Background and aims: An accurate and feasible method to assess adherence to statin therapy is needed. We developed a novel blood test to identify reduced statin adherence and compared statin adherence determined by a single blood test to pharmacy registry data.
Methods: In a retrospective cohort study of patients prescribed atorvastatin or simvastatin during hospitalization for a coronary heart disease event, a single blood sample was collected median 18 months later. Patients were unaware of the forthcoming statin analyses. Statin adherence was determined by drug concentration measurements using liquid chromatography mass spectrometry and the Norwegian Prescription Database by gaps in statin dispenses.
Results: Out of 451 patients, 9 % (n = 39) had reduced adherence (≥2 doses omitted) determined by the blood test. Among those classified as adherent by the blood test, only 0.7 % (n = 3) had a treatment gap ≥90 days during the preceding three months, whereas 28 % (n = 115) during the entire follow-up period (median 5.9 years). Of 39 patients classified with reduced adherence by the blood test, 28 % (n = 11) had treatment gaps ≥90 days during the preceding three months, and 66 % (n = 26) during the entire study period. Patients classified with reduced adherence by the blood test, but not registry data, had numerically more coronary events prior to the index event compared to adherent patients.
Conclusions: In coronary outpatients, high adherence to statin treatment measured by a novel blood test aligns with adherence assessed by pharmacy registry. The blood test emerges as a promising tool for enhancing lipid management in clinical practice.
Keywords: Adherence; Coronary heart disease; LC/MS-MS; LDL-Cholesterol; Pharmacy prescription registry; Statin.
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