Comorbidities as risk factors for rheumatoid arthritis (RA) and their accrual after RA diagnosis

Abstract

Objective— To determine the prevalence of comorbidities in RA, discover which comorbidities might predispose to developing RA, and identify which comorbidities are more likely to develop after RA. Patients and Methods— We performed a case-control study using a single-center biobank, identifying 821 cases of RA (143 incident RA) between January 1 2009 and February 28 2018, defined as two diagnosis codes plus a disease-modifying antirheumatic drug. We matched each case to three controls based on age and sex. Participants self-reported presence and onset of 74 comorbidities. Logistic regression models adjusted for race, body mass index (BMI), education, smoking, and Charlson comorbidity index. Results— After adjustment for confounders and multiple comparisons, eleven comorbidities were associated with RA, including epilepsy (OR 2.13, p=.009), obstructive sleep apnea (OSA) (OR 1.49, p=.001), and pulmonary fibrosis (OR 4.63, p<.001), but cancer was not. Inflammatory bowel disease (IBD) (OR 3.82, p<.001), type 1 diabetes (OR 3.07, p=.01), and venous thromboembolism (VTE) (OR 1.80, p<.001), occurred more often before RA diagnosis compared to controls. In contrast, myocardial infarction (OR 3.09, p<.001) and VTE (OR 1.84, p<.001) occurred more often after RA diagnosis compared to controls. Analyses restricted to incident RA cases and their matched controls mirrored these results. Conclusion— IBD, type 1 diabetes, and VTE might predispose to RA development, while cardiovascular disease, VTE, and OSA may result from RA. These findings have important implications for RA pathogenesis, early detection, and recommended screening.