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IIR 14-054 – HSR&D Study

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IIR 14-054
Optimizing the Value of Primary Care Delivered by Nurse Practitioners
Chuan-Fen Liu MPH PhD
VA Puget Sound Health Care System Seattle Division, Seattle, WA
Seattle, WA
Funding Period: December 2014 - May 2018

Nurse practitioners (NPs) account for 20% of the VA primary care provider workforce and provide more than 2 million primary care visits a year. Research supports that primary care NPs provide safe, effective care comparable to that provided by physicians (MDs) in general populations. However, VA patients are more clinically complex requiring more intensive clinical management compared with the general population. Research on NP performance in VA primary care is limited.

The study aimed to conduct a comprehensive assessment of NP performance by comparing patients cared for by NPs with those cared for by physicians (MDs). Aim 1 examined differences in utilization and costs; Aim 2 compared patient satisfaction and clinical outcomes; and Aim 3 assessed the perceptions and experiences of care under NPs using semi-structured interviews with patients and primary care providers.

Aims 1 and 2: We used a retrospective cohort design using VA administrative databases and the VA Survey of Healthcare Experiences of Patients (SHEP). The study sample included 806,434 VA primary care patients of MDs who were reassigned to either an MD (n=696,404) or an NP (n=110,030) when their provider left the system in calendar years 2010-2013. We compared patient outcomes between provider types one year after the reassignment. Aim 1 examined utilization and cost by analyzing clinic visits, hospitalizations, and total outpatient and inpatient costs. Aim 2 examined patient outcomes for three disease cohorts, including glycemic control for diabetes (n=207,297), lipid control (LDL) for ischemic heart disease (IHD, n=113,278), and blood pressure (BP) control for hypertension (n=357,987). We assessed patient satisfaction among those who responded to a SHEP survey after reassignment (n=20,996). To estimate the differences between NP and MD care, we used generalized linear models, controlling for baseline patient socio-demographics, comorbidity, geographic region, VAMC provider FTEs by specialty and clustering patient-level observations by primary care clinic.

Aim 3: We conducted semi-structured telephone interviews with VA patients who were recently reassigned to a different primary care provider and with VA primary care providers. We interviewed 31 PCPs (14 NPs and 17 MDs) and 28 patients (10 cared for by NPs and 18 cared for by MDs) recruited from VA facilities in both full and restricted scope of practice states. Themes related to perceptions of NPs were investigated using inductive and deductive content analysis of transcripts.

Aim 1: Patients who lived farther away from VA, lived in rural areas, or received care in CBOCs were more likely to be reassigned to NPs. However, socio-demographic characteristics and comorbidity were similar between patients who were reassigned to NPs or MDs.

One year after reassignment, NP patients were less likely to have any primary care (91% vs. 93%; adjusted percentage point difference [APPD] -1.3 [CI:-1.92 to -0.68]), any specialty care (31% vs. 37%; APPD -2.2 [CI:-3.10 to -1.33]), any hospitalization (8% vs. 9%; APPD -0.8 [CI:-1.24 to -0.436]), and any hospitalization for ambulatory care sensitive conditions (1.1% vs. 1.3%; APPD -0.2 [CI:-0.33 to -0.09]). Among users, NP patients had fewer primary care visits (4.9 vs. 5.1 visits; adjusted difference -0.36 visits [CI:-0.53 to -0.18]) and specialty care visits (4.5 vs. 4.9 visits; adjusted difference -0.19 visits [CI:-0.32 to -0.07]) than MD patients. The magnitude of these differences was small. There was no significant difference between NP and MD patients in having any mental health visit (28% vs. 29%), any metabolic panel test (63% vs. 65%), and any diagnostic or stress echo (1.2% vs. 1.3%). Finally, there were no significant differences between NP and MD patients in total VA outpatient cost ($4,432 vs. $4,858; adjusted difference -$114 [CI:-$231 to $3]) and total VA cost ($6,704 vs. $7,210; adjusted difference -$271 [CI: -$584 to $40]).

Aim 2: Most of the clinical outcomes evaluated were not statistically significantly different between NP and MD patients. Among diabetic patients, NP patients were slightly less likely to have a hemoglobin A1C measure (88% vs. 89%; APPD -1.0 [CI:-1.41 to -0.67]), but there were no significant differences in having a normal A1C (70% vs. 72%), having any LDL measure (85% vs. 86%), and having a normal LDL (70% vs. 62%; APPD -0.6 [CI:-1.48 to 0.26]). Among patients with IHD, there were no significant differences between NP and MD patients in having any LDL measure (88% vs. 88%) and having a normal LDL (70% vs. 72%). Among patients with hypertension, there was no significant difference between NP and MD patients in having a normal BP (72% vs. 73%). Finally, there was no significant difference in patient-reported satisfaction from SHEP between the two groups.

Aim 3: Three main findings emerged from qualitative interviews: 1) NPs were perceived by both patients and PCPs as providing more patient-centered care and better at patient education. 2) Patient satisfaction and preference was tied to NPs' patient-centeredness. 3) The accrued practice experience of individual NPs, rather than provider type, was perceived by both NPs and MDs as an important determinant of proficiency in primary care delivery and managing patient workload.

This was the first study to conduct a comprehensive assessment of primary care NPs. This study is particularly timely and policy-relevant because VA gave all NPs full practice authority in 2017. The study showed that, one year after patients were reassigned, NP patients had fewer VA primary care and specialty care visits than MD patients, but the differences were small. There were no differences in VA costs, clinical outcomes, and patient-reported satisfaction. Though NPs were perceived as comparable to MDs in most ways, patients' satisfaction and preference for the holistic, patient-centered care provided by NPs was a distinct difference. Similarities in PCPs' perceptions suggest that NPs and MDs generally work well together. The study shows that NPs may be able to provide comparable primary care to MDs regarding quality of care, healthcare utilization, and patient experiences. The study results provide important insights in the potential impacts of the full NP practice authority in VA.


Journal Articles

  1. Moldestad M, Greene PA, Sayre GG, Neely EL, Sulc CA, Sales AE, Reddy A, Wong ES, Liu CF. Comparable, but distinct: Perceptions of primary care provided by physicians and nurse practitioners in full and restricted practice authority states. Journal of Advanced Nursing. 2020 Nov 1; 76(11):3092-3103.
  2. Liu CF, Hebert PL, Douglas JH, Neely EL, Sulc CA, Reddy A, Sales AE, Wong ES. Outcomes of primary care delivery by nurse practitioners: Utilization, cost, and quality of care. Health services research. 2020 Apr 1; 55(2):178-189.

DRA: Health Systems
DRE: Treatment - Comparative Effectiveness
Keywords: none
MeSH Terms: none

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