Confounding by Indication Probably Distorts the Relationship between Steroid Use and Cardiovascular Disease in Rheumatoid Arthritis: Results from a Prospective Cohort Study

Objective To evaluate the risk of cardiovascular disease in patients with rheumatoid arthritis exposed to glucocorticoids. Methods Retrospective analysis of exposure to glucocorticoids in a prospective cohort of 353 patients with rheumatoid arthritis followed from June 2001 up to November 2011 for incident cardiovascular disease in a hospital-based outpatient cohort in the Netherlands. Hazard ratios with 95%-confidence intervals were calculated for the association between different types of exposure to glucocorticoids and incident cardiovascular disease. Associations were adjusted for demographics, cardiovascular risk factors and disease related parameters. Results Recent and current exposure to glucocorticoids were associated with incident cardiovascular disease, as was a longer duration of exposure and cumulative exposure to glucocorticoids. Adjustment for disease activity and severity negated the association. Conclusion In observational studies the finding of incident cardiovascular disease in patients with rheumatoid arthritis exposed to glucocorticoids is strongly confounded by indication due to high disease activity. The adverse cardiovascular effects of glucocorticoids might be balanced by positive effects working through inflammation control.