Irritable bowel syndrome (IBS) is one of the most common functional bowel disorders, defined as the presence of abdominal pain or discomfort in association with altered bowel habits, without any organic damages to the intestine (Fan et al., 2006
). In most western countries, the prevalence of IBS is about 20%, while, in Asia, the prevalence varies from 2.9% to 15.6% (Chang and Lu, 2007
; Gwee et al., 2010
). IBS has been reported to account for up to 25% of the outpatient workload of a gastroenterologist (Butt et al., 2012
), and causes the significant direct and indirect costs related to medical investment, impaired work productivity, and quality of life (QOL).
The pathophysiology of IBS is still not completely understood, but psychological disorders may affect the onset and outcome of IBS in some patients. Studies have revealed that a much higher percentage (40%–60%) of IBS patients experience underlying psychological disorders than in the control groups without IBS (Butt et al., 2012
). Anxiety, depression, and somatization are more prevalent in IBS patients. Jerndal et al. (2010
) found that anxiety, which is an important mediating factor, greatly affects the severity of symptoms and QOL, and that reduction of anxiety can achieve a general improvement in IBS symptoms. Two recent studies concluded that depression and somatization were independently associated with IBS (Nicholl et al., 2008
; Savas et al., 2009
In recent years, the number of IBS research papers, relating to specific groups of people, has increased in China and the rest of the world. A survey of college and university students in North China found that IBS was common, and psychological disorders posed significant risks for IBS (Dong et al., 2010
). One study in the USA found that nurses, especially those working on rotating shifts, were at a high risk for developing IBS (Nojkov et al., 2010
). Zhen et al. (2006
) also demonstrated that IBS was common and severe among nurses working on rotating shifts, and sleep disturbance might be associated with IBS symptoms.
To our knowledge, the prevalence of IBS and associated factors, especially psychological factors, has not been investigated for nurses in China. The aims of this study were:
(1) To assess the prevalence of IBS in nurses;
(2) To evaluate whether factors, such as psychological disorders, are associated with IBS;
(3) To determine whether psychological disorders can influence the severity of symptoms of IBS and QOL.
2. Materials and methods
2.1. Study setting
This cross-sectional study was carried out from Nov. 2012 to Feb. 2013 in the China-Japan Friendship Hospital, Beijing, China. All nurses (450) employed in the clinical departments were invited to voluntarily complete questionnaires. The participants gave their written informed consent prior to data collection. The study was approved by the Ethics Committee of the China-Japan Friendship Hospital, Beijing, China.
2.2. Criteria of exclusion
Subjects with self-reported organic gastrointestinal disorder, abnormal laboratory findings, weight loss, anemia, bloody stools, family history of cancer, and other alarming signs, and those who were currently pregnant or had previously undergone gastro-intestinal surgery were excluded from the study.
2.3. Criteria for IBS patients
All subjects who were positive for IBS, using Rome III criteria, were categorized as IBS patients, while those who were found negative for IBS were categorized as controls.
2.4. Lifestyle factors
Questions about lifestyles, such as alcohol consumption, smoking, physical exercise, and night-shift work, were included in the questionnaire. In the assessment of the frequency of physical exercise in the questionnaire, “often” means the frequency of exercise at a minimum of three times a week with a minimum of 30 min for each session.
