Rheumatoid Arthritis and Its Implications on Inflammatory Bowel Disease.

Background: The association between inflammatory bowel disease (IBD) and arthritis has long been known, but it was not until the 1950s that IBD-associated arthritis was recognized as a distinct pathology independent from rheumatoid arthritis (RA). There is evidence that RA and other autoimmune conditions exist at higher rates in patients with IBD compared to the general population. We aimed to determine if the presence of RA in IBD patients is a factor for mortality and IBD-related surgery in this population.

Methods: Using Epic's Slicer Dicer function, we queried the International Classification of Diseases, 10th Revision (ICD-10) codes K50 and K51 to identify patients with IBD. Duplicates and those with incomplete information were excluded, leaving a total of 3,613 patients. Data collected included basic demographic information, surgical history, and the presence of RA. We used Student's -test to analyze between group differences for the continuous variables. When it was determined that variances for the comparisons of continuous data were unequal, Welch-Satterthwaite -test statistics were used. We used the Chi-square test to analyze between group differences for the categorical variables. The Fisher's exact test was employed when any of the expected frequencies was 5 or less. All tests were two-sided with criterion for statistical significance at a P value less than 0.05. All the analyses were done by SAS 9.4 (SAS Institute, Cary, NC).

Results: Of the approximately 2.7 million adults in Slicer Dicer, there were 3,613 patients (0.13%) identified with IBD. Patients with ulcerative colitis (UC) accounted for 37% of the total group (n = 1,343) and 2,270 patients (62.8%) had Crohn's disease (CD). From the total, 2,084 were women (57.68%) and 1,529 (42.32%) were men. More than 90% of the patients were white (n = 3,321). The mean age was 53.3 ± 18.5. Eight hundred forty-eight patients (23.47%) had documented RA. Mortality was higher in patients with IBD and RA than those with IBD alone (7.31% vs. 3.98%, P value ≤ 0.0001).

Conclusions: IBD patients with RA have higher mortality rates and need for IBD-related surgery than patients with IBD alone.