Irritable bowel syndrome and antidepressants.

In this issue of JMCP, Faresjö and colleagues found that 13.3% of patients with irritable bowel syndrome (IBS) reported using antidepressants versus 4.5% of control patients without IBS.1 The more than 3-fold higher use of antidepressants (odds ratio [OR] = 3.27, 95% confidence interval [CI] = 2.27-4.70) among patients with IBS is not a surprising finding, but the actual use of drugs by IBS patients is little studied despite the high prevalence of IBS, which is estimated to affect 12% of adults in the United States.2 However, a plethora of research reports exist regarding the comorbidity of psychiatric conditions and IBS; a MEDLINE search performed in October 2008 revealed 456 citations for the combination of the search terms “irritable bowel syndrome” and “depression.” The medical literature shows a strong relationship of IBS with anxiety, chronic fatigue syndrome, and fibromyalgia, as well as depression.3,4 The research is sufficiently specific to differentiate a higher frequency of IBS symptoms with panic disorder, generalized anxiety disorder, and major depressive disorder versus social anxiety disorder, specific phobia, and obsessivecompulsive disorder.5 There is considerable discussion regarding the role of serotonin in IBS,6 which suggests that some antidepressants may be more effective than others. Hayee and Forgacs in their clinical review (2007) presented evidence that (a) the diagnosis of IBS is stigmatized by the method of exclusion, leading to an aura of negativity for the patient; (b) IBS does not have a single cause and is associated with a complex of symptoms; (c) the association of IBS with psychiatric disorders begs the question of cause and effect; (d) despite the reported high prevalence of IBS, many more patients may have IBS who do not consult a physician; and (e) among the antidepressant drugs, the tricyclic antidepressants have been studied most often in IBS, with consistently favorable effects and a number needed to treat (NNT) of 3.2 (95% CI = 2.16.5) compared with an NNT of 2.0 for cognitive behavioral therapy and mixed but generally poor results with the selective serotonin-reuptake inhibitors (SSRIs).7 Unfortunately, in the present study, Faresjö et al. did not record the subtypes of antidepressants (e.g., SSRIs, serotonin–norepinephrine reuptake inhibitors, or tricyclic antidepressants) reported by the respondents in their population survey.