Gastroenterology Research and Practice
Volume 2014 (2014), Article ID 124261, 8 pages
http://dx.doi.org/10.1155/2014/124261

Research Article

A School-Based Study of Irritable Bowel Syndrome in Medical Students in Beijing, China: Prevalence and Some Related Factors

Yang Liu,1,2 Liang Liu,1,3 Yi Yang,1,2 Yuxi He,1,2 Yanli Zhang,¹ Miao Wang,¹ Shuo Chen,1,3 and Shukun Yao1,3

¹Gastroenterology Department, China-Japan Friendship Hospital, Beijing 100029, China
²Beijing University of Chinese Medicine, Beijing 100029, China
³Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100073, China

Received 4 August 2014; Accepted 21 September 2014; Published 13 October 2014

Academic Editor: Peter J. Whorwell

Copyright © 2014 Yang Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

Purpose. To investigate the prevalence and some related factors about irritable bowel syndrome (IBS) in medical students. Methods. A cross-sectional study was carried out from February 2014 to Jun 2014 in Beijing University of Chinese Medicine, Beijing, China. All participants were asked to completed self-administered questionnaires. Results. Seven hundred and sixty-seven medical students ( years, 25.6% males) completed the survey. The prevalence of IBS was 33.3%, with a high prevalence in women (36.1%). Among the IBS patients, 112 cases were IBS-M (43.9%) and 77.6% had moderately severe IBS. There were no statistical differences between control group and IBS patients in anxiety and depression scores (). The total score of Pittsburgh sleep quality index (PSQI) was significantly higher for medical students with IBS and 35.5% of IBS patients had severe sleep disorder; the scores of child trauma questionnaire (CTQ) and student-life stress inventory (SLSI) were also higher in IBS patients. Sex and sleep disorder were independently associated with IBS (OR, 1.914, 95%CI, 1.281–2.860; OR, 1.143, 95%CI, 1.074–1.216). Conclusion. Our study has many valuable findings and they may provide valuable suggestions for the necessary intervention and treatment measures towards medical students.

1. Introduction

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder, characterized by abdominal pain or discomfort in association with altered bowel habits [1]. IBS is common in the general population; the prevalence of this disease in European countries was about 20%; in recent years, the morbidity of Asian countries is rising year by year, which is near to that in Western countries [2–5]. Without any biological markers, the diagnosis of IBS mainly depends on the patient’s symptoms. According to Rome III criteria, IBS patients were subdivided into diarrhea-predominant IBS (IBS-D), constipation-predominant IBS (IBS-C), mixed type IBS (IBS-M), and unsubtyped IBS (IBS-U) [6].

Although the pathophysiology of IBS is unclear, gender, diet, lifestyle, psychiatric disorders, sleep problems, early adverse life events (EALs), and stress have been considered as risk factors to IBS, but they are controversial [3–5, 7–15]. Medical students are a special group, characterized by tremendous cognitive and emotional changes. At the same time, due to massive study and exams load, increasing fierce competition for jobs, undesirable living, and eating habits, medical students may be an especially high-risk population for IBS [3]. In recent years, the number of IBS research papers, relating to medical students, has increased in China and the rest of the world [3–5, 16]; however, to the best of our knowledge, no comprehensive survey (including prevalence, diet, lifestyle, psychiatric disorders, sleep problems, EALs, and stress) about IBS using Rome III criteria has been carried out on medical students in Beijing, China, nowadays. The information about prevalence and related factors in medical students may provide targeted recommendations for the treatment of IBS, which can effectively improve the clinical symptoms of IBS patients and enhance their learning efficiency and quality of life.

So the aims of this study were (1) to investigate the prevalence of IBS in medical students according to Rome III criteria and the related factors with IBS and (2) to evaluate the risk factors associated with the disorder.

2. Materials and Methods

2.1. Study Setting and Ethics Statement

This cross-sectional study was carried out from February 2014 to June 2014 in Beijing University of Chinese Medicine, Beijing, China. All participants gave their written informed consent prior to completing self-administered questionnaires. The study protocol was approved by the ethics committee of the China-Japan friendship hospital, Beijing, China.

