Factors Associated With Seeking Physician Care by Medicare Beneficiaries Who Receive All Their Primary Care From Nurse Practitioners

Abstract

Background: A shortage of primary care physicians has led to the alternative strategy of nurse practitioners (NPs) as primary care providers for the growing elderly population. Many states have implemented policies that allow NPs to practice independently with no physician oversight. Little is known about the continuity of primary care provided by NPs. Objective: To examine rate and correlates of switching from exclusive NP primary care to receiving some or all primary care from physicians. Design: A retrospective cohort study. Participants: Medicare beneficiaries (n = 38 618) with diabetes, congestive heart failure, or chronic obstructive pulmonary disease who received all their primary care from NPs in 2007. Main Measures: Multivariable logistic regression model was used to assess patient and disease characteristics associated with switching from sole NP primary care in 2007 to receiving some or all primary care from physicians between 2008 and 2010. Results: Of elderly patients receiving all their primary care from NPs in 2007, 53.8% switched to receiving some or all primary care from physicians in 2008-2010. The switching patients had less comorbidity before the switch and were more likely to reside in metropolitan areas, ZIP code areas with high education or states with the most restriction on NP scope of practice. In multivariable analyses, significant predictors of switching included one of the following within 30 days before the switch: emergency room visits (odds ratio [OR] = 1.55, 95% confidence interval [CI] = 1.44-1.68), hospitalization (OR = 1.13, 95% CI = 1.02-1.25), new diagnosis of heart attacks (OR = 5.52, 95% CI = 4.33-7.02), pneumonia (OR = 4.84, 95% CI = 3.71-6.32), atrial fibrillation (OR = 3.99, 95% CI = 2.93-5.44), stroke (OR = 2.94, 95% CI = 2.31-3.74), or cancer (OR = 2.65, 95% CI = 1.94-3.63). Conclusions: About half of Medicare patients under exclusive NP primary care switched to physicians for some or all primary care over a 3-year period. Future study is needed to understand the reasons for switching.

Keywords

nurse practitioner primary care Medicare discontinuity of care

Introduction

Having one physician as a usual source of primary care is key to effective primary care of older patients with multiple coexisting diseases that require care coordination across multiple health care settings.^1-5 In a study of adult primary care network of 181 primary care physicians (PCPs), patients who did not identify one physician as their usual source of care were less likely to receive guideline-recommended diabetes care and cancer screenings.³ Older patients who see different PCPs at each visit are more likely to experience medical errors and potentially avoidable acute care visits, and have high health care cost.^2,6-10 To reduce such care fragmentation in older patients, the Affordable Care Act (ACA) authorized implementation of patient-centered medical home delivery models and other alternative health care models.^11-13 Success for these models depends on long-term continuity of primary care and a stable patient-clinician relationship.

A major challenge to long-term continuity of primary care is the growing shortage of PCPs; nurse practitioners (NPs) are increasingly being used to address this shortage.^11,14,15-22 Between 1998 and 2010, the proportion of Medicare recipients billed for outpatient care by NPs increased 9.5%, with the greatest increase in states with no restriction on NP practice.¹⁵ Some states such as Arizona and Maryland have policies that allow NPs to practice independently with no physician oversight.¹⁶ In addressing the shortage of PCPs, the federal government under ACA provided $50 million per year (from 2012 to 2015) to expand the training of NPs in primary care.¹⁷ Several studies have examined continuity of care among PCPs,^3-5,23 but there have been no population-based studies of long-term continuity of primary care among older patients receiving all their primary care from NPs. Understanding factors associated with longitudinal continuity of primary care in this population is critically important in improving quality and decreasing cost of care. The present study examined rates and correlates of switching from exclusive NP primary care to receiving care from PCPs between 2008 and 2010 among Medicare beneficiaries with diabetes, congestive heart failure (CHF), or chronic obstructive pulmonary disease (COPD) who received all their primary care from NPs in 2007.

