Nonadherence to Statins Impacts Medicare Spending

Medication nonadherence costs the US healthcare system nearly $300 billion annually. Studies have shown that patients who adhere to medication regimens have fewer hospitalizations, lower costs, and lower mortality when compared with nonadherent patients.

Medicare Advantage plans have an incentive to work to increase medication adherence now that the Centers for Medicare & Medicaid Services (CMS) awards bonus payments to plans based on population adherence to chronic medications. These CMS ratings are based on a proportion of plan beneficiaries who achieve a proportion of days covered (PDC) of 0.8 or above for 3 classes of medications: statins, renin angiotensin system antagonists, and oral hypoglycemic agents.

For patients prescribed statins, approximately 50% are adherent 6 months after initiation, according to studies. A new study used an individualized surveillance model to examine early detection of statin nonadherence and its affect on pay-for-performance models [PLoS One. 2013;8(11):e79611].

This retrospective database study of more than 210,000 beneficiaries initiating statins used de-identified medical and pharmacy claims on all Aetna commercial members with at least 1 year of continuous medical and pharmacy coverage between 2008 and 2011.

A logistic regression model was constructed to use statin adherence from initiation to day 90 to predict beneficiaries who would not meet the CMS PDC from day 91 to 365.

Patients were included in the study if they received a statin prescription and met criteria for dyslipidemia. Dyslipidemia was identified as: 2 claims with a diagnosis of lipid disorder unrelated to a laboratory claim; or low-density lipoprotein cholesterol >130 mg/dL; or total cholesterol >200 mg/dL; or high-density lipoprotein cholesterol <40 mg/dL; or triglycerides >150 mg/dL; or a claim with a Current Procedural Terminology Category II code for a lipid disorder.

A total of 217,928 patients met the study inclusion criteria. According to the study findings, lower adherence in the first 90 days was the strongest predictor of 1-year nonadherence (odds ratio, 25; 95% confidence interval, 23.7-26.5). The positive predictive value is 87.7% and the negative predictive value is 53.4%. For every 1000 beneficiaries, the model predicts poor adherence for 562.

The authors noted the following study limitations: treating medication fills as adherence is a simplified conception; the study does not address self-report, pill counts, or other measures of adherence; and future research in this area should use electronic medical record information and patient-reported adherence as additional outcome variables, either singularly or in combination.

The researchers concluded that to preserve Medicare Star ratings, plan managers should identify or develop programs to improve medication adherence. Early PDC was a strong indicator of future nonadherence—stronger than previously identified variables in other studies.