More than 10% of patients developed irritable bowel syndrome (IBS) within a year after infectious enteritis, which gave them a more than fourfold greater risk than that of controls, according to a systematic review and meta-analysis of 45 studies.
“Protozoal and bacterial enteritis confer the greatest overall risk, although the magnitude of increased risk diminishes with time since exposure,” Fabiane B. Klem, MD, and Akhilesh Wadhwa, MD, of Mayo Clinic in Rochester, Minn., and their associates wrote in the April issue of Gastroenterology. Other significant risk factors for postinfectious IBS (PI-IBS) included female sex, clinically severe infections, antibiotic therapy, and comorbid psychological distress, they said.
Postinfectious IBS can last at least a decade after resolution of campylobacteriosis, shigellosis, salmonellosis, giardiasis, and norovirus infections, even when patients have no other risk factors for IBS, the researchers noted. To update and expand the most recent meta-analysis of this topic ( Aliment Pharmacol Ther. 2007;26:535-44 ), the investigators searched Ovid Medline, EMBASE, Web of Science, and Cochrane Database of Systematic Reviews for studies published from 2006 through Aug. 31, 2015. This search yielded 45 studies, including 30 studies comparing infected patients with controls, who were usually matched by age, sex, and geographic location (Gastroenterology. 2017 Jan 6. doi: 10.1053/j.gastro.2016.12.039 ).
In all, 10.1% of patients with infectious enteritis developed IBS in the next 12 months (95% confidence interval, 7.2-14.1) – a 4.2-fold increase in risk, compared with that of controls (risk ratio, 4.2; 95% CI, 3.2-5.7). This risk subsequently dropped, but remained significantly elevated (RR, 2.3; 95% CI, 1.8-3.0), compared with controls. “Of patients with enteritis caused by protozoa or parasites, 41.9% developed IBS; of patients with enteritis caused by bacterial infection, 13.8% developed IBS,” the researchers emphasized. Patients with these infections remained at elevated risk of PI-IBS even after 1 year. Viral enteritis also significantly increased the risk of PI-IBS, but risk dropped to baseline levels after a year.
Among 10 pooled studies of IBS subtypes, 46% of patients had mixed IBS, 39% had diarrhea-predominant IBS, and 15% had constipation-predominant IBS. Female sex doubled the odds of PI-IBS (odds ratio, 2.2; 95% CI, 1.6-3.1) in 11 pooled studies. Significant clinical risk factors for PI-IBS included diarrhea lasting more than 7 days (eight studies; OR, 2.6; 95% CI, 1.5-4.6), bloody stool (four studies; OR, 1.9; 95% CI, 1.1-3.0), and antibiotic therapy during infectious enteritis (seven studies; OR, 1.7; 95% CI, 1.2-2.4).
Multiple reports linked PI-IBS to clinical psychological distress at the time of infectious enteritis. Specific risk factors included depression based on the Hospitalization Anxiety and Depression Scale (five studies; OR, 1.5; 95% CI, 1.2-1.9), anxiety based on the Hospital Anxiety and Depression Scale (four studies; OR, 2.0; 95% CI, 1.3-2.9), somatization (four studies; OR, 4.1; 95% CI, 2.7-6.0), and neuroticism (two studies; OR, 3.3; 95% CI, 1.6-6.6). Isolated studies also implicated hypochondriasis, extroversion, negative illness beliefs, stress, sleep disturbance, and adverse life events in the preceding year, the researchers said.
They found no evidence of publication bias, but noted a substantial amount of heterogeneity among studies. Also, some studies did not report multivariate analyses, so individual odds ratios might reflect “a conglomeration of factors,” they said.
The National Institutes of Health and the American Gastroenterological Association funded the work. The investigators reported having no conflicts of interest.