There is a concern that poor compliance to cholesterol lowering agents (CLA) may compromise their potential benefits. The objective of this study was to estimate compliance to CLAs, in the context of clinical practice in Quebec.

This study was performed using data from the Régie de l'Assurance Maladie du Québec Persistence and adherence to treatment were estimated separately. An index combining these 2 measures was also calculated.

In a random sample of patients (n = 428304) from the Régie de l'Assurance Maladie du Québec administrative database, 14076 were new users of a CLA. After 24 months, the persistence rate with the statins was significantly higher than with other CLAs (83% vs 69%; P < .001). The proportion of patients who switched from their initial statin varied across the statins (ranging from 7% to 34%). The proportion of patients who were 80% adherent to their treatment was significantly lower with the other CLA than with statins (43% vs 60%, P < .001). A composite index combining monthly persistence and adherence was calculated. This index was significantly higher for atorvastatin than for the other CLAs (P < .001) and the other statins (P < .01), with the exception of simvastatin (P = .09).

Over a 2-year period, a large proportion of patients using a statin remained persistent to treatment. The overall rate of compliance (persistence and adherence) after 2 years was >60% with some statins.