Effects of the use of phytosterol/-stanol-enriched margarines on adherence to statin therapy.

Purpose: The use of margarines enriched with phytosterols or phytostanols is recommended as an appropriate adjunctive therapy for patients with certain lipid profiles, but may result in a behavioral modification leading to a change in person's adherence to lipid-lowering drug treatment. This study aimed to examine the influence of the use of margarines enriched with phytosterols/-stanols on adherence to statin therapy.

Methods: Retrospective data from food frequency questionnaires were used to assess phytosterol/-stanol-enriched margarine intake from a population based, longitudinal cohort between 1998 and 2007. Intake data were linked to pharmacy-dispensing records. Multivariate Cox proportional-hazards models were used to calculate hazard ratios for discontinuation of statin therapy. Drug-taking compliance was compared between users and non-users of enriched margarine using the Mann-Whitney U-test. Pre-defined subgroup analyses were performed to evaluate differences in adherence between prevalent statin users and starters of statins.

Results: Among 4848 subjects, 522 used statins only and 60 combined these drugs with phytosterol/-stanol-enriched margarine. Overall statin discontinuation rates were not significantly different between the users and non-users of enriched margarine, but more combination users discontinued statin therapy within 12 months in the subgroup of starters (HR(adj) : 2.52 [95%CI: 1.06-6.00]). Drug-taking compliance was high in both users and non-users of enriched margarine and was slightly lower in combination users (P<0.10).

Conclusions: These results imply that persons who combine enriched margarines with statins may neglect taking their drug according to the prescription. Further investigations in larger populations are important, especially among patients susceptible to a low adherence to drug therapy.