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150. Access to Clinically Necessary Angiography in VA Compared with Medicare: a National Comparison of Process and 3-Year Survival

LA Petersen, Houston Center for Quality of Care and Utilization Studies; SLT Normand, Harvard Medical School and Harvard School of Public Health; LL Leape, Harvard School of Public Health; M Volya, Harvard Medical School; BJ McNeil, Harvard Medical School

Objectives: To compare access to clinically necessary angiography in VA with traditional fee-for-service care under Medicare financing, we used clinical data collected by chart review from two cohorts discharged with acute myocardial infarction (AMI).

Methods: The first cohort was a stratified national random sample of male veterans age >= 65 discharged with the primary diagnosis of AMI (ICD-9-CM-410). The second cohort contained all males age >= 65 discharged with AMI from the states of CA, FL, MA, NY, OH, PA, and TX. Data on comorbid conditions and severity of AMI were collected on both samples using the Cooperative Cardiovascular Project data collection instrument. We studied 1,631 veterans in 81 VAMCs and 19,114 Medicare patients in 1,530 non-VA hospitals who were eligible for angiography more than 12 hours after admission but prior to discharge. We compared use of angiography, revascularization procedures, and 1- and 3-year mortality among all patients and those rated clinically necessary for angiography using established criteria.

Results: Among all patients eligible for angiography 12 hours or more after admission, 48.9% of Medicare and 38.3% of VHA patients underwent angiography during the index admission (P<0.001). The rates of revascularization procedures during the index admission, conditional upon undergoing angiography, were 33.9% of Medicare vs. 25.3% of VA for PTCA, for CABG, 27.1% of Medicare and 15.4% of VA, and for any revascularization the rates were 59.0% Medicare and 39.4% VA (all P <0.001). According to modified RAND criteria, 28.4% of Medicare patients and 43.4% of VHA patients met criteria for necessary angiography prior to discharge. Medicare patients who were rated necessary for angiography were more likely than the VHA patients who were rated as Necessary to undergo angiography (60.5% vs. 47.3%; P<0.001). The rates of revascularization procedures for these patients during the index admission, conditional upon undergoing angiography, were 33.1% of Medicare vs. 29.5% of VA for PTCA (P=0.18), for CABG, 32.3% of Medicare and 19.1% of VA, and for any revascularization the rates were 62.5% Medicare and 46.6% VA (both P <0.001). Despite these significant differences in procedure rates, there was no significant difference between the two groups in 1-year mortality (19.5% of Medicare vs. 19.1% of VHA necessary patients; P=0.78). Using pairs of matched necessary VHA and Medicare patients to control for illness burden, there was no significant difference in use of angiography (McNemar c2= 0.42, df = 1, p-value = 0.52). As in the unadjusted analyses, we also observed no significant difference in 1-year mortality (McNemar c2=0.42, df = 1, p-value = 0.52) or 3-year mortality (McNemar c2=0.29, df = 1, p-value = 0.59). Our findings did not change when we used ACC/AHA guideline clinical criteria to judge clinical need for angiography.

Conclusions: These findings suggest that practice pattern differences in use of angiography are being driven more by patient characteristics than by organizational differences between VA and non-VA care.

Impact: Reassuringly, such differences in practice are not accompanied by long-term mortality differences at up to 3 years after accounting for dissimilarities in population risk between the two cohorts.