Original articles
Review article
Somatic comorbidities of irritable bowel syndrome: A systematic analysis

https://doi.org/10.1016/j.jpsychores.2008.02.021Get rights and content

Abstract

Objective

A large number of irritable bowel syndrome (IBS) patients are additionally afflicted with other somatic intestinal and/or extraintestinal comorbidities. The occurrence of one or more comorbidities is correlated with enhanced medical help seeking, worse prognosis, and higher rates of anxiety and depression—all resulting in a reduced quality of life. The aims of this study were, firstly, to review the literature on comorbidities of IBS and to assess gastrointestinal and extraintestinal comorbidities, and, secondly, to evaluate explanatory hypotheses and possible common pathophysiological mechanisms.

Methods

We systematically reviewed the scientific literature in the past 25 years, as cited in MEDLINE.

Results

IBS patients present with a twofold increase in somatic comorbidities compared to controls, possibly caused by common pathophysiological mechanisms. Nevertheless, to date, there has been no convincing evidence for a consolidated underlying pathophysiology or somatization.

Gastrointestinal disorders, such as functional dyspepsia, gastroesophageal reflux disease, functional constipation, and anal incontinence, occur in almost half of the patients. In a broad variety of extraintestinal comorbidities, fibromyalgia, chronic fatigue syndrome, and chronic pelvic pain are best documented and appear in up to 65%.

Conclusion

The knowledge and structured assessment of comorbid somatic symptoms might allow to identify subgroups of IBS patients with special characteristics and lead to adaptation of the therapeutic concept.

Introduction

In irritable bowel syndrome (IBS) patients, somatic (intestinal and extraintestinal) comorbidities, particularly extraintestinal symptoms, are present twice as much as in controls [1]. The appearance of comorbidities in patients with IBS is associated with reduction in quality of life [1] and increased health care seeking, with a consecutive rise in costs. More than 65% of the expenses incurred by IBS patients can be attributed to extraintestinal indications [2]. Moreover, a positive correlation between the appearance of one or more IBS-related somatic comorbid conditions and the severity of IBS symptoms, as well as the occurrence of anxiety and depression, was detected [3], [4]. Vandvik et al. [5] revealed a positive correlation between the incidence of somatic comorbidities and higher levels of mood disorder, health anxiety, neuroticism, adverse life events, reduced quality of life, and increased health care seeking, compared to IBS patients without somatic comorbidities.

Various concepts explaining this phenomenon (e.g., similarities in underlying pathophysiological mechanisms such as visceral hypersensitivity and dysregulation of the autonomic nervous system) have been proposed [6].

Section snippets

Intestinal comorbidities

Besides the considerable overlap between functional gastrointestinal disorders, current data suggest that IBS patients also suffer from various intestinal comorbidities (Fig. 1).

IBS and intestinal comorbidities: key messages

A wide spectrum of diagnostic procedures is necessary to exclude other conditions when IBS is suspected to be the cause of abdominal complaints due to the broad overlap between various gastrointestinal diseases. Furthermore, in the individual patient, dominating symptoms often vary over time, making it even harder to categorize the IBS subtype according to Rome criteria, which is essential for an adequate therapeutic procedure. Besides the characterization of the leading symptoms, it is

Extraintestinal comorbidities

IBS patients, as well as patients with other functional gastrointestinal diseases, remarkably more often suffer from extraintestinal comorbidities than patients with nonfunctional gastrointestinal diseases (Fig. 2). Comparison of epidemiological studies showed a high variance of data. Among others, this can be attributed to different study conditions in primary, secondary, and tertiary care, and different definitions of diseases, as well as diverse classification of patient subgroups.

IBS and extraintestinal comorbidities: key messages

Except for BHR, there is clear evidence that the mentioned extragastrointestinal symptoms are significantly more common in IBS patients than in controls. The best-documented nonpsychiatric extraintestinal comorbidities are fibromyalgia, chronic fatigue syndrome, and chronic pelvic pain. The evidence supporting a common underlying etiology is unconvincing. Common psychological features or physiological mechanisms are possible but have not been proven yet.

The observation that IBS patients

Common pathophysiological mechanisms in IBS and somatic comorbidities

The frequency of intestinal and extraintestinal comorbidities in IBS suggests that the underlying pathophysiological mechanisms are not confined to the respective organ, but rather involve superior systems such as the autonomic nervous system and the brain–gut axis.

Regarding their clinical manifestation, obviously many similarities can be found between IBS and the most frequent somatic comorbidities (FM, chronic fatigue syndrome, chronic pelvic pain, and TMJ). In all of these diseases,

IBS patients with somatic comorbidities: subgroup or part of a global disorder?

Factor analyses proved that IBS occurs independently of FD and other functional gastrointestinal diseases [87], [88], [89]. Moreover, IBS shows a wide overlap with FM, chronic fatigue syndrome, anxiety, and depression, although the single diagnoses are autonomous. This argues against a global disease.

Furthermore, other multivariate statistical analyses also indicated that comorbidities of IBS are independent diseases [57], [90], and there is clear evidence that IBS, FM, and chronic fatigue

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