Multiple sclerosis and inflammatory bowel diseases: a systematic review and meta-analysis.

The association between multiple sclerosis (MS) and inflammatory bowel disease (IBD) has been suggested, apart from their common epidemiological and immunological patterns, also due to observations of increased incidence of both IBD among MS patients and MS among IBD patients. We estimated the risk of concurrent IBD and MS comorbidity, using data from all available case-control studies. We calculated the corresponding Risk ratios (RRs) in each included case-control study to express the risk of IBD and MS concurrence at a given population. We performed additional subgroup analyses according to the type of registry from which the data of the cases were exported (IBD or MS registry) and the IBD type (Crohn's disease, CD or Ulcerative colitis, UC). We included 10 studies, comprising a total of 1,086,430 patients (0.08% of them with concurrent IBD and MS). Pooled RR for IBD/MS comorbitity was 1.54 (95% CI 1.40-1.67; p < 0.0001) with no differences (p = 0.91) among IBD and MS registries (RR 1.53, 95% CI 1.36-1.72, p < 0.001 for MS comorbidity in IBD patients vs. RR 1.55, 95% CI 1.32-1.81, p < 0.001 for IBD comorbidity in MS patients). No difference was also found on the risk of MS comorbidity among patients with CD or UC (RR 1.52, 95% CI 1.34-1.72, p < 0.001 vs. RR 1.55, 95% CI 1.38-1.74, p < 0.001; p for subgroup differences: 0.84). In all analyses no evidence of heterogeneity or publication bias was detected. Both IBD and MS patients seem to have a fifty-percent increased risk of MS or IBD comorbidity, respectively, with no apparent differences between patients with CD or UC.