2.5.1. Chinese version of Rome III questionnaire
Rome III criteria were established by the Rome III Committee in 2006 (Longstreth et al., 2006
). The Chinese version has been widely used in China in recent years (Dong et al., 2013
). The diagnosis of IBS was based on the presence of abdominal pain or discomfort for at least three months during the previous six months, with at least two or more of the following conditions: symptoms associated with a change in frequency or form of stool, pain improved after defecation. Patients with IBS were divided into diarrhea-predominant IBS (IBS-D), constipation-predominant IBS (IBS-C), mixed IBS (IBS-M), and un-subtyped IBS (IBS-U) according to the proportion of hard and lumpy stools (Dong et al., 2013
2.5.2. ‘Severity of IBS’ questionnaire
The IBS severity questionnaire includes five items, which were assessed using the irritable bowel severity scoring system based on the presence and severity of perceived pain, the frequency of abdominal pain or discomfort, the presence and severity of abdominal distension, satisfaction with bowel habits, and the quantification of interference in the patient’s general lifestyle by these symptoms. Each item uses a 100-point scale and the final severity score is the sum of these scores (maximum up to 500). Patients were classified as having mild IBS (IBS severity score 75–175), moderately severe IBS (score 175–300), or severe IBS (score >300) (Francis et al., 1997
; Singh et al., 2012
2.5.3. Revised symptom checklist 90 (SCL-90-R) questionnaire
Psychopathological features were assessed with the SCL-90-R questionnaire, which contains 90 questions, on nine different aspects: somatization, depression, anxiety, obsessive-compulsive, interpersonal sensitivity, anger-hostility, phobic anxiety, paranoid ideation, and psychoticism. The general symptom index (GSI), which represents the average severity score of all 90 items on the questionnaire, is considered to be a reliable measure of psychological distress (Schauenburg and Strack, 1998
; Piacentino et al., 2011
2.5.4. Health-related QOL questionnaire
The disease-specific QOL for IBS (IBS-QOL) is a 34-item self-report questionnaire, which was designed to evaluate QOL in IBS patients. The questionnaire includes eight subscales, each item having a five-point response scale. The total score of the QOL (0–100) is a general parameter reflecting the health status of IBS patients. Higher total scores indicated better QOL (Dai et al., 2008
2.6. Statistical analysis
Statistical analysis was performed using the SPSS version 18.0.
Distributions of demographic characteristics and lifestyle factors were analyzed by Pearson’s χ
or Fisher’s exact test. The t
-test was used to compare the SCL-90-R scores between IBS and the control groups. Comparisons between different IBS subgroups were performed using the analysis of variance (ANOVA) test for continuous data. Spearman’s correlations between QOL and IBS severity, between SCL-90-R and IBS severity, and between QOL and SCL-90-R among IBS patients were determined. Logistic regression analysis was used to assess the possible risk factors. The odds ratio (OR) with a 95% confidence interval (CI) was calculated. Data are presented as mean±standard deviation (SD). P
<0.05 was considered statistically significant.
3.1. Response rate, demographic characteristics, and lifestyle factors of participants
Of the 450 nurses, 346 (76.9%) completed the surveys. Following the exclusion criteria, 340 nurses were included in the final analyses. Of the 340 nurses, 11 (3.2%) were men and 329 (96.8%) were women, with a mean age of (31.47±7.59) years. The demographic characteristics and lifestyle factors of participants are listed in Tables 1
. No difference in the demographic characteristics between IBS patients and the control group was found; however, there were statistically significant differences in lifestyle factors (night shift, alcohol consumption, and physical exercise) between the two groups.
Demographic characteristics of nurses
*Data are expressed as number (percentage)
| Minority groups
|Level of education
| Secondary school
| Junior college
| Master degree
Lifestyle factors in IBS patients and controls
*Data are expressed as number (percentage)
| >5 d/time
| ≤5 d/time
3.2. Prevalence of IBS and its subtypes
Of the 340 nurses, 59 (all women) fulfilled the criteria for having IBS. The prevalence of IBS was 17.4%, 9 cases were IBS-C (15.3%), 14 cases were IBS-D (23.7%), 23 cases were IBS-M (39.0%), and 13 cases were IBS-U (22.0%).
3.3. SCL-90-R scores in IBS patients and controls
IBS patients showed a significantly higher mean score for the GSI and nine subscale scores compared with the control group (P
<0.001; Table 3
). The GSI scores for the IBS-C, IBS-D, IBS-M, and IBS-U groups were 0.76±0.47, 0.71±0.45, 1.20±1.00, and 0.66±0.77, respectively. No statistically significant difference was found between IBS subtypes (F
Comparison of SCL-90-R scores between IBS patients and controls
GSI: general symptom index.
P<0.001 vs. control
Data are presented as mean±SD
3.4. QOL scores in IBS patients and controls
The QOL score for IBS patients was 77.18±21.93, and it was 88.44±11.89 (P
<0.001) for those without IBS. This indicated that the occurrence of IBS can influence their daily health and QOL. No difference was found between IBS subtypes (F
3.5. Distribution of IBS subtypes in IBS severity
Of the 59 IBS patients, 15 had mild IBS, 44 had moderately severe IBS, and none had severe IBS (Table 4
). Thus IBS was moderately severe in the majority of the cases.
