Purpose: 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.
Methods: 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 3 years, were followed-up until institutionalization, death, or 31 December 2007. Reinitiation rates after ≥180 days 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 10 years.
Results: 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 180 days by the end of the follow-up period. Of the discontinuers, 46.7% restarted the treatment within 1 year and 88.7% by the end of the follow-up. Of those followed up for ≥10 years, 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 10 years.
Conclusion: 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.