Statin adherence and treatment LDL-cholesterol response in type 2 diabetes patients

Background: In clinical practice statins are not optimally used and lipid targets are not achieved in at least a third of the patients. This lack of treatment response could be due to undertreatment (low-dose statin) and low adherence to treatment. Objectives: To determine the relationship between statin dose, adherence and LDL-cholesterol response in new statin users. Methods: This cohort study was performed using data from the Groningen Initiative to Analyse Type 2 Diabetes Treatment (GIANTT) database. The relation between adherence and LDL-cholesterol response was assessed during the first year of treatment with a standard-dose statin using linear regression, adjusting for covariates. The modifying effect of low-dose versus standard-dose was assessed in a propensity-score matched cohort. Adherence was measured as the medication possession ratio (MPR). Results: In total 22% of the 8,282 new statin users started on a low-dose, around 80% of them stayed on this low-dose during the first year of treatment. These patients did not differ in LDL-cholesterol level and macro- and microvascular comorbidity compared to patients on standard-dose treatment. The mean adherence was around 80%in both groups. The effect of adherence on LDL-cholesterol response, measured in 1,797 patients, was dependent on the baseline LDL-cholesterol level. With an average baseline LDL-cholesterol level of 3.8mmol/l, an increase in adherence of 10% resulted in an estimated decrease in LDL-cholesterol of 0.2mmol/l. In the matched sample of 950 patients, treatment dose modified the association between adherence and LDL outcome. For adherence rates >80% there was a significant difference in effectiveness of low-dose versus standard-dose statin treatment. Conclusions: For patients with poor adherence rates (MPR