Distribution of IBS subtypes in IBS severity
IBS-C: constipation-predominant IBS; IBS-D: diarrhea-predominant IBS; IBS-M: mixed IBS; IBS-U: un-subtyped IBS
3.6. Spearman’s correlation coefficients for IBS patients
Spearman’s correlations between SCL-90-R and IBS severity, SCL-90-R and QOL, QOL and IBS severity were analyzed. No significant correlations were found between them (Table 5
Spearman’s correlation coefficients for IBS patients
GSI: general symptom index; QOL: quality of life
|SCL-90-R score (GSI) and IBS severity
|SCL-90-R score (GSI) and QOL
|QOL and IBS severity
3.7. Risk factors for IBS
After the univariate analysis, to find independent risk factors for IBS, we entered factors (night shift, alcohol consumption, physical exercise, SCL-90-R score (GSI)) into a multivariable logistic regression analysis. The results showed that alcohol consumption (P
=0.010), low exercise level (P
<0.001), and a SCL-90-R score (GSI) (P
<0.001) were independently associated with IBS (Table 6
Evaluation of risk factors for IBS by multi-variate logistic regression analysis
SE: standard error; CI: confidence interval; GSI: general symptom index
||Odds ratio (95% CI)
|SCL-90-R score (GSI)
To our knowledge, this was the first investigation using Rome III criteria to assess the prevalence and the associated psychological and lifestyle factors of IBS in nurses in China. The prevalence of IBS in the study was 17.4%, and 39% of those with IBS had IBS-M. The SCL-90-R scores were significantly higher for IBS patients than for the control group.
It is likely that changing lifestyles and the rapid changes in the socioeconomic environment contribute to the increased prevalence of IBS in Asian countries. Different eating habits, genetic factors, and socio-cultural backgrounds may result in different prevalence rates, based on investigations conducted from different perspectives in China. A population-based study estimated the prevalence of IBS as 7% in Guangdong, China (Chang and Lu, 2007
). The prevalence of IBS among undergraduates in Southeast China was reported as 10.4% using Rome III criteria (Dai et al., 2008
), and similarly, Dong et al. (2010
) reported the prevalence of IBS in college and university students in North China as 7.85%. Our survey suggests that nurses have an even higher prevalence of IBS. Nojkov et al. (2010
) found similar results in nurses in the USA, in which the prevalence of IBS was 48% in rotating-shift nurses and 31% in day-shift nurses. A study from Singapore found the prevalence of functional bowel disorders to be 38% in nurses working rotating shifts and 20% in those working day shifts (Zhen et al., 2006
). Using Rome III criteria and only nurses being included may explain this higher prevalence. Moreover, because of their particular working conditions (experiencing more of the various psychosocial stressors, heavy workloads, and lack of rest time), nurses may be an especially high-risk population for IBS.
