The purpose of this study was to investigate the characteristics of psychological factors that are related to irritable bowel syndrome (IBS) and their effects on the quality of life (QOL) of firefighters in South Korea.
This study examined data collected from 1217 firefighters in South Korea. After identifying firefighters with IBS according to the Rome III diagnostic criteria for functional gastrointestinal disorders (FGIDs), we collected demographic data and psychological variables through self-administered questionnaires. In order to observe the distribution of the high-risk group in the Korean occupational stress scale (KOSS) subcategories, we conducted logistic multiple linear regression. The correlations between psychological factors and QOL were analyzed and we performed a stepwise regression analysis.
The groups (firefighters with and without IBS) showed differences by sex, working period, task, working pattern, Patient Health Questionnaire-9, Generalized Anxiety Disorder Questionnaire-7, Korean Occupational Stress Scale, Rosenberg's Self-Esteem Scale, and the World Health Organization Quality of Life-BREF. IBS risk was higher in the following KOSS subcategories: job demand (OR 1.79, 95% CI: 1.11–2.89), interpersonal conflict (OR 2.21, 95% CI: 1.25–4.33), organizational system (OR 1.87, 95% CI: 0.58–3.30), and lack of reward (OR 2.39, 95% CI: 1.08–5.26). The final regression model explained 42.6% of the variance in overall quality of life.
The findings of this study indicate that a number of psychological factors increase the likelihood of irritable bowel syndrome (IBS) and affect QOL. Therefore, when diagnosing IBS in the future, mental health aspects should be considered in addition to physical health.
In South Korea, firefighters are civil servants, whose duties involve emergency rescue, fire prevention, monitoring fire risk, and extinguishing fires. The functional aspects of firefighting duties can be classified into fire safety and volunteer functions. Moreover, firefighting duties have special characteristics in terms of risks, 24-hour shifts, and working environments, compared with the duties of other civil servants.
Nevertheless, there are very few studies of firefighters' exposure to risk or biological monitoring of firefighters; studies of the effect of firefighters' duties on their health are limited to an examination of occupational stress, posttraumatic stress disorder (PTSD), and physical diseases, including pulmonary dysfunction, respiratory symptoms, noise-induced deafness, musculoskeletal diseases, and cancer.
Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder characterized by chronic, relapsing abdominal pain or discomfort and disordered defecation.
Psychological factors such as stress play an important role in the onset of IBS.
Although the prevalence of IBS is high in firefighters and psychological factors are strongly associated with IBS manifestation and its aggravation, there are very few studies of the relationship between IBS and particular psychological factors. Therefore, this study investigated the characteristics of the psychological factors that are related to IBS and their effects on the quality of life of firefighters in South Korea.
Planning for the study began in July 2014 and data analysis was completed in March 2015. The fieldwork was conducted between September and October 2014. A total of 1,355 firefighters participated in the study. The exclusion criteria were as follows: 1) esophageal or gastric malignancy, 2) prior gastric surgery, 3) peptic ulcer disease, 4) chronic use of antacid medication, such as proton pump inhibitors or H2-receptor antagonists, for more than two months prior to survey, and 5) pregnancy. This resulted in 1,217 eligible firefighters for analysis (an eligibility rate of 89.81%).
We followed the Rome III diagnostic criteria to identify patients with FGIDS. The Rome III diagnostic criteria operate as a system to classify the functional gastrointestinal disorders of the digestive system (FGIDS) in which symptoms cannot be explained by the presence of structural or tissue abnormality, based on clinical symptoms.
We obtained each participant's demographic data and psychological variables through six questionnaires in total. After the researchers explained the purpose of this study, all participants provided written informed consent. This study was approved bythe Wonkwang University Hospital Institutional Review Board (IRB).
The Patient Health Questionnaire-9 (PHQ-9) is composed of nine items to identify depression.
The Generalized Anxiety Disorder Questionnaire-7 (GAD-7) is composed of seven items to identify anxiety. Each item is awarded 0–3 points and the maximum score is 21.
The Korean Occupational Stress Scale (KOSS) was developed to assess occupational stress. It is composed of eight domains: physical environment, job demand, insufficient job control, interpersonal conflict, job insecurity, organizational system, lack of reward, and occupational climate.
The Ways of Coping Checklist (WCCL) consists of four domains: problem-focused, seeking social support, emotion-focused, and wishful thinking.
The scale consists of ten items, five of which are worded positively and five negatively. The items are scored on a four-point scale ranging from 1 (strongly disagree) to 4 (strongly agree), with higher scores indicating higher self-esteem. Possible scores on the Rosenberg's Self-Esteem Scale (RSES) range from 10 to 40.
The World Health Organization Quality of Life-BREF (WH-OQOL-BREF) is a quality of life scale developed by the WH-OQOL Group. Itcomprises 26 items, which measure the following broad domains: physical health, psychological health, social relationships, and environment. Each item is awarded a score of 0–5 points, and higher scores signify higher quality of life.
We calculated the mean and standard deviation of continuous variables and the frequency and percentage of categorical variables. We employed chi-square tests to analyze the differences in the demographic data of participants with and without IBS (IBS-positive and IBS-negative, respectively). Independent t-tests were used to analyze the total scores of PHQ-9, GAD-7, KOSS, WCCL, RSES, and WHOQOL-BREF as continuous variables. We assessedthe IBS risk for each of the KOSS sub-categories by conducting a logistic regression analysis after controlling for sex, age, and education.We explored predictive variables that influenced quality of life through stepwise multiple regression analysis. The statistical analyses were performed using SPSS software (SPSS, Version 21; Chicago, IL, USA).
