Diabetes is a common chronic condition among Veterans requiring regular healthcare visits to both primary care providers and specialists. Although the Veterans Health Administration (VHA) offers a spectrum of integrated healthcare services, most veterans utilize both VHA and private sector healthcare providers. As has been reported, this dual-system use has the potential to impede coordination of care and may result in poorer outcomes. On the other hand, having coverage for services in two systems may result in increased choice and improved access to care for some Veterans.
Preventable hospitalizations (PHs) are considered a reflection of poor quality ambulatory care and lack of access to timely primary care. Using PHs as our outcome of interest, we attempted to assess the impact of dual system use on the health outcomes of Veterans with diabetes dually enrolled in VHA and Medicare. Given the previously reported low reliance of veterans on VHA ambulatory care, we also evaluated the association between reliance on VHA ambulatory care and Veterans' outcomes. In addition, we explored variability in state-level VHA and private sector preventable hospitalization rates in our cohort.
1. Among veteran clinic users with diabetes, examine the role of fragmented care at the veteran level and care coordination at the facility-level on the risk of preventable hospitalizations;
2. Among veteran clinic users with diabetes, analyze veteran-level and facility-level factors associated with the relationship between preventable hospitalizations and healthcare expenditures;
3. Develop prototype user-friendly maps of geographic variation in healthcare expenditures, dual VHA/Medicare use, and preventable hospitalizations among VHA users with diabetes.
Using data from VHA Corporate Data Warehouse (CDW) and the VA Information Resource Center (VIReC) Center for Medicare and Medicaid Services, we conducted a dynamic retrospective cohort study with calendar years 2004-2010 serving as the study period. The study population consisted of Veterans with diabetes mellitus, aged 66 years or older, and dually enrolled in VHA and Medicare.
Our outcome of interest was any PH experienced by the patient during the outcome years 2006-2010, adapted from the Agency for Healthcare Research and Quality's (AHRQ) definition of the Prevention Quality Indicators (PQI).
We defined reliance on VHA as the proportion of all non-urgent outpatient visits that were made to VHA facilities (VHA visits /(VHA visits + Medicare visits)). We adapted the fragmentation of care index used by Liu et al.: ((total outpatient visits)^2 - ((number of Medicare outpatient visits)^2 + (number of VHA outpatient visits)^2) / (total outpatient visits*(total outpatient visits -1)).
For state level analyses, we aggregated patient information to the state level. We calculated PH rates (PHRs) by dividing the total number of unique patients in each state who experienced at least one episode of a PH during the outcome year by the number who were hospitalized during the outcome year. We distinguished between total PHR (Medicare and VHA PHR combined) and system-level PHR (i.e., Medicare PHR and VHA PHR).
We used global Moran's I and the Univariate LISA to identify and locate clustering of PHRs among states. We used multivariable ordinary least squares regression (controlling for age and sex), and geographically weighted regression and a generalized additive model (controlling for geographic patterns) to evaluate the association between reliance on VHA ambulatory care and PHRs at the state level.
We used a logistic regression model to measure the association between PHs and care fragmentation while controlling for demographic characteristics, socioeconomic status, comorbidities, and intermediate level health measures at the patient level, patient population size and care coordination measures at the facility level, and area resource measures at the county level. We performed this analysis for outcome years 2008-2010 using only the hospitalized subjects in our cohort. Care coordination was measured at the assigned facility based on responses to the 2007 VHA Clinical Practice Organizational Survey (CPOS) administered by Yano et al.
The cohort (sample size range: 529,031 to 576,500 for each outcome year) primarily consisted of males aged 73-77 years. Of those patients who utilized inpatient services (sample size range: 149,027 to 155,553), 17% or less had at least one hospital stay at a VHA facility. The cohort's reliance on VHA ambulatory care at the state level ranged from 13.92% to 67.78%. Approximately 30% of those hospitalized experienced at least one preventable hospitalization during any given outcome year.
The state-level total PHR varied from 21% to 37% from 2006 to 2010. The VHA PHR ranged from 18% - 60%. The Medicare PHR ranged from 19% - 38%. We found significant clustering of low total PHR and Medicare PHR (global Moran's Is > 0.20; p-value <0.05 in all years) among states in the western US from 2006 to 2010. A cluster of high total PHRs and MC PHRs was inconsistently present around the states of Illinois, Indiana and Ohio. Our findings are consistent with state level PHRs reported for Medicare enrollees in the general population. Reliance on VHA ambulatory care was generally not associated with PHRs at the state level.
We found residence in highly rural areas (highly rural vs. urban: OR=1.25, CI:1.13-1.39) to be positively associated with PHs. We did not find a significant association between facility level care coordination measures and PHs. There are two possible explanations for this. First, our care coordination measures were based on self-reports from providers, which may be biased based on their perception. Second, given that most of our subjects received more than two-thirds of their care in the private sector, care coordination efforts in the VHA may have limited impact PHs, most of which also occur in the private sector.
We found an unexpected association between greater care fragmentation and lower risk of PHs (OR=0.72, CI: 0.66-0.78). Almost all previous studies have measured care fragmentation at the provider level and/or have accounted for the sequence of visits between various providers. Since our measure of care fragmentation detects care dispersion at the system level, we may be measuring care access rather than care fragmentation with our index.
Our findings indicate the importance of considering both VHA and private sector healthcare utilization in assessing outcomes and for resource allocation and healthcare delivery. Further analysis is necessary to clarify the context in which fragmentation and coordination measures are reliable.
- Rose DE, Rowneki M, Sambamoorthi U, Fried D, Dwibedi N, Tseng CL, Jani N, Yano EM, Helmer DA. Variations in VA and Medicare Use Among Veterans With Diabetes: Impacts on Ambulatory Care Sensitive Conditions Hospitalizations for 2008, 2009, and 2010. Medical care. 2019 Jun 1; 57(6):425-436.
- Helmer DA, Rowneki M, Feng X, Tseng CL, Rose D, Soroka O, Fried D, Jani N, Pogach LM, Sambamoorthi U. State-Level Variability in Veteran Reliance on Veterans Health Administration and Potentially Preventable Hospitalizations: A Geospatial Analysis. Inquiry : A Journal of Medical Care Organization, Provision and Financing. 2018 Jan 1; 55:46958018756216.