Underuse of Cardiac Procedures: Do Women, Ethnic Minorities, and the Uninsured Fail To Receive Needed Revascularization?

Women, ethnic minorities, and the poor are less likely than non-poor white male patients to receive diagnostic and therapeutic cardiac procedures (1-14). The reported differences are substantial. For example, ratios of white to black recipients of coronary artery bypass graft (CABG) surgery of 2:1 or more have been found, even when analysis is restricted to patients who have received coronary angiography (5-8, 10-15). Such differences have been found for both discretionary and nondiscretionary procedures (16). The use of cardiac services is also lower in Hispanic patients (9), and ratios of male to female recipients ranging from 1.28 to 2.15 have been reported in population-based studies (1, 2) and studies from single institutions (4, 17). After adjustment for age and clinical severity of disease, however, these differences sometimes disappear (4). Use rates are not indicators of quality. Discrepancies in use rates may reflect differences in need, overuse in one group, or underuse in one group. The important question is not whether women and disadvantaged groups receive fewer treatments but whether they receive them when they need them. To evaluate the possible underuse of essential services in women and disadvantaged persons, we focused on the provision of CABG surgery and percutaneous transluminal coronary angioplasty (PTCA) in New York City because of the high percentages of ethnic minorities and low-income patients in that area. We used two standards to assess underuse of CABG surgery and PTCA: RAND expert panel necessity ratings and the presence of left main or three-vessel disease. We studied patients who received coronary angiography in public and private hospitals in New York City and asked three questions: Of the patients who need cardiac revascularization, what percentage do not receive it? Are rates of underuse higher among women, African-American patients, Hispanic patients, and uninsured persons? Finally, is underuse related to type of hospital ownership or to whether on-site CABG surgery and PTCA are available? Methods Necessity Criteria Explicit criteria for the determination of underuse were developed by the RAND expert panel in 1990 (18-20) (Appendix). After rating all of the possible indications [clinical scenarios] for CABG surgery and PTCA for appropriateness, the panel rated each appropriate indication for necessity. Revascularization was considered necessary for an indication if the panelists believed that 1) not providing revascularization for most patients with the indication would constitute improper care, 2) the likelihood of benefit from revascularization for patients with the indication would be significant, and 3) the magnitude of the benefit would not be small. A necessary rating implies that a physician is obligated to recommend revascularization for the given indication in the absence of contraindications or mitigating factors. Of the indications for CABG surgery or PTCA that were previously rated as appropriate by the panel, fewer than half (n=249) were rated as necessary. These indications are only 8% of all possible indications for CABG surgery and PTCA. We conducted a separate analysis for patients with left main or three-vessel disease. These conditions are considered by many to be indications for necessary revascularization because of evidence showing that CABG surgery provides a survival benefit in patients with these conditions. Study Sample The sample frame included all patients who had coronary angiography for suspected atherosclerosis in 1992. To obtain comparable numbers of patients from each disadvantaged group, we used a two-stage procedure to select hospitals and patients. Using data provided by the New York Department of Health, we excluded one hospital that performed only 89 angiography procedures in 1992; we then randomly selected hospitals in each of five strata defined by the volume of angiographic procedures performed and the percentages of African-American and Hispanic patients undergoing coronary angiography in 1992. We oversampled hospitals with high proportions of minority patients. The final hospital sample consisted of 13 of the 24 hospitals in New York City that provide coronary angiography. Nine of the 13 hospitals selected also provided revascularization. They are referred to here as on-site hospitals; the remaining 4 hospitals referred patients to other hospitals for revascularization and are referred to here as off-site hospitals. Eighty percent of patients who have angiography in New York City do so in an on-site hospital. All of the selected hospitals agreed to participate in our study. Within each hospital, we selected a stratified random sample of patients; strata were defined by ethnic group and sex. We restricted our study to patients identified in hospital records as African American, Hispanic, or white. Although these classifications do not represent homogeneous groups in a population as diverse as that of New York City, they do capture separately identifiable groups that are known to have problems with access to health care. Because the number of Asian patients and patients of other ethnic groups in these hospitals was too small to permit adequate sampling for our study, we excluded them. Hospitals differed markedly in terms of patient ethnicity. The proportion of nonwhite patients ranged from 3% to 87%, and most of the higher proportions were seen in hospitals that performed low volumes of revascularization procedures. To assess between-hospital variation, we oversampled patients in low-volume hospitals and oversampled minority patients in hospitals that served predominantly white populations. The analyses reported were reweighted to account for this two-step sampling strategy so that the reported results reflect the distribution of ethnic groups within the population. The final sample comprised 3404 patients. We anticipated that 20% of these patients would have indications that met the panel criteria for necessity; thus, our study had 80% power to detect the ethnicity- and sex-based differences of 15% to 20% that we expected to find. Hospitals located 3300 (97%) angiogram reports for the patients, and these reports were then abstracted to define the extent of coronary artery disease. We excluded 303 patients who previously had CABG surgery or PTCA and 1020 patients whose angiograms showed no vessel with at least 50% narrowing. We also excluded 448 patients whose angiograms showed one or more vessels with 50% stenosis but did not satisfy the panel definition of significant coronary artery disease, which required a reduction of 70% or more in at least one major vessel (except for the left main coronary artery, where 50% stenosis was considered significant disease). This left 1529 patients who met the panel criteria for significant coronary artery disease. Hospitals located medical records for 1475 (97%) of these patients. Record Abstraction The clinical and laboratory data needed to determine whether patients met the panel criteria for necessity of CABG surgery or PTCA were abstracted from patients' hospital records by trained nurses. Abstractors also recorded information indicating whether revascularization was received by, offered to, or refused by the patient. If the results of exercise stress testing were needed to determine necessity and were not in the medical record, we requested a report from the referring physician. We requested 43 stress test reports and obtained 33. The 10 patients without stress test reports were excluded from the analysis. On the basis of abstracted data, each patient was assigned to a specific indication that had previously been classified as necessary or not necessary by the panel. Of the 1475 patients with significant coronary artery disease, 631 met the panel criteria for necessary revascularization and formed the denominator for all further analyses. These 631 patients represented 105 indications, or 43% of the 249 indications for which the panel considered revascularization necessary. Assessing Outcomes We used multiple sources to determine whether patients obtained necessary revascularization. We matched patients to data reported to the New York State Cardiac Surgical and Angioplasty Reporting Systems (physicians are required to report all CABG and PTCA procedures to these systems). We also checked for information about revascularization in the hospital records and matched our data to the SPARCS (Statewide Planning and Research Cooperative System) database, which contains a record of all hospitalizations in New York State. Finally, we asked cardiologists at each study hospital whether patients had received revascularization. Hospital records rarely contained statements indicating that patients had refused CABG surgery or PTCA. Therefore, for patients who did not undergo revascularization, we asked the cardiologists whether revascularization had been recommended and, if so, whether it was refused. We were able to obtain this information for all but 33 patients (5%). Statistical Analysis We used multiple logistic regression to model the probability that a patient would receive a revascularization procedure (or have it recommended) as a function of hospital and several other independent variables. We calculated adjusted revascularization and recommendation rates by levels of each independent variable, except hospital, while controlling for the other variables in the tables. The adjusted rates were produced by direct standardization (21). For example, the adjusted revascularization rate for male patients is the mean across the entire sample (male and female) of the predicted probability of revascularization under the assumption that each person is male but retains all of his or her other characteristics. Consequently, any reported difference between male and female patients is due only to sex. Except for the on-site and off-site hospital revascularization and recommendation rates calculated for all hospit