2.2. Participants

This study included medical students from the first to the seventh year, and we employed a multistage stratified random sample method [4, 8]. Using the following formula, , where (error of the first kind), % (estimated prevalence), , and (permissive error), the expected minimal sample size for this study was 683. According to the 90% response rate, the number of students should be 759. To ensure reliability, we proceeded to recruit 843 medical students into the study.

2.3. Criteria of Exclusion

Subjects with self-reported organic gastrointestinal disorder, family history of cancer, weight loss, anemia, bloody stools, abnormal laboratory findings, other alarming signs, and those who had previously undergone gastrointestinal surgery were excluded from our study [1].

2.4. Questionnaires

2.4.1. Personal General Information, Lifestyle, and Eating Habits

Personal data, such as sex, age, height, weight, and lifestyle and eating habits, such as exercise frequency, smoking, and alcohol consumption, were included in the questionnaire. With the grade, low means the students from the first to the fourth year, and high means from the fifth to the seventh year.

2.4.2. Chinese Version of Rome III Criteria for Diagnosis of IBS

The Chinese version of Rome III criteria for diagnosis of IBS has been widely used [1, 17, 18]. The diagnosis of IBS was based on the presence of abdominal pain or discomfort which had to occur at least 3 days per month 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 and 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 unsubtyped IBS (IBS-U) according to the proportion of hard and lumpy stools.

2.4.3. “Severity of IBS” Questionnaire

The IBS severity questionnaire includes five items: the severity of perceived pain, the presence and severity of abdominal distension, the frequency of abdominal pain or discomfort, satisfaction with bowel habits, and the quantification of interference in the patient’s general lifestyle by these symptoms. Each item has a 100-point scale from 20 to 100 score and the total severity score is the sum of the five items. Patients were classified as having mild IBS (IBS severity score 75–175), moderately severe IBS (score 175–300), and severe IBS (score > 300) [19, 20].

2.4.4. Hospital Anxiety and Depression Scale (HADS)

HADS was widely used in China [17, 18]. It has 14 questions (with two 7-item subscales) and was used in estimating the emotional disorders of anxiety and depression status in patients. For each subscale, the result fell into 3 grades as follows: normal cases (0–7), borderline cases (8–10), and severe cases (over 11) [17, 18].

2.4.5. Pittsburgh Sleep Quality Index (PSQI)

PSQI is a 19-item, self-administered questionnaire [21]. It has been widely used to assess the sleep quality of subjects [8]. The contents of the PSQI include seven items: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep inducers, and daytime dysfunction. Each item uses a three-point response scale, the total score was used to calculate the PSQI global index (ranging from 0 to 21); a total score > 5 means poor sleepers, and when the total score is up to or greater than 8, it means a severe sleep disorder.

2.4.6. Child Trauma Questionnaire (CTQ)

CTQ, which has 28 items, was developed by Bernstein et al. [22]. CTQ consists of five subscales (emotional abuse, physical abuse, sexual abuse, emotional neglect, and physical neglect, each subscale has five items) to evaluate the degree of child trauma (one type of EALs) and three items for validity evaluation. Each item has a 5-point scale from 1 to 5 score; the total score ranges from 25 to 125 [23].

2.4.7. Student-Life Stress Inventory (SLSI)

SLSI was designed by Gadzella [24]. SLSI has 51 items with five stress categories (frustration, conflicts, pressures, changes, and self-imposed) and four categories of reactions to stressors. Each item uses a 5-point scale; the total score is the sum of the nine categories. The purpose of the SLSI was to assess the mean responses to different stressors and reactions to stressors among students [24].

2.5. Statistical Analysis

Statistical analysis was performed using the SPSS version 19.0 (IBM Corporation, NY, USA). Categorical variables were analyzed by Pearson’s or Fisher’s exact test. The -test was used to compare group differences for continuous variables; data is presented as mean ± SD. Logistic regression analysis was used to assess the possible risk factors. The odds ratio (OR) with a 95% confidence interval (CI) was calculated. All calculated values were two-tailed and was considered statistically significant.

