Reliance on Veterans Affairs outpatient care by Medicare-eligible veterans.

OBJECTIVE: To examine longitudinal changes in Medicare-eligible veterans' reliance on the Department of Veterans Affairs (VA) healthcare system for primary and specialty care over 4 years.
METHODS: We merged VA administrative and Medicare claims data to examine outpatient use during fiscal years (FY) 2001 to 2004 by 15,520 Medicare-eligible veterans who used VA primary care in FY2000. Reliance on VA outpatient care was defined as the proportion of total (VA/Medicare) visits received in VA for primary or specialty care.
RESULTS: Of 869,000 primary and specialty care visits in the study period, 39% occurred within VA and 77% were specialty care. Reliance on VA primary care was substantially higher than specialty care (66% vs. 50% in FY2001; P<0.001). Reliance on VA primary and specialty care decreased over time (57% vs. 31% in FY2004; P<0.001). Significant shifts occurred at both extremes of VA reliance. From FY2001 to FY2004, the proportion of patients in the top decile of reliance on VA primary care decreased from 39% to 31%, whereas the proportion in the bottom decile doubled from 8% to 18%. Similarly, the proportion of patients in the top decile of reliance on VA specialty care decreased from 24% to 13%, whereas the proportion in the bottom decile doubled from 22% to 47%.
CONCLUSIONS: Reliance on VA primary and specialty care among VA primary care patients decreased substantially over time, particularly for specialty care. Increasing use of non-VA services may complicate VA's implementation of patient-centered medical home models and performance measurement.