Biologic therapy is associated with malignancies among Israeli patients with rheumatoid arthritis: A population‐based study

Abstract Aims To examine whether biologic disease‐modifying anti‐rheumatic drugs (bDMARDs) are associated with increased risk of malignancy among Israeli patients with rheumatoid arthritis (RA). Methods We identified RA patients meeting specified inclusion and exclusion criteria from the Leumit healthcare services database between the years 2000 and 2017. Data were collected regarding bDMARD and conventional DMARD consumption, types of malignancies, and their temporal relation to RA diagnosis. The association between baseline variables and occurrence of malignancies was examined by Cox regression. Results Among 4268 eligible RA patients, 688 (16.12%) were diagnosed with any malignancy. Melanoma skin cancer (MSC) was the most prevalent malignancy (148/688, 21.5%). The proportions out of all malignancies of MSC and non‐melanoma skin cancer (NMSC) were higher after than before RA diagnosis (24.7% vs 19.1%, p = .025 and 24.7% vs 13.0%, p = .021, respectively). A higher proportion of RA patients diagnosed with malignancy used bDMARDs in comparison with RA patients who were malignancy‐free (40.2% vs 17.5%, p < .001). After adjusting for demographic and clinical variables, bDMARDs were associated with an increased risk of malignancy (hazard ratio 1.42, 95% confidence interval 1.10‐1.78). Conclusions Biologic DMARDs are associated with increased risk of malignancy among Israeli RA patients, presumably contributed by MSC and NMSC. MSC was the most prevalent type of malignancy in this cohort and may indicate a predisposition state among Israeli RA patients.