3. Results

3.1. Response Rate, Overall Characteristics, Lifestyle, and Eating Factors of Participants

Of the 843 medical students, 767 (91.0%) completed the survey, and they were included in the final analyses. The age of the medical students ranged from 18 to 27 years, with a mean age of years; 196 (25.6%) were males and 571 (74.4%) were females. The demographic characteristics, lifestyle, and eating factors of participants are listed in Tables 1 and 2. It is apparent from Table 2 that significant difference was found between IBS and control groups in seafood diet; IBS patients had a lower frequency in this item.

Table 1: Characteristics of medical students with or without IBS n (%).

Total
()
IBS
()
Non-IBS
()

value

Sex

8.151
0.005

    Male
196 (25.6%)
49 (19.2%)
147 (28.8%)

    Female
571 (74.4%)
206 (80.8%)
365 (71.2%)

Age (yr)

−2.267
0.024

Height (m)

−2.975
0.005

Weight (kg)

−0.816
0.459

BMI (kg/m²)

0.862
0.389

Nationality

0.086
0.881

    Han
713 (93.0%)
238 (93.3%)
475 (92.8%)

    Minority
54 (7.0%)
17 (6.7%)
37 (7.2%)

Grade

1.617
0.220

    Low
251 (32.6%)
91 (35.7%)
160 (31.1%)

    High
516 (67.4%)
164 (64.3%)
352 (68.9%)

IBS: irritable bowel syndrome.

Table 2: Lifestyle and eating habits of medical students with or without IBS n (%).

Total
()
IBS
()
Non-IBS
()

value

Smoking

0.130
0.790

    No
750 (97.9%)
249 (97.6%)
502 (98.0%)

    Yes
17 (2.1%)
6 (2.4%)
10 (2.0%)

Alcohol consumption

2.201
0.333

    No
721 (94.1%)
244 (95.7%)
478 (93.2%)

    Yes
45 (5.9%)
11 (4.3%)
34 (6.7%)

Exercise frequency

2.280
0.516

    <1 time/week
258 (33.7%)
79 (31.0%)
179 (35.0%)

    1 or 2 times/week
289 (37.7%)
104 (40.8%)
185 (36.2%)

    ≥3 times/week
220 (28.6%)
72 (28.2%)
148 (28.8%)

Coffee

2.504
0.475

    Seldom
713 (93.0%)
236 (92.9%)
476 (93.0%)

    Often
54 (7.0%)
19 (7.1%)
36 (7.0%)

Carbonated beverage

2.556
0.279

    Seldom
618 (80.7%)
209 (82.0%)
409 (80.0%)

    Often
149 (19.3%)
46 (18.0%)
103 (20.0%)

Eating fruits

1.072
0.585

    Seldom
184 (24.0%)
58 (22.7%)
126 (24.7%)

    2–6 times/week
409 (53.4%)
134 (52.5%)
275 (53.8%)

    Almost every day
174 (22.6%)
63 (24.7%)
111 (21.5%)

Pure milk drinking

0.206
0.902

    Seldom
429 (56.0%)
143 (56.1%)
286 (56.0%)

    2–6 times/week
266 (34.7%)
90 (35.3%)
176 (34.4%)

    Almost every day
72 (9.3%)
22 (8.6%)
50 (9.6%)

Acidophilus milk

1.751
0.417

    Seldom
354 (46.2%)
113 (44.3%)
241 (47.2%)

    2–6 times/week
371 (48.4%)
131 (51.4%)
240 (47.0%)

    Almost every day
42 (5.4%)
11 (4.3%)
31 (5.8%)

Spicy food

1.518
0.468

    Seldom
248 (32.4%)
76 (29.8%)
172 (33.7%)

    2–6 times/week
421 (55.0%)
148 (58.0%)
273 (53.4%)

    Almost every day
98 (12.7%)
31 (12.2%)
67 (12.9%)

Greasy food

2.661
0.447

    Seldom
299 (39.0%)
96 (37.6%)
203 (39.7%)

    2–6 times/week
366 (51.7%)
132 (51.8%)
264 (51.7%)

