Previous reports have suggested that blacks receive life-saving cardioprotective therapies less often than whites, probably because of a lower socioeconomic status, which leads to poor access to physicians. We questioned whether racial disparity existed in the Veterans Affairs Healthcare System. We examined the Veterans’ Integrated Service Network (VISN 16) database with regard to the prescription rates for 4 cardiovascular agents—aspirin, β blockers, statins, and angiotensin-converting enzyme inhibitors. The database, encompassing 474,565 patients (117,071 blacks and 357,494 whites), was analyzed. Cardioprotective drugs were prescribed significantly less often to black patients than compared to white patients (β blockers 19.7% vs 24.8%, odds ratio [OR] 0.74, 95% confidence interval [CI] 0.72 to 0.75; statins 20.5% vs 30.2%, OR 0.54, 95% CI 0.52 to 0.55; and angiotensin-converting enzyme inhibitors 27.7% vs 30.0%, OR 0.94, 95% CI 0.92 to 0.96; all p <0.0001, after adjustment for all covariates used in the analysis). Nonetheless, the prescription rates for aspirin were greater among the black patients than among the white patients (OR 1.31, 95% CI 1.27 to 1.35, p <0.001) after adjustment. The black patients received coronary artery bypass grafting less often than did the white patients (0.4% vs 1.21%, OR 0.40% to 0.48%, 95% CI 1.34 to 1.42, p <0.001). After adjustment for the use of cardioprotective drugs and coronary artery bypass grafting, black patients still had greater odds of developing angina (OR 1.38, 95% CI 1.34 to 1.42, p <0.001) and acute myocardial infarction (OR 1.11, 95% CI 1.03 to 1.19, p <0.006) than did white patients in the Department of Veterans Affairs Veterans’ Integrated Service Network 16 hospitals. In conclusion, the lower prescription rates of cardioprotective drugs and lower rates of coronary artery bypass grafting might be a partial basis for the high rates of cardiac morbidity among black patients.
It has been suggested that a racial bias might exist in the prescription of cardioprotective drugs that would account for the smaller decrease in coronary heart disease (CHD) mortality in black than in white patients. A very large number of patients are treated at the Department of Veterans Affairs hospitals. The patients in the Department of Veterans Affairs hospitals frequently return to their physicians for management of cardiac conditions, such as angina and acute myocardial infarction (AMI). If the veterans need cardiac procedures, such as cardiac catheterization or coronary artery bypass grafting (CABG), they are provided these at the nearest available Department of Veterans Affairs hospital. The healthcare providers in these hospitals have no financial incentive to withhold care from certain patients. The patients are often elderly and sick and have been receiving a number of drugs for a long period. On the basis of these considerations, we hypothesized that the discrepancies in the prescriptions of cardioprotective drugs and, hence, differences in outcome, would not be observed in the Department of Veterans Affairs hospitals, because all patients receive the same therapy at no or minimal cost to the patient.
Methods
The United States Veterans Affairs Healthcare System (Veterans Integrated Service Network [VISN] 16) provides care to >400,000 veterans annually. These patients receive their medical care and drugs free of charge or at minimal cost, ensuring a high degree of compliance with physician recommendations and follow-up visits. Furthermore, the Veterans Affairs Computerized Patient-Care Review System provides detailed information of patient demographics, co-morbidities, laboratory findings, and treatment to all caregivers. This computerized system also provides a unique opportunity to collect data from a large group of patients followed up for a prolonged period. The objective of the present study was to examine the VISN 16 patient care database with regard to use of cardioprotective drugs in blacks and whites.
The data were obtained from the VISN 16 Data Warehouse. The VISN 16 Data Warehouse contains clinical and demographic information for all patients cared for at the 10 medical centers included in the South Central Veterans Affairs Healthcare Network in the mid-south region of the United States. The Data Warehouse, implemented in 1996, electronically and automatically retrieves and stores data from all patients entered into the Veterans Affairs computerized system. These data include patient demographics, laboratory test results, vital signs, drugs prescribed, outpatient visit findings, hospitalizations, and International Classification of Diseases (ICD), Ninth Revision and Diagnosis Related Groups codes. The database contained data for approximately 1.5 million patients.
Access to the Data Warehouse is monitored and controlled by dedicated data administrators. The institutional review boards of the Central Arkansas Veterans Healthcare System, the related Research and Development Committee, and the VISN-wide committee, which regulates access to the Data Warehouse approved the present study.