Methods

Establishment of the Cohort Study

We identified all Medicare beneficiaries with diabetes, CHF, or COPD in 2006-2007 from the CMS Chronic Disease Data Warehouse (CCW). To select the NP cohort, we identified all patients aged 66 years or older who received all of their primary care from NPs in 2007. We identified the patients through bill records for 2 or more outpatient evaluation and management (E&M) services by NPs and with no outpatient E&M services from MDs (general practitioner, family physician, general internist, or geriatrician). We excluded patients whose original entitlements were based on disability or end-stage renal disease. Also excluded were patients who stayed in a nursing home in 2007 and those without continuous enrollment in parts A and B or covered in a health maintenance organization (HMO) in 2006 and 2007.

Study Outcome

Patients were followed up from 2008 to identify discontinuity of primary care from NPs. Discontinuity of care was defined as a switch from exclusive NP primary care to receiving any care from a PCP any time between 2008 and 2010. Patients were censored at death, loss of coverage or the end of the study (December 31, 2010).

Measures

The demographic information on patients’ age, gender, and race/ethnicity was obtained from Medicare enrollment files. We used a Medicaid indication in the enrollment file as a proxy for low socioeconomic status. Education for ZIP code areas was obtained from the 2010 Census data and categorized by quartiles. The Elixhauser comorbidity measures were generated from inpatient and outpatient claims in 2007 and the comorbidity sum for patients were the summation of all Elixhauser comorbidity measures excluding CHF, CPOD, and diabetes with or without chronic complications. Number of provider visits; whether patients saw a cardiology, endocrinology or pulmonary specialist; and number of hospitalizations in 2007 were generated. The size of residential area was categorized using Rural-Urban Continuum Codes that distinguish metropolitan counties by size and nonmetropolitan counties by degree of urbanization and proximity to metropolitan areas. State regulations of NP practice were classified into 5 categories from least to most restricted.¹⁵

To further explore potential factors associated with discontinuity of primary care, we examined rates of acute hospitalization or an emergency room (ER) visit in the 30 days prior to switching to an MD primary care. We also assessed whether patients had a new diagnosis of major health events in the 30 days prior to care switch. The incident events were cancer (International Classification of Diseases, Ninth Revision [ICD-9]: 140-239), stroke (ICD-9: 430-437), heart attack (ICD-9: 410-414), hip fracture (ICD-9: 820), atrial fibrillation (ICD-9: 427.3) and pneumonia (ICD-9: 480-486). The incident event was defined by a primary diagnosis in either inpatient or outpatient claims for the event and no such event in the previous 12 months. To ensure that the follow-up time was comparable to the 30-day look-back period between patients who switched to physician care (the switch group) and those who stayed with NP care (stay group), we randomly assigned the follow-up time to those in the stay group based on the distribution of follow-up time from the switch group.

Statistical Analyses

Using t test for continuous variables and chi-square test for categorical variables, we compared characteristics of patients who continuously received all primary care from NPs to those who switched to receiving some or all primary care from physicians. To examine potential factors associated with switching from sole NP primary care to physician primary care, we used a multivariable logistic regression model to evaluate the independent relationships between patient characteristics and the odds of switching to MDs for primary care. All tests of statistical significance were 2-sided (P < .05). Analyses were performed with SAS version 9.3 (SAS Institute, Cary, NC).

Results

The study cohort included 38 618 Medicare beneficiaries with CHF, COPD, or diabetes who received primary care from NPs in 2007. Table 1 shows the characteristics of the beneficiaries grouped according to whether they switch care from sole NP to any MD (switch group) or stayed with NP care (stay group) any time between 2008 and 2010. Of the patients receiving NP care, 53.8% switched to MDs for their primary care. Patients in the switch group were more likely to be female, younger, reside in metro areas, reside in ZIP codes with higher education, and reside in states with most restrictions on the scope of NP practice. They were also more likely to have diabetes or liver disease, and have endocrinology specialty consult. They were less likely to be black and impoverished. The switch group had fewer comorbidities and prior hospitalizations than the stay group, but more NP provider visits in the previous year. The switch group participants were less likely to have CHF, COPD, pulmonary circulation disease, peripheral vascular disease, neurological disorder, renal failure, AIDS, anemia, peptic ulcer, weight loss, and cancer.

Table 1.

Characteristics of Medicare Patients Who Received All Their Primary Care From Nurse Practitioners (NPs) in 2007 Stratified According to Whether the Patients Received Some or All of Their Care From Primary Care Physicians or Continue With NP Primary Care Between 2008 and 2010.

