Primary care usual and supplemental provider type: Are there differences in patient's intermediate diabetes outcomes?

Conference: 
SAPC ASM 2018 - London
Talk Code: 
P2.87
Presenter: 
Christine M. Everett
Co-authors: 
Valerie A. Smith, DrPH2,3; Perri A. Morgan, Ph.D., PA-C1; David Edelman, MD, MHS2,4; Courtney H. Van Houtven, Ph.D. 2,3; Sandra L. Woolson, MPH2; Theodore S. Z. Berkowitz, MS2; Cristina C. Hendrix, DNS, GNP-BC2,5,6; Brandolyn S. White, MPH2; George L. Jackson, Ph.D., MHA2,3,4
Author institutions: 
1-Physician Assistant Program, Duke University, Durham, NC, USA 2-Center for Health Services Research in Primary Care, Durham Veterans Affairs Health Care System, Durham, NC, USA 3-Department of Population Health Sciences, Duke University, Durham, NC, USA 4-Division of General Internal Medicine, Duke University, Durham, NC, USA 5-Geriatric Research Education and Clinical Center, Durham Veterans

Problem

The Veterans Affairs (VA) health system utilizes Patient-Aligned Care Teams with a primary care provider (PCP) that may be a doctor, nurse practitioner (NP), or physician associate (PA). Each PCP is responsible for a patient panel. However, PCPs may provide supplemental visits to patients assigned to other PCPs within the same clinic. This study examined whether there are differences in diabetes outcomes among patients with different types of primary and supplemental providers.

Approach

The study included adult diabetes patients receiving primary care within the VA system in 2012 and 2013. A patient’s PCP was defined as the provider most often visited in 2012. We examined the relationship between the PCP’s and supplemental providers’ professions (MD only; MD PCP+ NP supplement; MD PCP+PA supplement; NP PCP+ MD supplement; NP PCP, no MD; PA PCP+ MD supplement; PA PCP, no MD) for hemoglobin A1c (HbA1c) control, systolic blood pressure (SBP), and low-density lipoprotein cholesterol (LDL-C), in 2013. Hierarchical linear mixed models with random intercepts to account for clustering by VA facility and PCP were used to analyze continuous outcomes. Logistic regression models fit with generalized estimating equations and an exchangeable correlation structure and empirical standard errors were fit to dichotomous outcomes. Control variables included gender, age, race, ethnicity, marital status, homelessness, co-pay status, mental health diagnoses, health status (diagnostic cost group), travel distance to clinic, availability of specialized diabetes services at the clinic, rurality of the clinic, and region of the U.S. A priori thresholds for clinical importance/significance for differences in outcome were set for interpretation.

Findings

The sample included 611,790 patients. Patient outcomes for primary and supplemental provider are compared to doctor-only care (see table). HbA1c SBP LDL-C Clinical Importance Clinical Importance Clinical Importance Threshold 0.3% Threshold: 3.0 mmHg Threshold: 5.0mg/dL Difference Difference Difference % (95% CI) mmHg (95% CI) mg/dL (95% CI) MD only (reference) (N=409,703) - - - - - -MD PCP + NP supplement (N=40,078) 0.01 (-0.01, 0.03) 0.04 (-0.13, 0.21) 0.61 (0.22, 0.99)MD PCP + PA supplement (N=24,814) 0.04 (0.02, 0.07) -0.08 (-0.30, 0.14) 0.16 (-0.35, 0.66)NP PCP + MD supplement (N=32,320) 0.01 (-0.004, 0.03) 0.17 (-0.004, 0.34) 1.90 (1.51, 2.29)PA PCP + MD supplement (N=14,431) 0.03 (0.004, 0.06) -0.17 (-0.42, 0.09) 1.40 (0.82, 1.99)NP PCP no MD (N=66,395) -0.06 (-0.07, -0.04) -0.39 (-0.52, -0.26) 0.81 (0.51, 1.12)PA PCP no MD (N=24,049) -0.03 (-0.06, -0.01) -0.17 (-0.37, 0.03) 0.53 (0.06, 0.99)No clinically important variation in outcomes based on the profession of the patient’s PCP or supplemental provider were found.

Consequences

These findings suggests that NPs and PAs may safely deliver primary care to patients with diabetes in a range of roles.

Submitted by: 
Christine Everett
Funding acknowledgement: 
This research was supported by a grant from Department of Veterans Affairs (VA), Health Services Research and Development Service IIR 13-063.This work was also supported by the Center of Innovation for Health Services Research in Primary Care (CIN 13-410) at the Durham VA Health Care System.