Intermediate Diabetes Outcomes in Patients Managed by Physicians, Nurse Practitioners, or Physician Assistants: A Cohort Study

Abstract

Background: Primary care provided by nurse practitioners (NPs) and physician assistants (PAs) has been proposed as a solution to expected workforce shortages.

Objective: To examine potential differences in intermediate diabetes outcomes among patients of physician, NP, and PA primary care providers (PCPs).

Design: Cohort study using data from the U.S. Department of Veterans Affairs (VA) electronic health record.

Setting: 568 VA primary care facilities.

Patients: 368 481 adult patients with diabetes treated pharmaceutically.

Measurements: The relationship between the profession of the PCP (the provider the patient visited most often in 2012) and both continuous and dichotomous control of hemoglobin A1c (HbA1c), systolic blood pressure (SBP), and low-density lipoprotein cholesterol (LDL-C) was examined on the basis of the mean of measurements in 2013. Inverse probability of PCP type was used to balance cohort characteristics. Hierarchical linear mixed models and logistic regression models were used to analyze continuous and dichotomous outcomes, respectively.

Results: The PCPs were physicians (n = 3487), NPs (n = 1445), and PAs (n = 443) for 74.9%, 18.2%, and 6.9% of patients, respectively. The difference in HbA1c values compared with physicians was -0.05% (95% CI, -0.07% to -0.02%) for NPs and 0.01% (CI, -0.02% to 0.04%) for PAs. For SBP, the difference was -0.08 mm Hg (CI, -0.34 to 0.18 mm Hg) for NPs and 0.02 mm Hg (CI, -0.42 to 0.38 mm Hg) for PAs. For LDL-C, the difference was 0.01 mmol/L (CI, 0.00 to 0.03 mmol/L) (0.57 mg/dL [CI, 0.03 to 1.11 mg/dL]) for NPs and 0.03 mmol/L (CI, 0.01 to 0.05 mmol/L) (1.08 mg/dL [CI, 0.25 to 1.91 mg/dL]) for PAs. None of these differences were clinically significant.

Limitation: Most VA patients are men who receive treatment in a staff-model health care system.

Conclusion: No clinically significant variation was found among the 3 PCP types with regard to diabetes outcomes, suggesting that similar chronic illness outcomes may be achieved by physicians, NPs, and PAs.

Primary funding source: VA Health Services Research and Development.