Majority of Male VA Enrollees Similar to Medicare Beneficiaries, Suggesting Greater Generalizability of Research Findings

BACKGROUND:
Historically, the VA patient population has been disproportionately male and more likely to have military service-related injuries, mental illness, and lower income than non-VA patient populations. Therefore, research studies of VA healthcare enrollees have been considered to have limited generalizability to other non-VA populations. This is the first study to assess the extent to which Veterans enrolled in VA healthcare have similar demographics and health characteristics as individuals with Medicaid, Medicare, and/or private insurance coverage. Investigators used data from 77,525 individuals who participated in the 2013 National Health Interview Survey (NHIS), administered annually by the Centers for Disease Control and Prevention, to track a wide array of health-related variables, such as health insurance enrollment, healthcare use, and health conditions and behaviors. Investigators also conducted subgroup analyses among males only.

FINDINGS:

• A majority of male Veterans enrolled in VA healthcare were similar in both demographics and health characteristics compared to Medicare beneficiaries, but this overlap decreased when comparing Veterans to individuals enrolled in Medicaid or those with private insurance.
• The proportion of overlap between VA and non-VA propensity scores was 21%, 34%, and 41% for the Medicaid, privately insured, and Medicare comparison populations, respectively.
• When restricting the analysis to males, the proportion of overlap increased to 28% for Medicaid enrollees, to 39% for privately insured adults, and to 55% for Medicare beneficiaries.
• When restricting the analysis to elderly males (age 65+), the proportion of overlap increased from 55% to 65% for Medicare beneficiaries, suggesting that 2 of every 3 elderly male VA enrollees had a male beneficiary enrolled in Medicare sharing a similar set of characteristics.

IMPLICATIONS:

• Findings of intervention studies conducted among VA healthcare enrollees may be generalized to some non-VA populations, particularly male Medicare enrollees. Further, effective interventions developed in elderly and/or male non-Veteran populations may be applicable to comparable VA users. Authors suggest that future work should continue to monitor the comparability of VA and non-VA populations, particularly as the VA healthcare system serves an increasingly younger and diverse population.

LIMITATIONS:

• Study analyses included all VA enrollees because of the inability to identify active VA healthcare users in the NHIS data.
• Estimates of VA coverage in the NHIS may be undercounted because of the framing of survey questions ascertaining health insurance coverage.

AUTHOR/FUNDING INFORMATION:
Dr. Wong is supported by an HSR&D Career Development award, and Dr. Maciejewski is supported by an HSR&D Research Career Scientist award. Dr. Wong is part of HSR&D's Center of Innovation for Veteran-Centered and Value-Driven Care, Seattle, WA, and Dr. Maciejewski is part of HSR&D's Center for Health Services Research in Primary Care, Durham, NC.

Wong E, Wang V, Liu C-F, Hebert P, and Maciejewski M. Do Veterans Health Administration Enrollees Generalize to Other Populations? Medical Care Research and Review. November 20, 2015; ePub ahead of print.