    Almost every day
72 (9.3%)
27 (10.6%)
45 (8.6%)

Meat (pig, cattle, or sheep)

1.688
0.430

    Seldom
132 (17.2%)
39 (15.3%)
93 (18.2%)

    2–6 times/week
459 (59.9%)
152 (59.6%)
307 (60.1%)

    Almost every day
176 (22.9%)
64 (25.1%)
112 (21.7%)

Fish

2.807
0.246

    Seldom
470 (61.4%)
167 (65.5%)
303 (59.3%)

    2–6 times/week
287 (37.5%)
85 (33.3%)
202 (39.5%)

    Almost every day
10 (1.2%)
3 (1.2%)
7 (1.2%)

Seafood diet

11.097
0.025

    Seldom
681 (88.9%)
236 (92.5%)
445 (87.1%)

    2–6 times/week
81 (10.6%)
17 (6.7%)
64 (12.5%)

    Almost every day
5 (0.5%)
2 (0.8%)
2 (0.4%)

Salty food

1.700
0.194

    Not preferred
381 (49.6%)
118 (46.3%)
263 (51.3%)

    Preferred
386 (50.4%)
137 (53.7%)
249 (48.7%)

The days of regular diet

3.295
0.348

    6-7 days/week
427 (55.5%)
134 (52.5%)
291 (56.9%)

    3–5 days/week
298 (38.9%)
106 (41.6%)
192 (37.6%)

    ≤2 days/week
42 (5.6%)
15 (5.9%)
28 (5.5%)

IBS: irritable bowel syndrome.

3.2. Prevalence of IBS

Of the 767 medical students, 255 fulfilled the criteria for having IBS, the prevalence of IBS was 33.3%, for females, the prevalence was 36.1% (206/571), and for males, 25.0% (49/196) of the cases were found to be positive. At the same time, we found that, for women, the students with low grade had a higher prevalence of IBS (45.9%, 67/146), and the high grade was 32.8% (139/425) (); for men, no statistical difference was found (23.1%, 24/104 versus 27.2%, 25/92 ). Among the IBS patients, 112 cases were IBS-M (43.9%), 79 cases were IBS-D (31.0%), 49 cases were IBS-U (19.2%), and 15 cases were IBS-C (5.9%). Female predominance was IBS-M (45.1%), and male predominance was IBS-D (44.9%). Of the 255 IBS patients, 20.4% were mild IBS, 77.6% had moderately severe IBS, and 2.0% were severe cases.

3.3. HADS and PSQI Scores in IBS Patients and Controls

The anxiety and depression scores in IBS patients were and , for control group, there were and , and no statistical differences were found (Table 3). However, for females, IBS patients had a higher score than healthy controls in anxiety ( versus , ).

Table 3: Comparing mean scores of the HADS and PSQI between IBS and non-IBS.

IBS
Non-IBS

value

HADS

    Anxiety

1.382
0.167

    Depression

0.510
0.610

PSQI (total)

6.015
<0.001

HADS: hospital anxiety and depression scale; PSQI: Pittsburgh sleep quality index; IBS: irritable bowel syndrome.

As shown in Table 3, the total score of the PSQI was significantly higher for medical students with IBS than for those without IBS; on the other hand, for females, the score was in IBS cases and in controls (); for males, the scores were and (). According to the PSQI score standard, the prevalence of severe sleep disorder was 35.5% in IBS patients and 17.8% in subjects without IBS.

3.4. CTQ and SLSI Scores in IBS and Control Groups

Table 4 illustrates that the score of emotional neglect was much higher in IBS patients (); the other 4 subscales and the total score of CTQ were also higher in IBS group, but there were no significant differences.

Table 4: The CTQ scores between IBS and non-IBS.

IBS
Non-IBS

value

Emotional abuse

1.586
0.113

Physical abuse

1.118
0.264

Sexual abuse

0.337
0.736

Emotional neglect

2.004
0.045

Physical neglect

0.505
0.614

CTQ (total)

1.781
0.075

CTQ: child trauma questionnaire; IBS: irritable bowel syndrome.