In our survey, the SCL-90-R scores were high in nurses with IBS, indicating that psychosocial disorders have some influence on the clinical course of IBS. Psychiatric symptoms and psychiatric disorders are common among IBS patients, and the most frequent psychiatric diagnoses in IBS are depression, anxiety, and somatoform disorders (Surdea-Blaga et al., 2012
). Savas et al. (2009
) reported that the prevalence of depression in IBS patients was 31.4% compared with 17.5% in the control group. In a community study, anxiety was found to be more common in IBS patients (Lee et al., 2009
). Sykes et al. (2003
) observed that anxiety tends to precede IBS onset and plays an important role in the development of IBS. In a South Australian study, Mikocka-Walus et al. (2008
) found that depression and anxiety were common in subjects with IBS symptoms. An excessive tendency to somatization was reported in population-based studies and in clinical studies (Locke et al., 2004
). Somatization, together with depression and anxiety, may explain the extra-gastrointestinal symptoms in IBS patients, such as headaches, constant fatigue, and urinary symptoms (Zimmerman, 2003
). Increasing attention has been given to the influence of psychosocial factors in the pathogenesis, severity, course, and outcome of IBS. The bi-directional connection between the gastrointestinal tract and the brain is through the brain-gut axis, and psychosocial factors can lead to dysfunction of the brain-gut axis, which in turn causes dysfunction of the gut (Jones et al., 2006
In the present study, the findings suggest that the nurses with low exercise levels were more likely to develop IBS, which is consistent with Dong et al. (2010
). The chronic abdominal discomfort or pain may reduce the motivation of nurses to exercise, or they may be too busy to do it (Dong et al., 2010
). Our survey indicates that alcohol consumption is a risk factor for IBS patients. We speculate that alcohol can increase intestinal membrane permeability and visceral sensitivity, thus changing the normal physiological function of the gut. Our findings that there were no statistically significant differences in QOL and SCL-90-R scores between IBS subtypes are consistent with the results of other previous research (Katsinelos et al., 2009
; Park et al., 2009
; Jamali et al., 2012
). However, Eriksson et al. (2008
) found that QOL was lower in IBS-C and IBS-M when compared with other subtypes, and showed that the mean psychosocial scores were higher in IBS-M and IBS-C compared with IBS-D. This can be explained by the different types of questionnaires, cultures, and selected subjects. In our study, IBS was moderately severe in the majority of cases, and no statistically significant correlations between SCL-90-R and IBS severity, between SCL-90-R and QOL, or between QOL and IBS severity were found. This indicated that, in nurses with IBS, psychosocial factors were not associated with QOL or severity of symptoms, and that severity of symptoms did not affect QOL. If we followed the nurses with IBS for long enough periods, however, IBS subtypes may change into one another, and comparisons of these parameters might change (Mearin et al., 2004
A number of limitations of our study should be taken into consideration. First, the survey was restricted to nurses, which might influence the generalizability of our results. Second, the study was based on self-reporting questionnaires, without using upper gastrointestinal endoscopy and colonoscopy to exclude structural intestinal diseases. Third, there were only 11 men in our study, so the findings may not be generally applicable to male nurses.
In summary, this study showed that the prevalence of IBS in nurses is 17.4%. Psychological disorders and certain related lifestyle factors are probably the elements that make nurses particularly susceptible to the development of IBS. Further studies should pay more attention to psychiatric evaluation and treatment together with rectification of some unhealthy aspects of current and past lifestyles.
* Project supported by the National Natural Science Foundation of China (No. 81070299)Compliance with ethics guidelines Liang LIU, Qi-fan XIAO, Yan-li ZHANG, and Shu-kun YAO declare that they have no conflict of interest.
Butt, A.S., Salih, M., Jafri, W., 2012. Irritable bowel syndrome and psychiatric disorders in Pakistan: a case control study. Gastroenterol Res Pract
Chang, F.Y., Lu, C.L., 2007. Irritable bowel syndrome in the 21st century: perspectives from Asia or South-east Asia. J Gastroenterol Hepatol
Dai, N., Cong, Y., Yuan, H., 2008. Prevalence of irritable bowel syndrome among undergraduates in Southeast China. Dig Liver Dis
