Graduation Year

2015

Document Type

Dissertation

Degree

Ph.D

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Aging Studies

Major Professor

Hongdao Meng, Ph.D.

Co-Major Professor

Lisa M. Brown, Ph.D.

Committee Member

Robert Campbell, Ph.D.

Committee Member

Debra Dobbs, Ph.D.

Committee Member

Kathryn Hyer, Ph.D.

Committee Member

Joshua M. Wiener, Ph.D.

Keywords

home based primary care, homebound, hospitalizations, house calls, physician, propensity score matching

Abstract

Background: Among patients with multiple chronic conditions, care coordination and integration remains one of the major challenges facing the U.S. health care system. A home-based, patient-centered primary care program has been offered through the Veterans Health Administration (VHA) since the 1970s for frail veterans who have difficulty accessing VHA clinics. The VHA Home Based Primary Care (VHA HBPC) aims to integrate primary care, rehabilitation, disease management, palliative care, and coordination of care for frail individuals with complex, chronic diseases within their homes. Early research suggested that VHA HBPC was associated with positive outcomes (e.g., reduced resource use and patient satisfaction). However, evidence regarding the effect of the VHA HBPC program on health services use (especially hospital and nursing home use), expenditures, and other patient outcomes remains limited. The present study is designed to fill this gap as the rise in the number of veterans with complex health care needs will likely increase in the coming decades.

Objectives: The current study aimed to examine the impact of VHA HBPC on health services use, expenditures, and mortality among a cohort of new VHA HBPC enrollees identified in the national VHA data system. The specific aims of this study were: 1) to examine the effect of VHA HBPC on major health service use (hospital, nursing home, and outpatient care) paid for by the Veterans Administration; 2) to examine the effect of VHA HBPC on total health services expenditures; and 3) to examine whether VHA HBPC enrollees experienced similar mortality and survival as compared to a matched concurrent cohort.

Methods: This study used a retrospective cohort design. A new VHA HBPC enrollee cohort (the treatment group) and a propensity matched comparison cohort (the comparison group) were identified from VHA claims in fiscal years (FY) 2009 and 2010 and were followed through FY 2012. Data on health service use, expenditures, and mortality/survival data were obtained via the VHA administrative datasets (i.e., Decision Support System, Purchased Care, and Vital Status Files). Propensity scores of being enrolled in the VHA HBPC were generated by a logistic regression model controlling for potential confounders. After 41,244 matched pairs were determined adequate through several diagnostic methods, means tests, relative risk analyses, and generalized linear models were used to estimate the effect of VHA HBPC on outcomes. Additionally, a Cox proportional hazards regression model was used to estimate the effect of VHA HBPC on survival. Subgroup analyses were conducted stratifying by age (85 and older), comorbidities (2 or more), and the receipt of palliative care. Based on the results of the original analyses, a series of sensitivity analyses were conducted that modified the described sample selection criteria and matching algorithm.

Results: Analyses of the original cohort revealed that VHA HBPC patients had significantly higher risks of being admitted into a hospital (RR 1.53, 95% CI 1.51-1.56) or nursing home (RR 1.65, CI 1.50 - 1.81). The average total expenditures during the study period were significantly higher for the VHA HBPC group as compared to the control group ($85,808 vs. $44,833, respectively; p < .001). In terms of mortality and survival, VHA HBPC enrollees had higher mortality (RR 1.45, CI 1.43 - 1.47), and shorter survival (HR 1.89, CI 1.86 - 1.93) as compared to those in the comparison group. Subgroup analyses found that these relationships generally remained when stratified by age 85 or older or having two or more comorbidities. However, for those who received palliative care, VHA HBPC participants had significantly lower risk of VHA hospitalization overall (RR 0.84, CI 0.81 - 0.87) and immediately prior to death. Finally, exploratory post-hoc analysis suggested that VHA HBPC recipients were at higher risk of VHA hospitalization at 30 (RR 1.11, CI 1.06 - 1.16), 60 (RR 1.16, CI 1.11 - 1.20), and 90 days (RR 1.16, 1.12 - 1.21) prior to death relative to the comparison group. After selecting only those that had a baseline hospitalization and refining the matching algorithm to account for time to death and additional comorbidities, VHA HBPC participants who had been enrolled in the program for at least six months had lower risks for hospital (RR 0.89, CI 0.88 - 0.90) and nursing home admissions (RR 0.74, CI 0.67 - 0.81). However, total expenditures remained significantly higher among those in VHA HBPC relative to the comparison group ($89,761 vs. $85,371, respectively; p < .001).

Discussion: This study found that without accounting for important covariates such as initial hospitalization, time to death, and a range of comorbidities, VHA HBPC was associated with higher health service use, higher expenditures, higher mortality, and shorter survival as compared to a similar group of patients not receiving VHA HBPC. After accounting for these factors, VHA HBPC was associated with a lower risk of nursing home use, and after six months, VHA HBPC was associated with lower risk of both nursing home and hospital use. These findings suggest that while VHA HBPC may improve quality of life and patient satisfaction through patient-centered integrated primary care, it may not generate cost savings for the healthcare system. Future research is needed to understand variation in program implementation and how this affects the impact of VHA HBPC on service use and cost.

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