The pertinent terms used in this study were aspirin, β blocker, statin, and angiotensin-converting enzyme (ACE) inhibitor users—patients in the cohort with a prescription for any of these drugs; hypertension—patients documented to have hypertension on chart review (generally systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg); diabetes mellitus—patients with a diagnosis with an ICD, Ninth Revision, code 250 prefix or a diagnosis with a 401, 405, or 458 prefix; dyslipidemia—patients with a diagnosis with a prefix of 272, including pure hypercholesterolemia, pure hypertriglyceridemia, mixed hyperlipidemia, and hyperchylomicronemia; smoker—patients who reported being a current or previous smoker; CABG—patients with a diagnosis with an ICD code 36.10 to 36.19; angina—patients with a diagnosis with an ICD code of 411.1 to 411.9 and 413.1 to 413.9; and AMI—patients with a diagnosis with an ICD code 410.0 to 410.9.
All analyses were performed using Statistical Analysis Systems, version 9.2, software (SAS Institute, Cary, North Carolina). An α level of 0.05 was established as a level of significance for all tests. Baseline comparisons between the 2 race groups and all univariate associations were performed using the 2-sample t test and chi-square test. Seven analytic models were constructed to examine the associations between race and cardiac drug prescriptions and morbidities and CABG. Each model consisted of cardiac drug prescription, morbidity (angina and AMI) or CABG as a binary outcome, race as the main independent variable under consideration, and other covariates that were used for adjustment purposes as independent or confounding factors. Multivariate associations between the selected covariates and 7 variables treated as outcomes were therefore examined using logistic regression models. The covariates used in the model included age, gender, income, depression, diabetes, hypertension, smoking status, and cardiac medications, as well as morbidities and CABG, and were not the outcome measure for a given model. Some covariates were used for adjustment purposes across all 7 models for consistency. The nesting of patients within sites was examined using the general estimating equation approach to a logistic model, with compound symmetry as a correlation structure. However, it did not improve any of the models significantly. Therefore, simpler models were adequate and were applied as such without the site variable.
Results
A total of 1,483,966 patients had data available. We excluded patients for whom the data on demographics were incomplete. We also excluded patients who reported they were Hispanic, Asian, Native American, or other and those who did not reveal their race. Complete data were available for 474,565 patients (117,071 blacks and 357,494 whites).
The demographic patient characteristics (age, gender, and annual income), CHD risk factors, cardiac medications, cardiac outcome (angina, AMI, and CABG) are listed in Table 1 . Black patients were younger (by 6.5 years) and had a lower income than did white patients. The black patients had a lower body mass index and a lower incidence of depression than the white patients. As expected, the black patients had greater rates of hypertension than the white patients. Before adjustment for covariates, the crude rates of prescriptions for β blockers, statins, and ACE inhibitors were significantly lower among blacks than among whites, but the prescription rates for aspirin were similar in the 2 groups. Cardiac events such as angina and AMI occurred more often in blacks than in whites. The black patients had also undergone CABG less often than had the white patients.
| Variable | Whites (n = 357,494) | Blacks (n = 117,071) | p Value |
|---|---|---|---|
| Age (years) | 65.1 ± 13.8 | 58.1 ± 14.8 | <0.0001 |
| Men | 96.4% | 94.3% | <0.0001 |
| Income ($1,000/year) | 19.7 ± 19.9 | 15.2 ± 17.2 | <0.0001 |
| Body mass index (kg/m 2 ) | 28.5 ± 5.6 | 28.1 ± 5.8 | <0.0001 |
| Total cholesterol (mg/dl) | 195 ± 42.1 | 194.7 ± 43 | 0.1312 ⁎ |
| Diabetes mellitus | 17.5% | 16.9% | <0.0001 |
| Hypertension | 43.7% | 44.5% | <0.0001 |
| Depression | 14.5% | 14.2% | 0.0031 |
| Angina pectoris | 5.8% | 6.7% | <0.0001 |
| Acute myocardial infarction | 0.92% | 0.94% | 0.5489 |
| Coronary bypass | 1.21% | 0.4% | <0.0001 |
| β Blockers | 24.8% | 19.7% | <0.0001 |
| Statins | 30.2% | 20.5% | <0.0001 |
| Angiotensin-converting enzyme inhibitors | 30% | 27.7% | <0.0001 |
Next, we adjusted the rates for the prescription of cardiac medications, cardiac events, and CABG for all variables mentioned in the analysis section. The data ( Table 2 ) showed that the odds of blacks receiving prescriptions for β blockers, statins, and ACE inhibitors were 26%, 46%, and 6% lower than for whites (all p <0.0001); however, but the odds of receiving a prescription for aspirin were 31% greater than that for whites (p <0.001). Black patients had a risk of experiencing angina and AMI that was 38% and 11% greater than for white patients (p <0.0001 and p <0.006, respectively). Finally, the risk of black patients undergoing CABG was 56% lower than that of white patients (p <0.0001). The differences in the prescription of cardioprotective drugs, cardiac events, and CABG rates between blacks and whites are shown in Figure 1 .
