Aims: To determine the patterns and predictors of long-term adherence to statin therapy in all patients with diabetes in the community setting.
Methods: We retrospectively studied patients with diabetes who were resident in Tayside, Scotland from 1 January 1989 to 31 May 2003 and initiated statin treatment during that time. The main outcome measure was percentage of days covered (PDC) by a statin, calculated at regular intervals. Predictors of suboptimal adherence (PDC < 80%) were identified using generalized linear models for repeated measures.
Results: Six thousand four hundred and sixty-two patients were included in the study. In the first year, the mean PDC was 87, 61% in the first and second quarter, respectively, and 65% after 13 years. Less than 50% of patients maintained a PDC of > 80% after 13 years. Predictors of poor long-term adherence were younger age, higher HbA(1c), no history of smoking, no cardiovascular morbidity at baseline and occurrence of cardiovascular disease after statin commencement.
Conclusions: This study suggests that barriers to long-term adherence to statins tend to arise early on in the therapeutic course. In general, long-term adherence is poor in patients with diabetes, especially among those with few other cardiovascular risk factors.