Relationship Between Patient Medication Adherence and Subsequent Clinical Inertia in Type 2 Diabetes Glycemic Management

Abstract

OBJECTIVE—Clinical inertia has been identified as a critical barrier to glycemic control in type 2 diabetes. We assessed the relationship between patients' initial medication adherence and subsequent regimen intensification among patients with persistently elevated A1C levels.

RESEARCH DESIGN AND METHODS—We analyzed an inception cohort of 2,065 insured patients with type 2 diabetes who were newly started on hypoglycemic therapy and were followed for at least 3 years between 1992 and 2001. Medication adherence was assessed by taking the ratio of medication days dispensed (from pharmacy records) to medication days prescribed (as documented in the medical record) for the first prescribed hypoglycemic drug. Adherence was measured for the period between medication initiation and the next elevated A1C result measured at least 3 months later; intensification was defined as a dose increase or the addition of a second hypoglycemic agent.

RESULTS—Patients were aged (mean ± SD) 55.4 ± 12.2 years; 53% were men, and 19% were black. Baseline medication adherence was 79.8 ± 19.3%. Patients in the lowest quartile of adherence were significantly less likely to have their regimens increased within 12 months of their first elevated A1C compared with patients in the highest quartile (27 vs. 37%, respectively, with increased regimens if A1C is elevated, P < 0.001). In multivariate models adjusting for patient demographic and treatment factors, patients in the highest adherence quartile had 53% greater odds of medication intensification after an elevated A1C (95% CI 1.11–1.93, P = 0.01).

CONCLUSIONS—Among insured diabetic patients with elevated A1C, level of medication adherence predicted subsequent medication intensification. Poor patient self-management behavior increases therapeutic clinical inertia.