| Variable | Adjusted OR (Blacks vs Whites) | 95% CI | p Value |
|---|---|---|---|
| Aspirin | 1.31 | 1.27–1.35 | <0.0001 |
| β Blockers | 0.74 | 0.72–0.75 | <0.0001 |
| Statins | 0.54 | 0.52–0.55 | <0.0001 |
| Angiotensin-converting enzyme inhibitors | 0.94 | 0.92–0.96 | <0.0001 |
| Angina pectoris | 1.38 | 1.34–1.42 | <0.0001 |
| Acute myocardial infarction | 1.11 | 1.03–1.19 | 0.0061 |
| Coronary artery bypass grafting | 0.44 | 0.4–0.48 | <0.0001 |
The odds of receiving a prescription for aspirin, β blockers, statins, and ACE inhibitors increased with patient age. Increases in income, or a greater income, were associated with greater odds of statin prescriptions. In contrast, it was just the opposite for prescriptions of aspirin, β blockers, and ACE inhibitors ( Table 3 ). The odds of receiving a prescription for aspirin, β blockers, statins, and ACE inhibitors increased with the diagnosis of angina or AMI or with the use of CABG (all p <0.001). Furthermore, the odds of prescriptions for aspirin, statins, and ACE inhibitors increased, but that for β blockers decreased, with the diagnosis of diabetes (p <0.001). The prescriptions for aspirin were positively associated with patients receiving the other 3 drugs. This pattern was observed with each cardioprotective drug ( Table 3 ), suggesting that physicians tended to prescribe combinations of these 4 drugs to their patients.
| Variable | Aspirin Use | β Blocker Use | Statin Use | Angiotensin-Converting Enzyme Inhibitor Use | ||||
|---|---|---|---|---|---|---|---|---|
| OR | 95% CI | OR | 95% CI | OR | 95% CI | OR | 95% CI | |
| Race | 1.31 | 1.27–1.35 | 0.74 | 0.72–0.75 | 0.54 | 0.52–0.55 | 0.94 | 0.92–0.96 |
| Age (5 years) | 1.13 | 1.12–13 | 1.02 | 1.01–1.02 | 1.02 | 1.01–1.02 | 1.05 | 1.04–1.05 |
| Income | 0.90 | 0.89–0.91 | 0.99 | 0.98–0.99 | 1.12 | 1.11–1.12 | 0.99 | 0.99–0.99 |
| Acute myocardial infarction | 4.5 | 3.95–5.13 | 4.55 | 4.15–4.99 | 1.51 | 1.35–1.68 | 2.18 | 1.99–2.38 |
| Angina | 3.58 | 3.42–3.74 | 2.98 | 2.88–3.07 | 1.69 | 1.62–1.77 | 1.25 | 1.21–1.29 |
| Coronary artery bypass grafting | 1.56 | 1.41–1.72 | 3.39 | 3.13–3.67 | 3.14 | 2.79–3.52 | 1.34 | 1.24–1.44 |
| Depression | 1.44 | 1.39–1.48 | 1.24 | 1.21–1.26 | 1.4 | 1.36–1.44 | 0.99 | 0.97–1.02 |
| Diabetes | 1.37 | 1.34–1.42 | 0.91 | 0.9–0.93 | 2.11 | 2.06–2.17 | 4.54 | 4.44–4.63 |
| Hypertension | 2.04 | 1.98–2.11 | 4.76 | 4.66–4.86 | 3.26 | 3.17–3.35 | 9.31 | 9.11–9.51 |
| Smoker | 1.97 | 1.88–2.07 | 1.17 | 1.13–1.21 | 1.36 | 1.29–1.42 | 0.94 | 0.91–0.98 |
| Aspirin | 2.49 | 2.44–2.53 | 2.22 | 2.16–2.27 | 1.85 | 1.82–1.89 | ||
| β Blockers | 2.44 | 2.38–2.51 | 2.36 | 2.29–2.42 | 1.73 | 1.7–1.77 | ||
| Statins | 2.24 | 2.18–2.3 | 2.39 | 2.34–2.43 | 1.98 | 1.94–2.01 | ||
| Angiotensin-converting enzyme inhibitors | 1.89 | 1.84–1.95 | 1.76 | 1.73–1.8 | 1.99 | 1.94–2.04 | ||
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