Dong, Y.Y., Zuo, X.L., Li, C.Q., 2010. Prevalence of irritable bowel syndrome in Chinese college and university students assessed using Rome III criteria. World J Gastroenterol
Dong, Y.Y., Chen, F.X., Yu, Y.B., 2013. A school-based study with Rome III criteria on the prevalence of functional gastrointestinal disorders in Chinese college and university students. PLoS ONE
Eriksson, E.M., Andren, K.I., Eriksson, H.T., 2008. Irritable bowel syndrome subtypes differ in body awareness, psychological symptoms and biochemical stress markers. World J Gastroenterol
Fan, Y.J., Chen, S.J., Yu, Y.C., 2006. A probiotic treatment containing Lactobacillus
improves IBS symptoms in an open label trial. J Zhejiang Univ-Sci B (Biomed & Biotechnol)
Francis, C.Y., Morris, J., Whorwell, P.J., 1997. The irritable bowel severity scoring system: a simple method of monitoring irritable bowel syndrome and its progress. Aliment Pharmacol Ther
Gwee, K.A., Bak, Y.T., Ghoshal, U.C., 2010. Asian consensus on irritable bowel syndrome. J Gastroenterol Hepatol
Jamali, R., Jamali, A., Poorrahnama, M., 2012. Evaluation of health related quality of life in irritable bowel syndrome patients. Health Qual Life Outcomes
Jerndal, P., Rinqstrm, G., Agerforz, P., 2010. Gastrointestinal-specific anxiety: an important factor for severity of GI symptoms and quality of life in IBS. Neurogastroenterol Motil
Jones, M.P., Dilley, J.B., Drossman, D., 2006. Brain-gut connections in functional GI disorders: anatomic and physiologic relationships. Neurogastroenterol Motil
Katsinelos, P., Lazaraki, G., Kountouras, J., 2009. Prevalence, bowel habit subtypes and medical care-seeking behaviour of patients with irritable bowel syndrome in Northern Greece. Eur J Gastroenterol Hepatol
Lee, S., Wu, J., Ma, Y.L., 2009. Irritable bowel syndrome is strongly associated with generalized anxiety disorder: a community study. Aliment Pharmacol Ther
Locke, G.R., Weaver, A.L., Melton, L.J., 2004. Psychosocial factors are linked to functional gastrointestinal disorders: a population based nested case-control study. Am J Gastroenterol
Longstreth, G.F., Thompson, W.G., Chey, W.D., 2006. Functonal bowel disorders. Gastroenterology
Mearin, F., Baro, E., Roset, M., 2004. Clinical patterns over time in irritable bowel syndrome: symptom instability and severity variability. Am J Gastroenterol
Mikocka-Walus, A.A., Turnbull, D.A., Andrews, J.M., 2008. Psychological problems in gastroenterology outpatients: a South Australian experience. Psychological co-morbidity in IBD, IBS and hepatitis C. Clin Pract Epidemiol Ment Health
Nicholl, B.I., Halder, S.L., Macfarlane, G.J., 2008. Psychosocial risk markers for new onset irritable bowel syndrome—results of a large prospective population-based study. Pain
Nojkov, B., Rubenstein, J.H., Chey, W.D., 2010. The impact of rotating shift work on the prevalence of irritable bowel syndrome in nurses. Am J Gastroenterol
Park, J.M., Choi, M.G., Kim, Y.S., 2009. Quality of life of patients with irritable bowel syndrome in Korea. Qual Life Res
Piacentino, D., Cantarini, R., Alfonsi, M., 2011. Psychopathological features of irritable bowel syndrome patients with and without functionaldyspepsia: a cross sectional study. BMC Gastroenterol
Savas, L.S., White, D.L., Wieman, M., 2009. Irritable bowel syndrome and dyspepsia among women veterans: prevalence and association with psychological distress. Aliment Pharmacol Ther
Schauenburg, H., Strack, M., 1998. The symptom checklist-90-R (SCL-90-R) for presenting statistically and clinically significant psychotherapy outcome. Psychother Psychosom Med Psychol
Schauenburg, H., Strack, M., 1999. Measuring psychotherapeutic change with the symptom checklist SCL 90 R. Psychother Psychosom
Singh, P., Agnihotri, A., Pathak, M.K., 2012. Psychiatric, somatic and other functional gastrointestinal disorders in patients with irritable bowel syndrome at a tertiary care center. J Neurogastroenterol Motil
Surdea-Blaga, T., Băban, A., Dumitrascu, D.L., 2012. Psychosocial determinants of irritable bowel syndrome. World J Gastroenterol
Sykes, M.A., Blanchard, E.B., Lackner, J., 2003. Psychopathology in irritable bowel syndrome: support for a psychophysiological model. J Behav Med
Zhen, L.W., Ann, G.K., Yu, H.K., 2006. Functional bowel disorders in rotating shift nurses may be related to sleep disturbances. Eur J Gastroenterol Hepatol
Zimmerman, J., 2003. Extraintestinal symptoms in irritable bowel syndrome and inflammatory bowel diseases: nature, severity, and relationship to gastrointestinal symptoms. Dig Dis Sci
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