Variables	n		Switch to Physicians (%)	Stay With NPs (%)	P
N	38 618		20 766	17 852
%			53.8	46.2
Age in years
66-74	15 477		54.8	45.2	<.0001
75-84	17 190		54.4	45.6
85+	5951		49.3	50.7
Gender
Female	24 144		55.3	46.7	<.0001
Male	14 474		51.2	48.8	<.0001
Race
Whites	33 399		53.6	46.4	<.0001
Blacks	2793		51.9	48.1
Hispanics	1414		54.5	45.5
Other	1012		62.5	37.5
Medicaid eligibility
No	31 577		54.6	45.4	<.0001
Yes	7 041		50.2	49.8	<.0001
Proportion of education >12 years
Q1 (lowest)	9539		51.9	48.1	<.0001
Q2	9524		53.0	47.0
Q3	9345		53.4	46.6
Q4 (highest)	9587		56.6	43.4
Rural/urban
Metro	23 059		56.8	43.2	<.0001
Nonmetro urban	13 148		49.8	50.2
Rural	2411		46.1	53.9
State regulation
1 (least restrictive)	6484		53.8	46.2	<.0001
2	6337		53.0	47.0
3	10 418		52.4	47.6
4	8718		54.0	46.0
5 (most restrictive)	6661		56.3	43.7
Prior hospitalization
0	28 007		54.6	45.4	<.0001
1	6764		52.6	47.4
2	2348		51.7	48.3
3+	1499		46.7	53.3
Previous provider visit			9.9 ± 7.2	8.9 ± 7.2	<.0001
Specialty visit
Cardiology	Yes	13 604	53.9	46.1	.75
Cardiology	No	25 014	53.7	46.3	.75
Pulmonary	Yes	4346	53.4	46.6	.58
Pulmonary	No	34 272	53.8	46.2	.58
Endocrinology	Yes	2658	58.9	41.1	<.0001
Endocrinology	No	35 960	53.4	46.4	<.0001
Conditions
Diabetes	Yes	26 055	54.6	45.4	<.0001
Diabetes	No	12 563	52.1	47.9	<.0001
Congestive heart failure	Yes	12 860	51.2	48.8	<.0001
Congestive heart failure	No	25 758	55.1	44.9	<.0001
COPD	Yes	7600	51.4	48.6	<.0001
COPD	No	31 018	54.4	45.6	<.0001
Number of conditions
1	31 542		54.6	45.4	<.0001
2	6255		50.7	49.3
3	821		46.5	53.5
Comorbidity sum
0	7130		54.7	45.3	<.0001
1	14 551		54.5	45.5
2	8340		54.4	45.6
3+	8597		51.2	48.8
Comorbidity
Valvular disease	Yes	3216	52.7	47.3	.19
Valvular disease	No	35 402	53.9	46.1	.19
Pulmonary circulation disease	Yes	828	45.1	54.9	<.0001
Pulmonary circulation disease	No	37 790	54.0	46.0	<.0001
Hypertension	Yes	27 103	53.9	46.1	.61
Hypertension	No	11 515	53.6	46.4	.61
Peripheral vascular disease	Yes	3735	50.2	49.8	<.0001
Peripheral vascular disease	No	34 883	54.1	45.9	<.0001
Paralysis	Yes	281	50.2	49.8	.23
Paralysis	No	38 337	53.8	46.2	.23
Neurological disorders	Yes	1264	44.9	55.1	<.0001
Neurological disorders	No	37 354	54.1	45.9	<.0001
Hypothyroidism	Yes	4694	54.8	45.2	.12
Hypothyroidism	No	33 924	53.6	46.4	.12
Renal failure	Yes	3086	51.7	48.3	.02
Renal failure	No	35 532	53.9	46.1	.02
Liver disease	Yes	232	60.8	39.2	.03
Liver disease	No	38 386	53.7	46.3	.03
Peptic ulcer	Yes	21	33.3	66.7	.06
Peptic ulcer	No	38 597	53.8	46.2	.06
Acquired immune deficiency syndrome	Yes	15	26.7	73.3	.04
Acquired immune deficiency syndrome	No	38 603	53.8	46.2	.04
Rheumatoid arthritis	Yes	1005	55.0	45.0	.42
Rheumatoid arthritis	No	37 613	53.7	46.3	.42
Coagulopthy	Yes	920	52.5	47.5	.43
Coagulopthy	No	37 698	53.8	46.2	.43
Obesity	Yes	1216	54.0	46.0	.86
Obesity	No	37 402	53.8	46.2	.86
Weight loss	Yes	609	48.4	51.6	.01
Weight loss	No	38 009	53.9	46.1	.01
Fluid and electrolyte disorders	Yes	3414	50.5	49.5	<.0001
Fluid and electrolyte disorders	No	35 204	54.1	45.9	<.0001
Chronic blood loss anemia	Yes	438	48.6	51.4	.03
Chronic blood loss anemia	No	38 180	53.8	46.2	.03
Lymphoma	Yes	387	52.2	47.8	.53
Lymphoma	No	38 231	53.8	46.2	.53
Metastatic cancer	Yes	401	41.6	58.4	<.0001
Metastatic cancer	No	38 217	53.9	46.1	<.0001
Solid tumor without metastasis	Yes	3250	50.3	49.7	<.0001
Solid tumor without metastasis	No	35 368	54.1	45.9	<.0001
Deficiency anemias	Yes	5458	50.9	49.1	<.0001
Deficiency anemias	No	33 160	54.2	45.8	<.0001
Alcohol abuse	Yes	178	57.9	42.1	.24
Alcohol abuse	No	38 440	53.7	46.3	.24
Drug abuse	Yes	39	48.7	51.3	.53
Drug abuse	No	38 579	53.8	46.2	.53
Psychoses	Yes	810	52.8	47.2	.59
Psychoses	No	37 808	53.8	46.2	.59
Depression	Yes	1720	52.7	47.3	.38
Depression	No	36 898	53.8	46.2	.38