For SLSI, the total score of SLSI and the other seven categories showed statistical differences between IBS and control groups (Table 5). Similar results were obtained in females (Table 6); however, for males, no differences were found in the total score of SLSI and nine categories between IBS patients and health group.

Table 5: The SLSI scores between IBS and non-IBS.

IBS
Non-IBS

value

(I) Stressors

        Frustration

2.139
0.033

        Conflict

3.197
0.001

        Pressure

3.349
0.001

        Change

3.598
<0.001

        Self-imposed

1.036
0.301

(II) Reaction to stressors

        Physiological

2.780
0.006

        Emotional

3.232
0.001

        Behavioral

2.220
0.027

        Cognitive

−0.722
0.471

(III) Totals

3.936
<0.001

SLSI: student-life stress inventory; IBS: irritable bowel syndrome.

Table 6: The SLSI scores between IBS and non-IBS in females.

IBS
Non-IBS

value

(I) Stressors

        Frustration

2.139
0.039

        Conflict

3.197
<0.001

        Pressure

3.349
<0.001

        Change

3.598
<0.001

        Self-imposed

1.036
0.217

(II) Reaction to stressors

        Physiological

4.058
<0.001

        Emotional

3.582
<0.001

        Behavioral

2.958
0.003

        Cognitive

−0.189
0.850

(III) Totals

4.657
<0.001

SLSI: student-life stress inventory; IBS: irritable bowel syndrome.

3.5. Risk Factors for IBS

After the univariate analysis, to find independent risk factors for IBS, multivariable logistic regression analysis was performed. Sex and sleep disorder were independently associated with IBS (Table 7).

Table 7: Evaluation of risk factors for irritable bowel syndrome by multivariate logistic regression analysis.

Variables

Standard error
Wald
Odds ratio
95% CI
value

Lower
Upper

Sex
0.649
0.205
10.026
1.914
1.281
2.860
0.002

PSQI
0.134
0.032
17.934
1.143
1.074
1.216
<0.001

CI: confidence interval.

Table 7 shows the evaluation of risk factors for irritable bowel syndrome by multivariate logistic regression analysis.

4. Discussion

To our knowledge, this was the first comprehensive survey using the Rome III criteria to assess the prevalence of some related factors in medical students in Beijing, China. In this study, the prevalence of IBS in medical students was 33.3%, 43.9% of those with IBS had IBS-M, and the majority of the patients (77.6%) had moderately severe IBS. IBS patients had a significantly higher PSQI score together with a 35.5% prevalence of severe sleep disorder. In the assessments of CTQ and SLSI, the scores in patients were also higher.

Our survey suggests that medical students have an even higher prevalence of IBS, more female students suffered from IBS, and gender may be a risk factor of this disease. The results are in line with that in previous studies [3, 4]. Considering the special living environment (countless examinations and heavy clinical practice in hospital) together with lacking the ability of self-adjustment and adaptation, medical students may be an especially high-risk population for IBS. At the same time, we found that female students had a higher prevalence than male students, speculating that the difference of hormone levels may play a role [25]. In addition, women are more likely to have mental problems and sleep disorders, which may be related to the high prevalence of IBS. For females, the students with low grade had a higher prevalence of IBS, which is contrary to the previous study [4]. Differences in study groups and evaluation standard may explain the relative lacking of medical knowledge; low health care seeking rate may also give rise to the high prevalence of IBS.

Unfortunately, in the survey about eating habits and lifestyles, we only found significant difference in seafood diet between IBS and control groups; IBS patients had a lower frequency in this item. It may be true that some IBS patients had food intolerance. Gastrointestinal symptoms appeared after eating seafood, which made them artificially eliminate the seafood diet later.

In our survey, no statistical differences were found between IBS patients and controls in anxiety and depression scores. However, in the subgroup analysis, female patients had obviously higher score in anxiety score, which is similar to a recent study from Pakistan [3]. Studies have shown that, compared to healthy controls, 40%–60% of IBS patients with obvious mental abnormalities and early relieving mental disorders might be useful for an effective management of IBS [10, 26]. Psychosocial factors can lead to dysfunction of the brain-gut axis, which in turn causes dysfunction of the gut through neural, neuroimmune, and neuroendocrine pathways [27].

