Dynamics of long-term statin therapy

Abstract

Knowledge of the different usage patterns that emerge during a long-term statin therapy is limited. The aim of this study was to characterize statin use, including the rates of reinitiation after extended periods of non-use, transitions between good and poor adherence, and the effect of the length of a drug-free period on the identification of new users. The study cohort comprised individuals aged 45-84 years who were identified in the Finnish prescription register as having purchased statins between 1997 and 2007. New users in 1997, including those with no statin purchases during the preceding 3years, were followed-up until institutionalization, death, or 31 December 2007. Reinitiation rates after ≥180days with no refill for statins were analyzed using survival analysis. Annual adherence levels and the prevalences of good (proportion of days covered ≥0.80) and poor (<0.80) adherence were calculated for ten 1-year periods following initiation. For statin users in 2007, purchases were captured over the previous 10years. Based on the data extracted from the Finnish prescription register, 32,760 persons initiated statin treatment in 1997, of whom 48.1% had discontinued it for at least 180days by the end of the follow-up period. Of the discontinuers, 46.7% restarted the treatment within 1year and 88.7% by the end of the follow-up. Of those followed up for ≥10years, 51.8% had ≥6 years of treatment with good adherence. In 2007, 27.7% of the initiators having no statin purchases within the previous year had refills during the preceding 10years. Statin use is dynamic. This should be taken into consideration in clinical practice and when studying the incidence, patterns, and health outcomes of statin use.