Table 2 shows the rates of acute care events and new diagnoses in the 30 days before switch in the switch group compared with rates in the stay group. Patients in the switch group were more likely to have experienced hospitalization (8% vs 4.5%) and ER visits (13.8% vs 6.5%) in the 30 days before they switched to MD care. In the 30 days before they switched, they were also more likely to have been newly diagnosed with cancer, stroke, heart attack, atrial fibrillation, and pneumonia.

Table 2.

Hospitalization and Emergency Room (ER) Visits and New Diagnoses in Medicare Patients 30 Days Before the Patients Switched From Sole Nurse Practitioner (NP) Primary Care to Receiving Any Care From a Primary Care Medical Doctor (MD), 2008-2010.

Variables	Switch to MD	Stay With NP^a	P
N	20 766	17 852
Length of follow-up months (mean ± SD)	12.3 ± 9.9	10.8 ± 9.8
Hospitalization and ER (%)
Hospitalization	8.0	4.5	<.0001
Preventable hospitalization	2.4	1.1	<.0001
Nonpreventable hospitalization	5.9	3.5	<.0001
ER visits	13.8	6.5	<.0001
Specific disease (new case) (%)
Principal diagnosis
Cancer (excluding skin cancer)	0.86	0.30	<.0001
Stroke	1.80	0.50	<.0001
Heart attack	2.56	0.45	<.0001
Hip fracture	0.13	0.11	.42
Atrial fibrillation	1.35	0.29	<.0001
Pneumonia	2.12	0.37	<.0001
Pneumonia (excluding 481-484.6)	2.08	0.36	<.0001
Any position on diagnosis
Cancer (excluding skin cancer)	1.24	0.38	<.0001
Stroke	2.53	0.66	<.0001
Heart attack	3.38	0.69	<.0001
Hip fracture	0.16	0.12	.28
Atrial fibrillation	1.71	0.41	<.0001
Pneumonia	2.60	0.56	<.0001

To ensure that the follow-up time was comparable to the 30-day look-back period between patients who switched to physician care (the switch group) and those who stayed with NP care (stay group), we randomly assigned the follow-up time to those in the stay group based on the distribution of follow-up time from the switch group.

