Intestinal symptoms and psychological factors jointly affect quality of life of patients with irritable bowel syndrome with diarrhea

Being specific for IBS, the IBS-QOL scale has been widely used in clinical practice [4,15-17] and has been shown suitable for evaluating the severity of IBS and assessing treatment outcomes in clinical practice [17]. The present study found that overall IBS-QOL scores were generally lower in IBS-D patients, with food avoidance scores being the lowest. This result is in accordance with the results of other studies evaluating IBS patients [3,4,8,13,17-19]. Epidemiological studies in both Asian [7,20-22] and Western [23-26] patients have shown that the prevalence of IBS was higher in females than in males. In addition, female patients were reported to have lower IBS-QOL scores than males [15,27]. In the present study, 58.6% of the patients were males, suggesting that males may be more likely to have IBS-D whereas females are more likely to have IBS-C [28,29], or that the rate of hospital visits may be higher among Chinese males than females with IBS-D. Although overall IBS-QOL scores were similar in males and females, food avoidance and social reaction scores were lower in females, similar to previous findings [3,16]. The significantly lower food avoidance scores in female IBS-D patients were due mainly to their response to the statement, “I have to watch the amount of food I eat because of my bowel problems.” This suggests that female IBS-D patients are more likely to regard a certain type of improper food as the main cause of their intestinal symptoms and want to relieve their symptoms by avoiding that type of food. In contrast, male IBS patients are reported to have different IBS-related types and quantities of food than females [30]. The social reaction scores were significantly lower for female than male IBS-D patients, as indicated by their replies to the statements: “I am embarrassed by the smell caused by my bowel problems” and “I worry that people think I exaggerate my bowel problems”, to which female patients responded more affirmatively. In addition, female IBS-D patients were more likely to regard their bowel problems as limiting the clothing they could wear (item 21) and to want to avoid strenuous activity (item 22) and long trips (item 27). All of these responses indicate that the social reactions of female IBS-D patients are affected by their intestinal symptoms. Although gender-related traits have been associated with IBS-QOL, it is unclear whether these traits or their linked psychosocial disorders affected patients’ responses to their intestinal symptoms [15].

Studies of the impact of age, type of work, occupation, education, marriage and family economic status on the QOL of IBS patients have yielded different results [7,21,31-33]. A study in Egypt showed that people with low education and income levels and those performing manual labor were more likely to suffer from IBS than educated professionals [34]. In contrast, this study found that QOL in Chinese patients with IBS-D was not affected by age, education, occupation, type of work, marriage or family economic status, consistent with findings in Iran [4].

Korean studies [3,5] showed that the overall score of intestinal symptoms and the severity described by the patient were independent factors affecting health-related QOL (HRQOL) scores of IBS patients, and that pre-defecation abdominal pain/discomfort significantly affected patients’ QOL [3,35,36]. In the present study, overall IBS-QOL scores of IBS-D patients were significantly correlated with overall scores of intestinal symptoms. Further analysis showed that the main intestinal symptoms, including the frequency and degree of pre-defecation abdominal pain/discomfort, increased numbers of bowel movements and loose/watery stools at symptom onset, and improvements in abdominal pain/discomfort following defecation, did not significantly affect the QOL of patients with IBS-D. Although no single symptom significantly affected the QOL of IBS-D patients, a significant negative correlation was observed between their main intestinal symptom scores and overall IBS-QOL scores, indicating that the integrated severity of intestinal symptom may reduce patients’ QOL.

Defecation urgency and passing mucus were the most common IBS-associated symptoms in the present study, with both being independent risk factors affecting QOL. We did not determine the mechanism by which urgency and passing mucus affected patients’ QOL. In clinical practice, patients usually state that urgency limited their travel activities, even for taking a bus to working sites. Most people in China use public transportation, with few sites on these routes having toilets. The effect of passing mucus on QOL may be related to patients’ lack of medical knowledge and paying too much attention to passing mucus. Urgency and passing mucus contributed to the decreased overall IBS-QOL score in male patients and had a greater effect on total QOL scores of male than of female IBS-D patients.

Psychological factors are also associated with the pathogenesis of IBS, since they can affect intestinal function via the autonomic nervous system and brain-gut axis [37,38]. It has been estimated that 50% to 90% of IBS patients have psychological disorders [38,39], primarily depression and anxiety, although neuroses and hypochondria have also been reported. These comorbid psychological disorders may affect patients’ QOL [3,6,13,40], and psychological treatment may improve their QOL [11,41]. Evaluation using the Hospital Anxiety and Depression Scale (HAD) showed that IBS patients with anxiety and depression often had more serious intestinal symptoms and that their QOL was compromised significantly [5,42]. However, few studies have analyzed the structural factors linking the HAD and HAMA/HAMD scales with patients’ QOL. One study found that eight factors independently predicted mental HRQOL, including feeling tense, nervous, and hopeless; difficulty sleeping; tiring easily; low sexual interest; IBS symptom interference with sexual function; and low energy [40]. Results of the present study showed that overall IBS-QOL scores correlated negatively with HAMD and HAMA scores, and that psychomotor retardation on the HAMD scale was able to predict patients’ QOL independently. This factor on the HAMD scale includes depressed mood (dysphoria), work and interests, psychomotor retardation status and sexual function (loss of libido). Depressed mood and loss of interest are core symptoms in depressive disorders. Depressed patients with psychomotor retardation may require intensive care to ensure adequate food and fluid intake and sufficient personal care. Our results indicate the need to recognize psychomotor retardation and to apply appropriate intervention to improve QOL.

HAMD scores, including scores on its structural factors anxiety/somatization, cognitive disorder, and psychomotor retardation, and HAMA scores, including scores of its two structural factors, somatic anxiety and psychic anxiety, were significantly higher in female than in male patients with IBS-D, suggest that the associated psychological disorders were more significant in female patients. Only the psychomotor retardation score, an acknowledged characteristic of depression, significantly affected patients’ QOL. However, somatic anxiety was an independent predictor of QOL in male patients.

The associations between intestinal symptoms and/or the psychological state of IBS patients and their QOL have been verified [5,6,36,43]. Psychological distress is less dependent on gastrointestinal symptom severity in patients with IBS than in those with inflammatory bowel diseases; in the latter, psychological distress has a greater direct effect on HRQOL than gastrointestinal symptoms [6]. Results of the present study showed that the intestinal symptom scores of IBS-D patients were positively correlated with HAMD/HAMA scores, but that both were negatively correlated with patients’ IBS-QOL scores, suggesting an interactive network linking intestinal symptoms, QOL, and psychological state. These findings suggest that the frequent onset or continuous presence of intestinal symptoms (represented by high intestinal symptom score) can aggravate patients’ psychological burden, and that comorbid psychological disorders may aggravate patients’ subjective feelings about their intestinal and somatic symptoms, resulting in multiple extraintestinal symptoms. This may lead patients to excessively avoid foods and disproportionately worry about their intestinal symptoms, reducing their outside activities and, in turn, their QOL. This cycle suggests that the reduced QOL in IBS-D patients results from the combined impact of intestinal symptoms and psychological abnormalities.

This study had several limitations. First, since our hospital is a referral center for patients in China with difficult and complicated diseases, most of the patients enrolled in this study had moderate to severe illness. Second, the IBS symptom questionnaire and the intestinal symptom scoring method have not been validated. Finally, the severity and frequency of intestinal and defecation-related symptoms were reported by patients themselves. However, nociceptive contributions, the degree of disability, culture, psychological distress and poor HRQOL may influence patients’ report of the severity of their symptoms [35].