f Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul, South Korea g Central Officials Training Institute, Gwacheon, Gyeonggi-do, South Korea
Abstract Objective: Resilience has been considered as a protective factor against stress. Evaluating resilience in firefighters and rescue workers, who are frequently exposed to traumatic events, is important and relevant. This study examined the psychometric properties of the Korean version of the Connor–Davidson Resilience Scale-2 (CD-RISC2). Methods: Two-hundred twenty-two current professional firefighters and rescue workers were assessed by standardized, semi-structured clinical interviews and self-report questionnaires. Internal consistency, correlation with the CD-RISC, convergent validity, divergent validity, and predictive validity of posttraumatic stress disorder (PTSD) symptom severity were analyzed. Results: The CD-RISC2 demonstrated good internal consistency (α = 0.75), item-total correlation (r = 0.89–0.90), and convergent and divergent validity. The total score of the CD-RISC2 showed significant correlations with the subtotal of the remaining 23 CD-RISC items (r = 0.77, p b 0.001) and with the score of each CD-RISC item (r = 0.15–0.66, all p b 0.05). The magnitude of the relationship between the number of traumatic experiences and PTSD symptom severity was greater in the low resilience group than in the high resilience group (p for interaction = 0.002). The likelihood-ratio test confirmed that the model predicting PTSD symptom severity based on the CD-RISC2 total score was not improved by the inclusion of subtotal scores of the remaining 23 CD-RISC items (χ 2 = 0.31, p = 0.58). Conclusions: These results suggest that the CD-RISC2 would be a valuable tool in evaluating resilience quickly and efficiently in firefighters and rescue workers. © 2015 Elsevier Inc. All rights reserved.
1. Introduction
Financial support: This study was supported by the grant from the National Emergency Management Agency of Korea and the Medi-Star Program from the Korean Ministry of Health and Welfare (A112009). Disclosure: The authors declare that there are no financial conflicts of interest. ⁎ Corresponding author at: Room # 202, Posco-Building, Department of Brain and Cognitive Sciences, Ewha W. University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, South Korea. Tel.: +82 2 3277 6930; fax: +82 2 3277 6932. E-mail address: [email protected] (J.E. Kim). 1 These authors contributed equally to this work. http://dx.doi.org/10.1016/j.comppsych.2015.01.006 0010-440X/© 2015 Elsevier Inc. All rights reserved.
Resilience has been defined as a successful stress-coping ability that adaptively maintains physiological and psychological stability in the face of adversity [1]. It has been reported that resilience plays an influential role in buffering the adverse effects of traumatic events and protecting against the development of post-traumatic stress disorder (PTSD) or major depressive disorder (MDD) [1–4]. While people with high resilience recover quickly from psychological distress caused by trauma experiences, people with low resilience could not appropriately respond to post-traumatic stress [2]. A body of literature has shown that the degree of
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resilience, if measured accurately, can predict the development and treatment outcome of PTSD or MDD following trauma exposure [4,5]. Therefore, it is necessary to distinguish people with low resilience, who are vulnerable to mental illness after trauma exposure [1]. Firefighters and rescue workers are more frequently exposed to traumatic events than the general population due to the nature of their work [6]. Not surprisingly, high prevalence rates of PTSD and MDD in firefighters and rescue workers have consistently been reported. For instance, the point prevalence rates of probable PTSD and MDD in rescue workers exposed to the 9/11 World Trade Center disaster were 16.7% and 21.7%, respectively [7], whereas the lifetime prevalence rates of PTSD and MDD in the US general population were 7.8% and 16.2% [8,9]. The issue of mental health in firefighters and rescue workers is of critical importance because such concerns are not limited to affected individuals but are extended to public safety and welfare. Considering the protective role of resilience against PTSD or MDD symptoms [1,4], measuring resilience level in this occupation group would be important and helpful in identifying high-risk individuals for PTSD or MDD and providing them with early preventive interventions [5,6,10]. The Connor–Davidson Resilience Scale (CD-RISC), a widely used