The chi-square tests of the demographic data revealed differences between the two groups by sex (χ2=16.649, df=1, p< 0.001), working period (χ2=8.546, df=3, p=0.041), task (χ2= 13.451, df=3, p=0.008), and working pattern (χ2=4.871, df=1, p=0.024). However, no differences by age, education, or marital status were observed (
In the independent t-tests conducted to identify differences between the IBS-positive and IBS-negative groups by psychological variables, significant differences were observed in PHQ-9 (t=-7.809, p<0.001), GAD-7 (t=-6.204, p<0.001), KOSS (t=-4.828, p<0.001), RSES (t=2.292, p=0.022), and WHOQOL-BREF (t=6.898, p<0.001). However, no significant difference between the two groups was observed for WCCL (
The major overlap among subjects with IBS was IBS-M: IBS-mixed type (47.7%) (
We adjusted for age and conducted logistic multiple linear regression in order to minimize the likelihood of misinterpretation of the results. In the high-risk group, the risk of IBS was higher in the following KOSS subcategories: job demand (OR 1.79, 95% CI: 1.11–2.89), interpersonal conflict (OR 2.21, 95% CI: 1.25–4.33), organizational system (OR 1.87, 95% CI: 0.58–3.30) and lack of reward (OR 2.39, 95% CI: 1.08–5.26). Statistically significant correlations were not observed in the other subcategories (
A stepwise multiple regression analysis was conducted to identify models that may predict quality of life in IBS-positive firefighters. We included in the multiple regression model variables that had significant correlations with QOL in the earlier bivariate analysis (age, working period, PHQ-9, GAD-7, KOSS, WCCL, and RSES). We also included task, which was a demographic variable that was expected to exert a significant influences on QOL. In the final regression model, PHQ-9 (β=-0.374, p<0.001), KOSS (β=-0.300, p<0.001), and RSES (β=0.188, p=0.018), which explained 42.6% of the variance in the total QOL, were included (
Various psychosocial factors put firefighters at a high risk of experiencing psychological and physical diseases. Psychosocial factors are very closely related to FGIDs, including IBS.
The incidence of IBS in this study was 9.1% (111 individuals). The prevalence of IBS reported in previous studies of the general population ranged between 4.4% and 19.4%. Despite the target population having a higher level of work-related stress in this study, the prevalence for IBS was relatively low. Previous studies have reported a substantially higher prevalence of IBS in females than in males. The relatively low prevalence of IBS in this study may be the consequence of the pre-ponderance (94%) of male participants.
Significant differences were observed between the IBS-positive and IBS-negative groups for the psychosocial factors of depression, anxiety, occupational stress, self-esteem, and quality of life. In a previous study by Fond et al.,
The findings of this study agree with previous studies in terms of context; moreover, by investigating differences in occupational stress, self-esteem, and stress coping styles that have not been investigated previously, the present study has broadened the scope of understanding of psychosocial factors in IBS.
The high-risk group in the subdomains of occupational stress including job demand, interpersonal conflict, organizational system, and lack of reward had a higher probability of IBS. Previous studies also reported that IBS has a very close association with stress. In a study by Koh et al.,
PHQ-9, KOSS, and RSES, which account for 42.6% of the variance in the total QOL, are factors that influence the quality of life of the IBS group. When Park et al.
The limitations of our study include that fact that, first, it was a cross-sectional study, so we could not assess effects over time. Second, we used self-reported data to evaluate psychological variables; therefore, there was the possibility of researchers' subjective bias, and there was no study of the severity of IBS symptoms. Third, since it was a population-based study, our study did not include endoscopy data. Finally, because we investigated firefighters, a specific occupational group, it is difficult to generalize the results to the characteristics of all IBS patients. Fifth, since the proportion of male subjects was extremely high (94%), we could not confirm differences by sex.
Nonetheless, this study was conducted with a large number of participants with IBS; the study also is advantageous in examining the influences of occupational stress, stress coping styles, and self-esteem, which have not been investigated previously. In addition, the study is significant, as it has suggested a new approach to the physical and psychological health of firefighters, which recently has become a social issue.
Future research into the influence of various psychosocial factors on IBS would expand present knowledge about the illness. Simultaneous physical and mental health approaches should be undertaken in the treatment of IBS. Moreover, more interest and research into the mental health of those employed in disaster control jobs, including firefighters, is necessary.
This research was supported by the National Research Foundation of Korea (NRF) Grant funded by the Ministry of Science, ICT & Future Planning for convergent research in Development program for convergence R&D over Science and Technology Liberal Arts (NRF-2016M3C1B6929822).
*p<0.05, **p<0.01, ***p<0.001. IBS: irritable bowel syndrome, N: number, M: male, F: female, EMS: emergency medical service
*p<0.05, ***p<0.001. IBS: irritable bowel syndrome, N: number, SD: standard deviation, PHQ-9: patient health questionnaire-9, GAD-7: generalized anxiety disorder-7, KOSS: Korean Occupational Stress Scale, WCCL: Ways of Coping Checklist, RSES: Rosenberg's Self-Esteem Scale, WHOQOL-BREF: World Health Organization Quality of life-BREF
N: number, IBC: irritable bowel syndrome, IBS-C: IBS-constipation, IBS-D: IBS-diarrhea, IBS-M: IBS-mixed type, IBS-U: IBS-unspecified
*p<0.05. IBS: irritable bowel syndrome
***p<0.001. IBS: irritable bowel syndrome, PHQ-9: patient health questionnaire-9, KOSS: Korean Occupational Stress Scale, RSES: Rosenberg's Self-Esteem Scale