Estimation of optimal adherence threshold for tumor necrosis factor inhibitors in rheumatoid arthritis.

Increased PDC was associated with a decreased risk of adverse outcomes, except ER visits. The optimal PDC for TNF inhibitors in Medicare patients with RA based on clinical outcomes was about 60%. Key Points • The optimal proportion of days covered threshold for tumor necrosis factor inhibitors at 365 days based on clinical outcomes was found to be about 60%, which is lower than the traditional 80% used to define adherence. • Increased adherence was associated with decreased risks of oral glucocorticoid use, hospitalization, and the composite outcome. However, it was also associated with an increased risk of emergency room visits. • The mean time-varying 90-day proportion of days covered decreased throughout the study starting 92% at day 1 of follow-up to 62% at day 365.