Factors of hyperlipidemia medication adherence in a nationwide health plan.

Objectives: To evaluate the factors associated with nonadherence in a nationally representative sample of patients receiving lipid-lowering therapy (LLT).

Study Design: Retrospective database analysis of treatment-naive (1 year without LLT claim) hyperlipidemia patients evidenced by a new pharmacy claim for lipid-lowering therapy.

Methods: Pharmacy and medical claims data were analyzed for currently enrolled members receiving a new LLT from 2007 to 2008. Adherence was defi ned as percentage of days covered (PDC) and values %lt;80% were used to categorize nonadherent patients. Independent variables included patient demographics, pharmacy utilization, and medical conditions. Stepwise logistic regression was used to predict the odds of nonadherence. Laboratory data variables were incorporated in an exploratory sub-analysis to test the robustness of the original model.

Results: Adherence with LLT was estimated in 88,635 patients. Sixty-fi ve percent of patients were nonadherent (mean PDC = 0.33). Compared with statins, patients treated with bile acid sequestrants were 6.75 times as likely to be nonadherent (P <.001). Significant (P <.05) predictors of nonadherence included age 45 to 55 years (ref: age >75 y) (odds ratio [OR]: 1.11); prior diabetes diagnosis (OR: 1.15); and unique pharmacies used (OR = 1.10). Significant factors reducing nonadherence include male gender (OR: 0.77); previous heart attack (OR: 0.82); prior adherent behavior (OR: 0.89); and unique physicians seen (OR: 0.97). Compared with no copayment, patients with $5 to $30 copayments had a significant reduction in the likelihood of nonadherence.

Conclusions: Medication adherence remains poor in patients receiving LLT. Treatment outcomes and healthcare resource use may be improved by prioritizing adherence programs in at-risk patient populations.