Refill adherence and persistence to lipid-lowering medicines in patients with type 2 diabetes: A nation-wide register-based study

Abstract

Purpose: This study aimed to describe and compare refill adherence and persistence to lipid-lowering medicines in patients with type 2 diabetes by previous cardiovascular disease (CVD). Methods: We followed 97 595 patients (58% men; 23% with previous CVD) who were 18 years of age or older when initiating lipid-lowering medicines in 2007–2010 until first fill of multi-dose dispensed medicines, death, or 3 years. Using personal identity numbers, we linked individuals' data from the Swedish Prescribed Drug Register, the Swedish National Diabetes Register, the National Patient Register, the Cause of Death Register, and the Longitudinal Integration Database for Health Insurance and Labour Market Studies. We assessed refill adherence using the medication possession ratio (MPR) and the maximum gap method, and measured persistence from initiation to discontinuation of treatment or until 3 years after initiation. We analyzed differences in refill adherence and persistence by previous CVD in multiple regression models, adjusted for socioeconomic status, concurrent medicines, and clinical characteristics. Results: The mean age of the study population was 64 years, 80% were born in Sweden, and 56% filled prescriptions for diabetes medicines. Mean MPR was 71%, 39% were adherent according to the maximum gap method, and mean persistence was 758 days. Patients with previous CVD showed higher MPR (3%) and lower risk for discontinuing treatment (12%) compared with patients without previous CVD (P < 0.0001). Conclusions: Patients with previous CVD were more likely to be adherent to treatment and had lower risk for discontinuation compared with patients without previous CVD.