measure to quantify the level of self-perceived resilience [11], has shown its ability to identify target groups for interventions to prevent PTSD development [5]. The CD-RISC2, a shortened version of the CD-RISC, has an additional advantage of considerably decreased time to administer and measure the level of resilience with similar efficiency [12]. While the CD-RISC is composed of 25 items, the CD-RISC2 has only two items assessing whether the respondents are “able to adapt to change” and “tend to bound back after illness or hardships.” Among the general population and psychiatric patients including PTSD or MDD in the US, the CD-RISC2 demonstrated good test-retest reliability, convergent validity, divergent validity, and showed significant correlations with both the overall score and each item score of the CD-RISC, suggesting that the CD-RISC2 is a good representative of the CD-RISC [12]. The CD-RISC has shown good reliability and validity across various cultures including South Korea [13] and China [14], and has been applied to diverse populations, such as to war veterans [15] and to cancer patients [16]. However, the CD-RISC2 has not yet been validated in Asia or among firefighters and rescue workers. The purpose of the current study was to evaluate the psychometric properties of the Korean version of the CD-RISC2 in firefighters and rescue workers using semi-structured clinical interviews and self-report questionnaires. Our analyses included internal consistency, convergent validity, divergent validity, correlation with the CD-RISC, and predictive validity of PTSD symptom severity.
2. Methods 2.1. Participants Current firefighters and rescue workers were recruited from four fire stations in Seoul, South Korea. Participants were notified of guaranteed anonymity of personal information, and freedom to withdraw from the study at any point. Participants provided written informed consent before participating in the study. Ewha W. University Bioethics Committee reviewed and approved the study protocol. 2.2. Semi-structured interviews Semi-structured interviews were conducted by research clinicians who were trained by a board-certified psychiatrist (Y.J.). The interviews were conducted face-to-face in a private room in each of the fire stations where the participants work. Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV-Text Revision (DSM-IV-TR) was performed to diagnose PTSD or MDD [17]. The Hamilton Depression Rating Scale (HDRS) [18] and the Montgomery-Åsberg Depression Rating Scale (MADRS) [19] were used to assess depressive symptoms, and Hamilton Anxiety Rating Scale (HARS) to measure anxiety symptoms [20]. The Clinician-Administered PTSD Scale (CAPS) was used to measure PTSD symptom severity [21], and the Global Assessment of Functioning (GAF) Scale, which is included in DSM-IV-TR [22], to evaluate the overall psychological and socio-occupational functioning levels of the participants. The socioeconomic status, in addition, was evaluated using the Hollingshead Four-Factor Index of Socioeconomic Status [23]. 2.3. Self-report questionnaires The CD-RISC, a 25-item self-administered questionnaire, and the CD-RISC2, which is composed of items 1 and 8 from the CD-RISC, were used to assess resilience [11,12]. The total scores of the CD-RISC and the CD-RISC2 range from 0 to 100 and from 0 to 8, respectively. Higher total score in the CD-RISC or CD-RISC2 indicates greater resilience. The Beck Depression Inventory-II (BDI-II) [24] and the Beck Anxiety Inventory (BAI) [25] were used to measure depressive and anxiety symptom severity, respectively. To evaluate PTSD symptoms, the Impact of the Event Scale-Revised (IES-R) [26] and the Post-traumatic Stress Diagnostic Scale (PDS) [27] were used. The Life Event Checklist (LEC) was used to test whether the respondents have experienced 16 types of traumatic events in their lifetime [21]. To measure physical and mental functioning levels, the Short-Form 36-item Health Survey (SF-36) was used [28]. Alcohol use problems were evaluated using the Alcohol Use Disorder Identification Test (AUDIT) [29]. 2.4. Statistical analysis Independent t-test was used to compare the CD-RISC2 total scores between men and women. One-way analysis of
