Objective: To estimate the extent of under use of coronary angiography and to determine whether women, ethnic minorities and poor and uninsured patients are less likely than their counterparts to receive necessary coronary angiography.
Design: Retrospective cohort study employing chart review and patient interviews.
Setting: Four teaching hospitals: three government owned (public) and one private university medical center in Los Angeles, California.
Patients: Three hundred and fifty two patients who had a positive exercise stress test between 1 January 1990 and 30 June 1991 and met explicitly defined criteria for the necessity of coronary angiography established by a multidisciplinary expert panel.
Main outcome measures: Percentage of patients who received necessary coronary angiography within 3 and 12 months following exercise stress testing, adjusted for demographic and clinical characteristics using logistic regression.
Results: Overall 43% received necessary coronary angiography within 3 months and 56% within 12 months of the stress test. Women were less likely than men to receive necessary coronary angiography. Adjusted odds ratio (AOR) 0.54, 95% confidence interval (CI) 0.34-0.90 for angiography within 3 months of the stress test; AOR 0.47, 95% CI 0.29-0.77 for angiography within 12 months of the stress test. Public hospital patients underwent necessary coronary angiography less often than private hospital patients. AOR 0.40, 95% CI 0.23-0.79 for within 3 months; AOR 0.52, 95% CI 0.30-0.91 for within 12 months.
Conclusions: Under use of coronary angiography can be measured and occurs to a significant degree. It is important to develop standards of quality to address and safeguard against under use of necessary medical care.