Adherence and persistence with single-dosage form extended-release niacin/lovastatin compared with statins alone or...

Lipid-lowering therapies have been shown to reduce cardiovascular events and mortality; patient cooperation with therapy varies. A fixed-dose combination product, extended-release niacin/lovastatin (ERNL), has been shown to be beneficial in lipid management; however, little is known regarding patient behavior with ERNL therapy.

To evaluate patient adherence and persistence with ERNL, statin monotherapy (SM), extended-release niacin (ERN) monotherapy, and ERN plus a statin (ERN-S).

Prescription claims for lipid-lowering therapies were obtained from a pharmacy benefits manager between 2002 and 2003. Claims for a total of 2389 patients were analyzed for adherence and persistence, using medication possession ratios (MPRs) and proportions of days covered (PDCs). Adherence and persistence were defined, respectively, as an MPR or PDC greater than or equal to 0.80. Logistic regression was conducted to detect differences among groups. Covariates included age, gender, copay, and number of lipid-lowering therapies, a surrogate for disease severity.

Average MPR scores were relatively high in all groups at 0.88, 0.81, 0.89, and 0.90 for ERNL, SM, ERN, and ERN-S, respectively. The adjusted odds ratio for adherence was lowest for SM (0.69), which was statistically significant compared with ERN-S (1.43), but not ERNL (1.00) or ERN (0.74). Persistence outcomes were poor in all groups. By the fourth quarter, patients receiving ERN-S (OR 1.31) had significantly greater persistence than those receiving ERN (OR 0.41) and SM (0.61), but not those receiving ERNL (OR 1.00).

Managed care patients tended to be adherent to chronic lipid-lowering therapies, based on a mean MPR greater than 0.8. However, most patients failed to persist for at least 6 months.