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variance (ANOVA) with post-hoc Scheffe's tests was performed to compare the CD-RISC2 total scores among the PTSD with MDD group, PTSD or MDD group, and the control group. Linear trend tests using logistic regression were used to evaluate the general trend in the CD-RISC2 total scores across the diagnostic groups. The relationship between the CD-RISC2 total score and participants' age and socioeconomic status was tested using linear regression. Internal consistency was evaluated using Cronbach's alpha. Item-total correlation was assessed by Pearson's correlation. The correlations between the CD-RISC2 total score and the subtotal scores of the remaining 23 CD-RISC items and between the CD-RISC2 total score and each CD-RISC item score were analyzed. Because resilience has been reported to be associated with depression, anxiety, and PTSD [1], convergent validity of the CD-RISC2 was evaluated by calculating Pearson's correlations between the CD-RISC2 total score and the scores of the HDRS, MADRS, HARS, CAPS, GAF, BDI-II, BAI, IES-R, PDS, and SF-36. Based on the report that the CD-RISC score was not associated with measures of alcohol use and problems, divergent validity was tested by correlating the total score of the CD-RISC2 and AUDIT [30]. Linear regression analysis assessed whether individuals with lower resilience level showed stronger relationship between the number of traumatic experiences reported in the LEC and PTSD symptoms. Participants with CD-RISC2 scores greater than or equal to the group mean score were categorized as high resilience group, while participants with CD-RISC2 scores less than the group mean score were categorized as low resilience group. Independent t-test was used to compare the current CAPS total scores between the low resilience group and the high resilience group. The regression analysis was conducted with the current CAPS total score as the dependent variable, and the number of traumatic experiences, the type of resilience groups, and their interaction term as the independent variables. Likelihood-ratio test was used to determine whether a model predicting the current CAPS total score based on the CD-RISC2 total score was not improved by the inclusion of subtotal scores from the remaining 23 CD-RISC items. All analyses were conducted using the STATA version 12.1 (StataCorp., College Station, TX). All statistical analyses were two-tailed with an alpha level of 0.05.
3. Results A total of 222 firefighters and rescue workers participated in the study (201 men and 21 women). The mean age was 40.2 ± 9.2 years. The average length of the service as a firefighter or a rescue worker was 12.7 ± 8.8 years. The numbers of participants who were diagnosed as PTSD with MDD and PTSD or MDD were 7 and 21, respectively. The mean CD-RISC2 score of the entire participants was 5.9 ± 1.3. The one-way ANOVA showed significant difference in
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terms of the mean CD-RISC2 scores across the diagnostic groups (F = 6.96, p b 0.001). Results from the post-hoc test are demonstrated in Table 1. The CD-RISC2 total score decreased from 6.0 in the control group to 5.1 in the PTSD or MDD group, and 4.4 in the PTSD with MDD group (p for linear trend b 0.001). The mean scores of men and women were 5.9 ± 1.3 and 5.8 ± 0.8 respectively, showing no significant difference between the groups (p = 0.79). The CD-RISC2 score was not associated with age (p = 0.31), but was positively associated with socioeconomic status of the participants (β = 0.19, R 2 = 0.02, p = 0.03). Cronbach's alpha of the CD-RISC2 was 0.75. Questions 1 (r = 0.89, p b 0.001) and 2 (r = 0.90, p b 0.001) were positively correlated with the total score of the CD-RISC2. The total score of the CD-RISC2 showed significant correlation with the subtotal of the remaining 23 CD-RISC items (r = 0.77, p b 0.001) and the score of each CD-RISC item (r = 0.15–0.66, all p b 0.05) (Table 2). Results from the tests to confirm convergent and divergent validity are summarized in Table 3. The mean CD-RISC2 score of the low resilience group (n = 71) was 4.4 ± 0.9 and that of the high resilience group (n = 151) was 6.5 ± 0.8. The difference in the current CAPS scores between the low resilience group (5.0 ± 11.1, n = 69) and the high resilience group (3.1 ± 6.5, n = 146) was not significant (p = 0.11). The magnitude of relationship between the number of traumatic experiences and the current CAPS scores was greater in the low resilience group than the high resilience group (t = −3.17, p for interaction = 0.002) (Fig. 1), indicating that PTSD symptom scores increased more steeply in the low resilience group compared to the high resilience group as the number of traumatic experiences increased. The likelihood-ratio test confirmed that the model predicting the current CAPS total score based on the CD-RISC2 total score was not improved by the inclusion of subtotal scores from the remaining 23 CD-RISC items (χ 2 = 0.31, p = 0.58).