Table 3 presents the associations between patient characteristics and odds of switching from NP primary care to MD primary care. In the multivariable analyses, significant predictors of switching from NP care to MD primary care include female gender, not being on Medicaid, high education, residence in a metro area or in a state with most restrictions on NP practice, fewer prior hospitalization and comorbidities, and frequent clinic visits to the NP. Other significant predictors of switching from NP to MD care included ER visits (odds ratio [OR] = 1.55, 95% confidence interval (CI) = 1.44-1.68) or hospitalization (OR = 1.13, CI = 1.02-1.25) in the 30 days prior to switch. Odds of switching from NP to MD also increased significantly after patients were newly diagnosed with heart attacks (OR = 5.52, 95% CI = 4.33-7.02), pneumonia (OR = 4.84, 95% CI = 3.71-6.32), atrial fibrillation (OR = 3.99, 95% CI = 2.93-5.44), stroke (OR = 2.94, 95% CI = 2.31-3.74), or cancer (OR = 2.65, 95% CI = 1.94-3.63). About 8% of variation in switching care from NP to MD was explained by the characteristics listed in Table 3.

Table 3.

Adjusted Odds Ratio (OR) From a Multivariable Analysis Estimating the Odds of Switching From Receiving All Primary Care From Nurse Practitioners in 2007 to Receiving Some or All Care From Primary Care Physicians Between 2008 and 2010.

	OR	95% CI
	OR	Lower Limit	Upper Limit
Age in years
66-74	Reference
75-84	0.95	0.91	1.00
85+	0.75	0.71	0.80
Female	1.24	1.18	1.29
Race
White	Reference
Black	0.99	0.91	1.08
Hispanic	1.08	0.97	1.22
Other	1.61	1.40	1.84
Medicaid eligibility	0.83	0.78	0.88
Proportion of education >12 years
Q1 (lowest)	Reference
Q2	1.02	0.96	1.08
Q3	1.02	0.96	1.09
Q4 (highest)	1.13	1.06	1.20
Rural/urban
Metro	Reference
Nonmetro urban	0.77	0.74	0.81
Rural	0.67	0.62	0.73
State regulation
1 (least restrictive)	Reference
2	1.00	0.93	1.07
3	1.06	1.00	1.14
4	1.10	1.02	1.18
5 (most restrictive)	1.19	1.11	1.28
Prior hospitalization
0	Reference
1	0.97	0.91	1.03
2	0.94	0.86	1.04
3+	0.77	0.69	0.87
Previous provider visit	1.03	1.02	1.03
Specialty visit
Cardiology	0.95	0.91	0.99
Pulmonary	0.87	0.81	0.93
Endocrinology	1.08	0.99	1.17
No. of conditions
1	Reference
2	0.85	0.80	0.90
3	0.75	0.64	0.87
Comorbidity sum
0	Reference
1	0.94	0.89	1.00
2	0.91	0.85	0.97
3+	0.77	0.71	0.84
Hospitalization*	1.13	1.02	1.25
Emergency room visit*	1.55	1.44	1.68
Principal diagnosis*
Cancer	2.65	1.94	3.63
Stroke	2.94	2.31	3.74
Heart attack	5.52	4.33	7.02
Hip fracture	0.81	0.43	1.52
Atrial fibrillation	3.99	2.93	5.44
Pneumonia	4.84	3.71	6.32

In the 30 days prior to the switch.

Discussion

About half of Medicare beneficiaries with NPs as their sole primary care provider in 2007 switched to receive some or all of their primary care from physicians between 2008 and 2010. The switch group patients were more likely to have been hospitalized or visited ER within 30 days prior to the switching, relative to the stay group patients. The switch group patients were also more likely than those in the stay group to have been newly diagnosed with cancer, stroke, heart attack, atrial fibrillation, and pneumonia in the 30 days before they switched. More Medicaid-eligible patients stayed with their NP primary care providers compared with non-Medicaid eligible patients; this may reflect the reluctance of some physicians to take on Medicaid patients for primary care.²⁴

Our finding of higher NP-to-MD switching in states with the most restrictions of NP practice is consistent with prior findings of lower likelihood of NP primary care when NP practice is restricted.¹⁵ The restrictions ranged from limitations on admitting patients to hospital, making referrals, ordering diagnostic tests to prescribing medications.¹⁵ Our study showed that NP-to-MD switching occurred more frequently after a patient experienced a hospitalization or ER visit. These acute care experiences, especially in the context of high NP practice restriction, may alter the patient perception of the ability of the NP provider to facilitate future tests, medications or hospital/ER transfers. A future qualitative study is needed to examine relationship between degree of NP practice restriction and domains of patient-perceived continuity of care such as relational and informational continuity (interpersonal trust and knowledge) that are not captured in quantitative study like ours.^23,25,26-31