To date, no study has been conducted to explore the association between IBS and sleep disorder in medical students in China. From our data, the total score of the PSQI was significantly higher for medical students with IBS than for those without IBS, and the prevalence of severe sleep disorder was 35.5% in IBS group. Sleep disorder was independently associated with IBS. A study from China found that 34.3% of the middle school students had sleep problems, and poor sleep was independently associated with IBS [8]. It has been demonstrated that poor sleep is a dangerous stress factor, which can seriously influence the cognition, emotion, somatic reaction, and gastrointestinal function [28]. A population-based study showed that sleep disorder was associated with increased odds for multiple gastrointestinal symptoms [29]. Studies have shown that poor sleep can change the intestinal sensitivity, which increases the patient’s perception of clinical symptoms [29, 30]. Disruption of the normal biological rhythm may lead to alteration in visceral motility and sensitivity, thus changing the colonic physiological function of the gut.

Epidemiologic studies have found an increased prevalence of EALs in IBS patients [14, 31].

In our study, we have shown that the score of emotional neglect was much higher in IBS patients.

It is the first research using the CTQ questionnaire to investigate the relationships between EALs and IBS in medical students. In USA, more than 60% adults reported that they had at least one EAL before the age of 18 [32]. EALs may cause the disturbance of central nerve system including hypothalamic-pituitary-adrenal (HPA) axis, cognitive behavior, autonomic responsiveness, and emotional regulation, thus participating in the occurrence and development of IBS [14]. The other 4 subscales and the total score of CTQ were also higher in IBS group, but there were no significant differences. We speculate that, with expansion of the sample size, the result may be different.

In the present study, SLSI scores were significantly increased in patients with IBS and this phenomenon is more pronounced in women. However, there were no statistical differences in males. To our knowledge, this was the first investigation using the SLSI to assess the relationships between stress factors and IBS in medical students. In recent years, increasing evidence supports the role of stress in the pathophysiology of IBS [13, 15]. The effects of stress on functions of gut are universal, and the major effects of stress on gastrointestinal tract include alteration in gastrointestinal motility and visceral perception, increase in intestinal permeability, changes in intestinal endocrine, negative effect of intestinal mucosal blood flow, and negative effects on intestinal microbiota [13]. Differences in the following factors between women and men may explain why our findings were not the same in gender about the SLSI scores: hormone level, social role and health care seeking behavior, and physiological and psychological reactions together with coping styles when exposed to stressors.

The strength of this research was the high questionnaire responses and enough sample size to ensure the credibility of our findings. Also, we have some limitations. First, the survey was restricted to medical students, which might influence the generalizability of our results. Second, the study was based on self-reporting questionnaires, without using gastrointestinal endoscopy to exclude structural intestinal diseases; sometimes, it is unpractical in a cross-sectional survey with a large sample.

5. Conclusion

We conclude from this cross-sectional study that the prevalence of IBS in medical students is 33.3%, the scores of CTQ and SLSI were also higher in IBS patients, and sex and sleep disorder were independently associated with IBS. It may provide valuable suggestions for the necessary intervention and treatment measures towards medical students; too much attention was given just to the intestinal symptoms formerly. Further prospective studies evaluating the definite pathological mechanisms should be carried out.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Authors’ Contribution

Yang Liu and Liang Liu contributed equally to this study.

Acknowledgments

This study was supported by the National Ministry of Science and Technology “twelfth five-year” supporting project of China (no. 2014BAI08B02) and the National Natural Science Foundation of China (NSFC) (no. 81070299).

References

L. Liu, Q. F. Xiao, Y. L. Zhang, and S. K. Yao, “A cross-sectional study of irritable bowel syndrome in nurses in China: prevalence and associated psychological and lifestyle factors,” Journal of Zhejiang University Science B, vol. 15, no. 6, pp. 590–597, 2014.