4. Discussion To the best of our knowledge, the current study is the first to examine psychometric properties of the CD-RISC2 in Korean firefighters and rescue workers. The CD-RISC2 Table 1 The total score of the Connor–Davidson Resilience Scale-2 for each diagnostic group. a
CD-RISC2 score
PTSD with MDD group
PTSD or MDD group
Control group
4.4 ± 1.5 b
5.1 ± 1.5 b
6.0 ± 1.2
CD-RISC2 = Connor-Davidson Resilience Scale-2; MDD = major depressive disorder; PTSD = posttraumatic stress disorder. a The diagnosis was based on the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV-Text Revision. b p b 0.05 compared with the control group.
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Table 2 Correlations between the total score of the Connor-Davidson Resilience Scale-2 a and each item of the Connor-Davidson Resilience Scale. b CD-RISC item number 2 3 4 5 6 7 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
r
p
0.58 0.15 0.65 0.64 0.55 0.55 0.48 0.55 0.66 0.52 0.57 0.49 0.51 0.65 0.65 0.45 0.58 0.18 0.52 0.61 0.48 0.61 0.54
b0.001 0.03 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 b0.001 0.01 b0.001 b0.001 b0.001 b0.001 b0.001
CD-RISC = Connor-Davidson Resilience Scale. a The CD-RISC2 was composed of items 1 and 8 from the CD-RISC. b n = 221.
Table 3 Convergent and divergent validity of the Connor-Davidson Resilience Scale-2. Measure Convergent validity BAI a BDI-II b HDRS c HARS c MADRS c CAPS c PDS b IES-R d SF-36 mental component summary e SF-36 physical component summary e GAF f Divergent validity AUDIT a
r
p
−0.37 −0.45 −0.41 −0.39 −0.41 −0.15 −0.41 −0.35 0.47 0.36 0.33
b0.001 b0.001 b0.001 b0.001 b0.001 0.03 b0.001 b0.001 b0.001 b0.001 b0.001
−0.09
0.17
BAI = Beck Anxiety Inventory; BDI-II = Beck Depression Inventory-II; HDRS = Hamilton Depression Rating Scale; HARS = Hamilton Anxiety Rating Scale; MADRS = Montgomery-Åsberg Depression Rating Scale; CAPS = Clinician-Administered Posttraumatic Stress Disorder Scale; PDS = Post-Traumatic Stress Diagnostic Scale; IES-R = Impact of Event Scale-Revised; SF-36 = Short-Form 36-Item Health Survey; GAF = Global Assessment of Functioning; AUDIT = Alcohol Use Disorder Identification Test. a n = 221. b n = 222. c n = 215. d n = 220. e n = 219. f n = 207.