Some of the patients who switched might still be cared for by NPs under a team model of care where NPs and MDs work together to care for older patients with multiple chronic diseases.^27-34 The NP-MD team model may best serve the needs of the switch group patients whose health conditions have become more complex following their recent hospitalizations or new diagnoses. Evidence showed that patients with multiple comorbidities experienced better outcomes at lower cost under a collaborative model of NPs and MDs.^32-36

One potential explanation for the switching after hospitalization or ER visits may be related to physician perceptions of quality of NP clinical skills. These perceptions may implicitly or explicitly encourage these hospitalized patients to switch to primary care physicians.^37-39 The number of NPs generally is increasing,¹⁵ so a decreasing population of NPs does not explain the high switch rate. Patients who switch after ER visits or hospitalizations may also switch because they feel they need to seek physician involvement after their acute care visits or new diagnoses, given that many of these visits are to emergency specialties.

There are several limitations to our study. Because we studied only fee-for-service Medicare patients, our findings may not be generalizable to younger populations or patients with commercial insurance. We may also not have captured all patients who received all their primary care from NPs. This possibility could arise in a group medical practice when the physician rather than the NP submits the higher billing charge under the MD name for care given by the NP. We also do not have data on quality of communication and patient trust, factors that are critical to longevity of the clinician-patient relationship.^23,25,26,40 Qualitative interviewing of NPs, physicians and patients may help clarify the perceived added value of physician primary care versus NP primary care versus team care, implicit and explicit biases in the health care system, and organizational and system barriers impeding continuity of care. ^27-31,41-46

Footnotes

Acknowledgements

The authors have no financial, personal or potential conflicts of interest to disclose. The funders had no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; or the preparation, review, or approval of the manuscript.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by Grant No. R24-HS022134 from the Agency for Healthcare Research and Quality, and Grant Nos. R01-AG033134, P30-AG024832, and UL1TR001439 from the National Institutes of Health.

Author Biographies

Michelle Y. Raji is a rising junior at Harvard University, Cambridge, Massachusetts where she studies Global Health, Health Policy, and English. She was a 2015 summer research intern in the Department of Preventive Medicine and Community Health at the University of Texas Medical Branch (UTMB), Galveston.

Nai-Wei Chen, PhD, is a biostatistician at the UTMB Department of Preventive Medicine and Community Health. His areas of expertise include analysis of Medicare and other large claims data, generalized linear mixed models, categorical data analysis, and longitudinal studies.

Mukaila Raji, MD MS, FACP, is Edgar Gnitzinger Distinguished professor of Aging and director of the UTMB Division of Geriatric Medicine. He is a board-certified geriatrician with over 15 years’ experience in comparative drug effectiveness and toxicity research, cognitive aging and disability, and health policy and outcomes.

Yong-Fang Kuo, PhD, is professor of Preventive Medicine and Community Health, and director of the UTMB Office of Biostatistics. She has over 15 years’ experience in health policy and outcomes, comparative effectiveness and toxicity research, hierarchical generalized linear mix modelling, and instrumental variable analysis.

References

Nyweide

Anthony

Bynum

. Continuity of care and the risk of preventable hospitalization in older adults. JAMA Intern Med. 2013;173:1879-1885.

Hussey

Schneider

Rudin

Fox

Lai

Pollack

. Continuity and the costs of care for chronic disease. JAMA Intern Med. 2014;174:742-748.

Atlas

Grant

Ferris

Chang

Barry

. Patient-physician connectedness and quality of primary care. Ann Intern Med. 2009;150:325-335.

Wolinsky

Bentler

Liu

. Continuity of care with a primary care physician and mortality in older adults. J Gerontol A Biol Sci Med Sci. 2010;65:421-428.

Adler

Vasiliadis

Bickell

. The relationship between continuity and patient satisfaction: a systematic review. Fam Pract. 2010;27:171-178.

van Walraven

Oake

Jennings

Forster

. The association between continuity of care and outcomes: a systematic and critical review. J Eval Clin Pract. 2010;16:947-956.