M. D. Gulewitsch, P. Enck, J. Schwille-Kiuntke, K. Weimer, and A. A. Schlarb, “Mental strain and chronic stress among university students with symptoms of irritable bowel syndrome,” Gastroenterology Research and Practice, vol. 2013, Article ID 206574, 8 pages, 2013.

S. S. Naeem, E. U. Siddiqui, A. N. Kazi, A. A. Memon, S. T. Khan, and B. Ahmed, “Prevalence and factors associated with irritable bowel syndrome among medical students of Karachi, Pakistan: a cross-sectional study,” BMC Research Notes, vol. 5, article no. 255, 2012.

N. K. R. Ibrahim, W. F. Battarjee, and S. A. Almehmadi, “Prevalence and predictors of irritable bowel syndrome among medical students and interns in King Abdulaziz University, Jeddah,” The Libyan Journal of Medicine, vol. 8, p. 21287, 2013.

H. J. Jung, M. I. Park, W. Moon et al., “Are food constituents relevant to the irritable bowel syndrome in young adults? A Rome III based prevalence study of the Korean Medical Students,” Journal of Neurogastroenterology and Motility, vol. 17, no. 3, pp. 294–299, 2011.

D. A. Drossman, “The functional gastrointestinal disorders and the Rome III process,” Gastroenterology, vol. 130, no. 5, pp. 1377–1390, 2006.

S. J. Anbardan, N. E. Daryani, S.-M. Fereshtehnejad, S. T. T. Vakili, M. R. Keramati, and H. Ajdarkosh, “Gender role in irritable bowel syndrome: a comparison of irritable bowel syndrome module (ROME III) between male and female patients,” Journal of Neurogastroenterology and Motility, vol. 18, no. 1, pp. 70–77, 2012.

H.-Q. Zhou, M. Yao, G.-Y. Chen, X.-D. Ding, Y.-P. Chen, and D.-G. Li, “Functional gastrointestinal disorders among adolescents with poor sleep: a school-based study in Shanghai, China,” Sleep and Breathing, vol. 16, no. 4, pp. 1211–1218, 2012.

X. Zhu, W. Chen, and Y. Shen, “A Cross-sectional study of risk factors for irritable bowel syndrome in children 8–13 years of age in Suzhou, China,” Gastroenterology Research and Practice, vol. 2014, Article ID 198461, 6 pages, 2014.

M.-J. Modabbernia, F. Mansour-Ghanaei, A. Imani et al., “Anxiety-depressive disorders among irritable bowel syndrome patients in Guilan, Iran,” BMC Research Notes, vol. 5, article 112, 2012.

Y. Ringel, W. E. Whitehead, B. B. Toner et al., “Sexual and physical abuse are not associated with rectal hypersensitivity in patients with irritable bowel syndrome,” Gut, vol. 53, no. 6, pp. 838–842, 2004.

I. Posserud, P. Agerforz, R. Ekman, E. S. Björnsson, H. Abrahamsson, and M. Simrén, “Altered visceral perceptual and neuroendocrine response in patients with irritable bowel syndrome during mental stress,” Gut, vol. 53, no. 8, pp. 1102–1108, 2004.

P. C. Konturek, T. Brzozowski, and S. J. Konturek, “Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options,” Journal of Physiology and Pharmacology, vol. 62, no. 6, pp. 591–599, 2011.

E. J. Videlock, M. Adeyemo, A. Licudine et al., “Childhood trauma is associated with hypothalamic-pituitary-adrenal axis responsiveness in irritable bowel syndrome,” Gastroenterology, vol. 137, no. 6, pp. 1954–1962, 2009.

L. Chang, “The role of stress on physiologic responses and clinical symptoms in irritable bowel syndrome,” Gastroenterology, vol. 140, no. 3, pp. 761.e5–765.e5, 2011.

L. Shen, H. Kong, and X. Hou, “Prevalence of irritable bowel syndrome and its relationship with psychological stress status in Chinese university students,” Journal of Gastroenterology and Hepatology, vol. 24, no. 12, pp. 1885–1890, 2009.

Y.-Y. Dong, X.-L. Zuo, C.-Q. Li, Y.-B. Yu, Q.-J. Zhao, and Y.-Q. Li, “Prevalence of irritable bowel syndrome in Chinese college and university students assessed using Rome III criteria,” World Journal of Gastroenterology, vol. 16, no. 33, pp. 4221–4226, 2010.

