Glucocorticoid Dose Thresholds Associated With All-Cause and Cardiovascular Mortality in Rheumatoid Arthritis

Objective. To delineate daily and cumulative glucocorticoid dose thresholds associated with increased mortality rates in rheumatoid arthritis (RA). Methods. We studied RA patients recruited from rheumatology clinics. Annually, we assessed the glucocorticoid dose, demographic, socioeconomic, clinical, and laboratory features of RA, cardiovascular (CV) risk factors, and vital status. We used Cox proportional hazards regression to assess associations between the daily or cumulative glucocorticoid dose and death, adjusting for potential confounders and for the propensity to receive glucocorticoids. We tested strata of the glucocorticoid dose to delineate the threshold associated with death. Results. We studied 779 RA patients with a total of 7,203 person-years of observation, during which 237 of them died, yielding a mortality rate of 3.2 per 100 person-years (95% confidence interval [95% CI] 2.8-3.7). One hundred twenty of the deaths were due to CV causes, yielding a CV mortality rate of 1.8 (95% CI 1.5-2.1). Exposure to glucocorticoids was associated with a dose-dependent increase in death from all causes, with a ratio (HR) of 1.07 per mg of prednisone per day (95% CI 1.05-1.08). Compared to patients who were not receiving corticosteroids, the minimum daily prednisone dose threshold associated with an increase in all-cause mortality was 8-15 mg, with an adjusted HR of 1.78 (95% CI 1.22-2.60). For the cumulative dose of gluco-corticoids, the minimum dosage associated with allcause mortality was 40 gm (HR 1.74 [95% CI 1.25-2.44]). Conclusion. Glucocorticoid use in RA is associated with a dose-dependent increase in mortality rates, with a daily threshold dose of 8 mg, at which the number of deaths increased in a dose-dependent manner. These findings may assist clinicians in selecting the appropriate glucocorticoid dosage for RA patients who require these agents.