Peikes

Chen

Schore

Brown

. Effects of care coordination on hospitalization, quality of care, and health care expenditures among Medicare beneficiaries: 15 randomized trials. JAMA. 2009;301:603-618.

Liu

Einstadter

Cebul

. Care fragmentation and emergency department use among complex patients with diabetes. Am J Manag Care. 2010;16:413-420.

Schrag

Hanger

Elkin

Bickell

Bach

. Fragmentation of care for frequently hospitalized urban residents. Med Care. 2006;44:560-567.

10.

Frandsen

Joynt

Rebitzer

Jha

. Care fragmentation, quality, and costs among chronically ill patients. Am J Manag Care. 2015;21:355-362.

11.

US Department of Health & Human Services. Creating health care jobs by addressing primary care workforce needs. http://www.hhs.gov/healthcare/facts-and-features/fact-sheets/creating-health-care-jobs-by-addressing-primary-care-workforce-needs/index.html. Accessed March 25, 2016.

12.

Centers for Medicare & Medicaid Services. Fact sheet comprehensive primary care initiative. https://innovation.cms.gov/Files/fact-sheet/Comprehensive-Primary-Care-Initiative-Fact-Sheet.pdf. Accessed March 25, 2016.

13.

The Affordable Care Act supports patient-centered medical homes in health centers. http://www.hhs.gov/about/news/2014/08/26/the-affordable-care-act-supports-patient-centered-medical-homes-in-health-centers.html. Accessed March 25, 2016.

14.

US Department of Health and Human Services, Health Resources and Services Administration, National Center for Health Workforce Analysis. Projecting the Supply and Demand for Primary Care Practitioners Through 2020. Rockville, MD: US Department of Health and Human Services; 2013.

15.

Kuo

Loresto

Jr Rounds

Goodwin

. States with the least restrictive regulations experienced the largest increase in patients seen by nurse practitioners. Health Aff (Millwood). 2013;32:1236-1243.

16.

National Institute for Health Care Reform. Primary care workforce shortages: nurse practitioner scope-of-practice laws and payment policies. 2013. http://www.nihcr.org/pcp-workforce-nps. Accessed April 21, 2016.

17.

Fact sheet: creating health care jobs by addressing primary care workforce needs. https://www.whitehouse.gov/the-press-office/2012/04/11/fact-sheet-creating-health-care-jobs-addressing-primary-care-workforce-n. Accessed March 25, 2016.

18.

Kinnersley

Anderson

Parry

. Randomized controlled trial of nurse practitioner versus general practitioner care for patients requesting “same day” consultations in primary care. BMJ. 2000;320:1043-1048.

19.

Venning

Durie

Roland

Roberts

Leese

. Randomized controlled trial comparing cost effectiveness of general practitioners and nurse practitioners in primary care. BMJ. 2000;320:1048-1053.

20.

Shum

Humphreys

Wheeler

Cochrane

Skoda

Clement

. Nurse management of patients with minor illnesses in general practice: multicenter, randomized controlled trial. BMJ. 2000;320:1038-1043.

21.

Dierick-van Daele

Metsemakers

Derckx

Spreeuwenberg

Vrijhoef

. Nurse practitioners substituting for general practitioners: randomized controlled trial. J Adv Nurs. 2009;65:391-401.

22.

Fan

Burman

McDonell

Fihn

. Continuity of care and other determinants of patient satisfaction with primary care. J Gen Intern Med. 2005;20:226-233.

23.

Hill

Twiddy

Hewison

House

. Measuring patient-perceived continuity of care for patients with long-term conditions in primary care. BMC Fam Pract. 2014;15:191. doi:10.1186/s12875-014-0191-8.

24.

Decker

. In 2011 nearly one-third of physicians said they would not accept new Medicaid patients, but rising fees may help. Health Aff (Millwood). 2012;31:1673-1679.

25.

Chao

. Continuity of care: incorporating patient perceptions. Fam Med. 1988;20:333-337.

26.

Gulliford

Cowie

Morgan

. Relational and management continuity survey in patients with multiple long-term conditions. J Health Serv Res Policy. 2011;16:67-74.

