Physicians, NPs, and PAs Provide Same Quality Care for Chronic Disease

Diana Phillips

November 20, 2018

Patients with diabetes who receive their primary care from nurse practitioners (NPs) and physician assistants (PAs) have similar intermediate outcomes as those who receive their care from primary care physicians, according to a study published online on November 19 in Annals of Internal Medicine.

The findings, reported by George L. Jackson, PhD, MHA, of the Durham Veterans Affairs Health Care System and Duke University, both in Durham, North Carolina, and colleagues, suggest that increased reliance on PAs and NPs for chronic disease management can expand access to primary care services while maintaining quality standards, the authors write.

To examine potential differences in intermediate diabetes outcomes among patients of physician, NP, and PA primary care providers (PCPs), the investigators analyzed nationwide administrative data from the VA’s electronic health record (EHR). The analysis included information from 368,481 adults with diabetes being treated by 3487 physicians, 1445 NPs, and 443 PAs across 568 VA primary care centers.

Patients were included in the analysis if they had a diabetes diagnosis and at least 1 VA inpatient admission or at least 2 VA outpatient visits in fiscal year 2012, and filled a prescription for insulin or an oral hyperglycemic agent in the same year. To be included, patients also had to have had an outpatient visit with a diabetes diagnosis in fiscal year 2013, reflecting a long enough duration for a PCP to reasonably affect outcomes, the authors note.

The outcomes of interest were the associations between provider type and mean hemoglobin A1c (HbA1c), systolic blood pressure (SBP), and low-density lipoprotein cholesterol (LDL-C) levels in fiscal year 2013. In addition to these continuous measures, the researchers considered dichotomous controls based on 2013 clinical practice guidelines, including mean HbA1c concentration less than 7%, mean SBP less than 130 mm Hg, and mean LDL-C level below 2.59 mmol/L (100 mg/dL).

Of the full patient sample, 74.9% received primary care from a physician, while 18.2% and 6.9% received primary care from NPs and PAs, respectively.

At follow-up, approximately 45% of patients achieved an HbA1c level of less than 7%, 42% reached their systolic blood pressure target of less than 130 mm Hg, and 72% attained their LDL-C goal of less than 2.59 mmol/L (100 mg/dL).

Although there were some statistically significant differences in mean HbA1c, SBP, and LDL-C values, and the degree to which patients met control targets across provider type, "we estimated no differences across PCP types that met our a priori definitions of clinical significance," the authors report.

There were also no clinically significant differences in odds for the control of the three dichotomous intermediate outcomes or for simultaneous control of all three intermediate outcomes, which, compared with physicians, had an odds ratio of 1.04 (95% confidence interval [CI], .99 - 1.09) for NPs and .98 (95% CI, .91 - 1.04) for PAs.

In addition, the weighted average proportions of patients with diabetes who used endocrinology or specialty services were similar across provider type (8.5% of NP patients, 9.8% of PA patients, and 9.2% of physician patients).

Further, the authors note that the results remained consistent in analyses that included only medically complex patients (Diagnostic Cost Group score higher than 2.0).

The generalizability of the study findings to the general public may be limited by the nature of the study population, which was predominantly male, and the VA model of care. "Compared with many health care systems in the United States, the VA makes greater use of strategies that may diminish disparities in provider care quality, such as patient-centered medical homes, team-based care involving staff other than the PCP, comprehensive EHRs, and extensive quality monitoring," the authors explain. "The possibility exists that greater use of such strategies as patient-centered medical homes may be associated with enhanced orientation and residency programs for NPs and PAs compared with other health systems."

The consistency of outcomes across provider types "is hardly surprising," Anne L. Peters, MD, of the Keck School of Medicine of the University of Southern California Los Angeles, writes in an accompanying editorial. "The VA was the first health system in the United States to use PAs, and both NPs and PAs have been fully integrated into the VA's care structure. Other analyses have shown similar, if not better, results for these healthcare workers—particularly NPs—in providing primary care."

What is noteworthy, Peters says, is the role of primary care providers in diabetes management. "In some respects, diabetes is the perfect chronic disease model to use in assessing intermediate outcomes of care. Hemoglobin A1c (HbA1c) and lipid levels, along with blood pressure readings, are all numeric and easily measured. However, organizations, such as the American Diabetes Association, recommend that diabetes management be undertaken by a team, not simply by a physician acting in isolation."

The “team” includes an expanded interdisciplinary group of professionals, such as certified diabetes educators, pharmacists, registered dietitians, therapists, physical and occupational therapists, exercise physiologists, and podiatrists, who help patients reach and maintain their targets and personal goals, Peters explains. "To a large degree, the success of a PCP—whether a physician, an NP, or a PA—depends on the ancillary diabetes services available to his or her patients.

"Given the right system—with resources to provide education and support, along with referral to an endocrinologist or a diabetes team if needed, and including more innovative programs, such as telehealth, online programs, and device-based data transfer and support—persons with diabetes can achieve their goals," Peters contends.

She concludes that health systems should reevaluate how they perceive and use NPs and PAs in practice. "[I]t is time to stop calling NPs and PAs 'midlevel' providers, as is common in certain systems. Nurse practitioners and PAs are competent PCPs in their own right and should be fully accepted as such."

Drs Jackson and Edelman report receiving grants from the VA during the conduct of the study. Dr Peters reports receiving grants or personal fees from the following companies: AstraZeneca, Dexcom, Mannkind, Eli Lilly, BI, Novo Nordisk, Sanofi, Livongo, Merck, Abbott Diabetes Care, Omada Health, and Lexicon, .

The study was funded primarily by VA Health Services Research and Development.

Ann Intern Med. doi:10.7326/M17-1987



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