Y.-Y. Dong, F.-X. Chen, Y.-B. Yu et al., “A school-based study with Rome III criteria on the prevalence of functional gastrointestinal disorders in Chinese College and University Students,” PLoS ONE, vol. 8, no. 1, Article ID e54183, 2013.

C. Y. Francis, J. Morris, and P. J. Whorwell, “The irritable bowel severity scoring system: a simple method of monitoring irritable bowel syndrome and its progress,” Alimentary Pharmacology and Therapeutics, vol. 11, no. 2, pp. 395–402, 1997.

P. Singh, A. Agnihotri, M. K. Pathak et al., “Psychiatric, somatic and other functional gastrointestinal disorders in patients with irritable bowel syndrome at a tertiary care center,” Journal of Neurogastroenterology and Motility, vol. 18, no. 3, pp. 324–331, 2012.

D. J. Buysse, C. F. Reynolds III, T. H. Monk, S. R. Berman, and D. J. Kupfer, “The pittsburgh sleep quality index: a new instrument for psychiatric practice and research,” Psychiatry Research, vol. 28, no. 2, pp. 193–213, 1989.

D. P. Bernstein, L. Fink, L. Handelsman et al., “Initial reliability and validity of a new retrospective measure of child abuse and neglect,” American Journal of Psychiatry, vol. 151, no. 8, pp. 1132–1136, 1994.

S. C. Paivio and K. M. Cramer, “Factor structure and reliability of the childhood trauma questionnaire in a Canadian undergraduate student sample,” Child Abuse and Neglect, vol. 28, no. 8, pp. 889–904, 2004.

B. M. Gadzella, “Three stress groups on their stressors and reactions to stressors in five studies,” Psychological Reports, vol. 94, no. 2, pp. 562–564, 2004.

S. Fukudo, “Sex and gender in irritable bowel syndrome,” Journal of Gastroenterology, vol. 41, no. 6, pp. 608–610, 2006.

A. S. Butt, M. Salih, W. Jafri, J. Yakoob, M. Wasay, and S. Hamid, “Irritable bowel syndrome and psychiatric disorders in Pakistan: a case control study,” Gastroenterology Research and Practice, vol. 2012, Article ID 291452, 6 pages, 2012.

R. S. Choung, G. R. Locke, A. R. Zinsmeister, C. D. Schleck, and N. J. Talley, “Psychosocial distress and somatic symptoms in community subjects with irritable bowel syndrome: a psychological component is the rule psychosocial distress and somatic symptoms in patients with IBS,” The American Journal of Gastroenterology, vol. 104, no. 7, pp. 1772–1779, 2009.

T. Roehrs, M. Hyde, B. Blaisdell, M. Greenwald, and T. Roth, “Sleep loss and REM sleep loss are hyperalgesic,” Sleep, vol. 29, no. 2, pp. 145–151, 2006.

F. Cremonini, M. Camilleri, A. R. Zinsmeister, L. M. Herrick, T. Beebe, and N. J. Talley, “Sleep disturbances are linked to both upper and lower gastrointestinal symptoms in the general population,” Neurogastroenterology and Motility, vol. 21, no. 2, pp. 128–135, 2009.

W. C. Orr and C. L. Chen, “Sleep and the gastrointestinal tract,” Neurologic Clinics, vol. 23, no. 4, pp. 1007–1024, 2005.

D. K. Chitkara, M. A. L. van Tilburg, N. Blois-Martin, and W. E. Whitehead, “Early life risk factors that contribute to irritable bowel syndrome in adults: a systematic review,” The American Journal of Gastroenterology, vol. 103, no. 3, pp. 765–774, 2008.

S. R. Dube, V. J. Felitti, M. Dong, W. H. Giles, and R. F. Anda, “The impact of adverse childhood experiences on health problems: evidence from four birth cohorts dating back to 1900,” Preventive Medicine, vol. 37, no. 3, pp. 268–277, 2003.