27.

Martínez-González

Djalali

Tandjung

. Substitution of physicians by nurses in primary care: a systematic review and meta-analysis. BMC Health Serv Res. 2014;14:214.

28.

Martínez-González

Tandjung

Djalali

Huber-Geismann

Markun

Rosemann

. Effects of physician-nurse substitution on clinical parameters: a systematic review and meta-analysis. PLoS One. 2014;9:e89181. doi:10.1371/journal.pone.0089181.

29.

Kuo

Goodwin

Chen

Lwin

Baillargeon

Raji

. Diabetes mellitus care provided by nurse practitioners vs primary care physicians. J Am Geriatr Soc. 2015;63:1980-1988.

30.

Kuo

Chen

Baillargeon

Raji

Goodwin

. Potentially preventable hospitalizations in Medicare patients with diabetes: a comparison of primary care provided by nurse practitioners versus physicians. Med Care. 2015;53:776-783.

31.

Mundinger

Kane

Lenz

. Primary care outcomes in patients treated by nurse practitioners or physicians: a randomized trial. JAMA. 2000;283:59-68.

32.

Ladden

Bodenheimer

Fishman

. The emerging primary care workforce: preliminary observations from the primary care team: learning from effective ambulatory practices project. Acad Med. 2013;88:1830-1834.

33.

Everett

Thorpe

Palta

Carayon

Bartels

Smith

. Physician assistants and nurse practitioners perform effective roles on teams caring for Medicare patients with diabetes. Health Aff (Millwood). 2013;32:1942-1948.

34.

Ghorob

Bodenheimer

. Sharing the care to improve access to primary care. N Engl J Med. 2012;366:1955-1957.

35.

Porter

Pabo

Lee

. Redesigning primary care: a strategic vision to improve value by organizing around patients’ needs. Health Aff (Millwood). 2013;32:516-525.

36.

Milani

Lavie

. Health care 2020: reengineering health care delivery to combat chronic disease. Am J Med. 2015;128:337-343.

37.

Donelan

DesRoches

Dittus

Buerhaus

. Perspectives of physicians and nurse practitioners on primary care practice. N Engl J Med. 2013;368:1898-1906.

38.

American Academy of Family Physicians. Patient perceptions regarding health care providers. 2012. http://www.aafp.org/dam/AAFP/documents/about_us/initiatives/PatientPerceptions.pdf. Accessed March 25, 2016.

39.

American Academy of Family Physicians. Independent practice authority for NPs threatens to splinter care, undermine PCMH. http://www.aafp.org/news/inside-aafp/20120918nppolicyreport.html. Accessed March 25, 2016.

40.

Safran

Montgomery

Hong

Murphy

Rogers

. Switching doctors: predictors of voluntary disenrollment from a primary physician’s practice. J Fam Pract. 2001;50:130-136.

41.

Berglund

Gustafsson

Johansson

Bergenmar

. Nurse-led outpatient clinics in oncology care–Patient satisfaction, information and continuity of care. Eur J Oncol Nurs. 2015;19:724-730. doi:10.1016/j.ejon.2015.05.007.

42.

Fletcher

Sharma

Zhang

Kuo

Goodwin

. Trends in inpatient continuity of care for a cohort of Medicare patients 1996-2006. J Hosp Med. 2011;6:441-447. doi:10.1002/jhm.916.

43.

Uijen

Bischoff

Schellevis

Bor

van den Bosch

Schers

. Continuity in different care modes and its relationship to quality of life: a randomised controlled trial in patients with COPD. Br J Gen Pract. 2012:62;e422-e428.

44.

Planavsky

Mion

Litaker

Kippes

Mehta

. Ending a nurse practitioner-patient relationship: uncovering patients’ perceptions. J Am Acad Nurse Pract. 2001;13:428-432.

45.

Committee on the RWJF Initiative on the Future of Nursing, Institute of Medicine. The Future of Nursing: Leading Change, Advancing Health. Washington, DC: National Academies Press; 2010.

46.

Katz

McCoy

Sarrazin

. Does improved continuity of primary care affect clinician-patient communication in VA? J Gen Intern Med. 2014;29(suppl 2):S682-S688. doi:10.1007/s11606-013-2633-8.