The Impact of Patient-Centered Medical Homes on Quality of Care and Medication Adherence in Patients with Diabetes Mellitus

BACKGROUND: Current evidence suggests that patient-centered medical homes (PCMHs) potentially increase overall quality of disease management, including preventive care. However, there are mixed findings regarding quality of diabetes care, and little evidence exists with respect to the effect of PCMHs on medication adherence in patients with diabetes. OBJECTIVE: To investigate associations between PCMHs and process measures of diabetes care, as well as adherence to oral hypoglycemic agents (OHAs) in patients with diabetes in a nationally representative U.S. sample. METHODS: Using the 2009-2013 longitudinal data files from the Medical Expenditure Panel Survey, adult diabetes patients were identified. Patients whose usual sources of care have all PCMH features at baseline (i.e., enhanced access after hours and online, shared decision making, and enhanced patient engagement) were categorized as the PCMH group, which was compared with patients without PCMH features. Process measures of diabetes care included ≥ 2 hemoglobin A1c tests and ≥ 1 cholesterol test, foot examination, dilated eye examination, and flu vaccination during 1 year of follow-up. Medication possession ratio (MPR) during follow-up was calculated for patients with OHAs without any insulin use, with MPR ≥ 80% considered to be adherent to OHAs. Univariate and multivariate regression models considering sampling strata and weights were used to examine the association between the PCMH and study outcomes. RESULTS: A total of 3,334 patients with diabetes was identified, representing 61 million U.S. lives. The mean (SE) age was 61.6 (0.3) years, and 52.4% of patients were female. The mean (SE) years of having diabetes was 12.0 (0.2) years. Approximately 11.4% of the patients were categorized as the PCMH group at baseline, and only 3.6% of those patients remained in the PCMH group for 2 years. Of the diabetic patients identified, only 26.9% met all of the diabetes care process measure criteria defined in this study. A higher proportion of patients met process measure criteria in the PCMH group compared with the non-PCMH group (33.8% vs. 26.0%, respectively, P = 0.015). The weighted mean MPR (95% CI) of OHAs from the 2 groups were not statistically different (0.68, 95% CI = 0.63-0.74 for the PCMH group; 0.77, 95% CI = 0.72-0.82 for the non-PCMH group, P = 0.675), resulting in 47.4% of adherent patients in the study population. Overall, the PCMH group was associated with improvement in the process measures of diabetes care (adjusted odds ratios [OR] = 1.42, 95% CI = 1.06-1.91). The effect was greater among the patients who stayed in the PCMH group for 2 years (OR = 2.09, 95% CI = 1.27-3.45); were aged < 65 years (OR = 2.19, 95% CI = 1.47-3.28); or had less than 3 comorbid conditions (OR = 2.38, 95% CI = 1.46-3.88). However, the PCMH group was not associated with an increased adherence to OHAs (P = 0.495) or an increase in MPR (P = 0.570). CONCLUSIONS: Patients with all PCMH features were associated with improvement in the process measures of diabetes care, but not in adherence to OHAs. Future studies should investigate the mechanism of PCMHs in overall quality of care, as well as medication adherence.