demonstrated satisfactory reliability and validity among firefighters and rescue workers. In addition, the explanatory power of the CD-RISC2 in predicting the current PTSD symptom severity was equivalent to that of the CD-RISC. The mean CD-RISC2 score of the entire sample (mean = 5.9) is lower than that of the US general population (mean = 6.9), but is similar to that of the family medicine outpatients in the US (mean = 6.0) [12]. This difference may have stemmed from the cultural differences, which are frequently observed for other psychometric assessment tools. For example, in responses to a Likert scale, East Asians chose the midpoint more often on items that involved expressing positive emotion than did Americans, who were more likely to demonstrate a positive emotion [31]. In addition, firefighters and rescue workers have frequently been exposed to extremely traumatic events, which may result in the decrease of the resilience level [32]. A significant decreasing trend is seen in the mean CD-RISC2 score from the control group to the PTSD or MDD group, and to the PTSD with MDD group, as shown in the previous report [12]. In terms of demographic characteristics, neither age nor sex had a significant correlation with the CD-RISC2 total score. These results are consistent with previous literatures [11,12]. Socioeconomic status was positively correlated with resilience. This result is supported by previous studies showing a positive association between resilience and education level, which is one of the most widely used measure of socioeconomic status in epidemiological studies [33,34]. Considering the fact that the CD-RISC2 consists of only two items, Cronbach's alpha of 0.75 was acceptable. The CD-RISC2 total score was significantly correlated with the subtotal of the remaining CD-RISC items and with each CD-RISC item score, suggesting that the CD-RISC2 is a reliable alternative measure of the CD-RISC. As we hypothesized, the CD-RISC2 demonstrated good convergent validity with the CD-RISC and other measures evaluating depression (HDRS, MADRS, BDI-II), anxiety (HARS, BAI), PTSD symptoms (CAPS, PDS, IES-R), overall health (SF-36), and overall functioning level (GAF). No association between the CD-RISC2 and the AUDIT provided evidence for the divergent validity, as we have expected. The likelihood-ratio test showed that the CD-RISC2 was as reliable as the CD-RISC in predicting PTSD symptom severity. Additionally, the CD-RISC2 successfully distinguished PTSD-vulnerable individuals by identifying low resilience group from high resilience group. These results suggest that the CD-RISC2, which is much shorter than the CD-RISC, may effectively substitute for the CD-RISC in firefighters and rescue workers. Although the results of the current study are promising, some limitations should be addressed. First, the participants were recruited only in Seoul, the capital city of South Korea, but firefighters and rescue workers in rural area may have different characteristics than those in metropolitan area. Second, test–retest reliability was not measured. Further study would be warranted to assess both short-term and
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Fig. 1. The relationship between the number of traumatic experiences and the severity of PTSD symptoms according to the resilience groups.Solid line shows the predicted CAPS total score by the LEC total score in the low resilience group, while dashed line is for the high resilience group. Participants with greater-than-mean CD-RISC2 total score and those with smaller were grouped as high and low resilience group, respectively.PTSD = post-traumatic stress disorder; CAPS = Clinician-Administered PTSD Scale; LEC = Life Events Checklist.
long-term test–retest reliabilities. Third, potential biomarkers of resilience such as neuropeptide Y were not used to validate the CD-RISC2 [35]. However, one of our strengths is that all subjects were thoroughly assessed by standardized, semi-structured clinical interviews as well as well-validated self-report measures. Resilience is not a fixed trait from birth. Instead, it can be conceptualized as a dynamic process that changes over time depending on the interactions between genetic variations and the environment [36]. Therefore, for effective prevention of PTSD and other mental disorders caused by frequent trauma exposure in firefighters and rescue workers, it would be highly important to monitor their levels of resilience on a regular basis. In an effort to prevent stress-induced mental disorders, resilience training programs could be developed and applied to firefighters and rescue workers. These programs have been proved to be efficacious in reducing stress and increasing the level of resilience among various groups with high occupational stress, such as in police officers and in military soldiers [37,38]. The CD-RISC2 was reliable and valid in measuring the level of resilience in the current study. Furthermore, the CD-RISC2 is not only very short but also as efficient as the CD-RISC. Therefore, the CD-RISC2 would be a valuable tool in evaluating resilience quickly and efficiently to protect mental health of firefighters and rescue workers. References [1] Agaibi CE, Wilson JP. Trauma, PTSD, and resilience: a review of the literature. Trauma Violence Abuse 2005;6:195-216. [2] Bonanno GA. Loss, trauma, and human resilience: have we underestimated the human capacity to thrive after extremely aversive events? Am Psychol 2004;59:20-8. [3] Bonanno GA, Galea S, Bucciarelli A, Vlahov D. What predicts psychological resilience after disaster? The role of demographics, resources, and life stress. J Consult Clin Psychol 2007;75:671-82.
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