Ethnic Differences in Blood Pressure Control Among Men at Veterans Affairs Clinics and Other Health Care Sites

Background  Differential access to health care may contribute to lower blood pressure (BP) control rates to under 140/90 mm Hg in African American compared with white hypertensive patients, especially men (26.5% vs 36.5% of all hypertensive patients in the National Health and Nutrition Examination Survey 1999-2000). The Department of Veterans Affairs (VA) system, which provides access to health care and medications across ethnic and economic boundaries, may reduce disparities in BP control.

Methods  To test this hypothesis, BP treatment and control groups were compared between African American (VA, n = 4379; non-VA, n = 2754) and white (VA, n = 7987; non-VA, n = 4980) hypertensive men.

Results  In both groups, whites were older than African Americans (P<.05), had lower BP (P<.001), and had BP controlled to below 140/90 mm Hg more often on their last visit (P<.01). Blood pressure control to below 140/90 mm Hg was comparable among white hypertensive men at VA (55.6%) and non-VA (54.2%) settings (P = .12). In contrast, BP control was higher among African American hypertensive men at VA (49.4%) compared with non-VA (44.0%) settings (P<.01), even after controlling for age, numerous comorbid conditions, and rural-urban classification. African American hypertensive men received a comparable number of prescriptions for BP medications at VA sites (P = .18) and more prescriptions at non-VA sites than did whites (P<.001). African Americans had more visits in the previous year at VA sites (P<.001) and fewer visits at non-VA sites (P<.001) compared with whites.

Conclusions  The ethnic disparity in BP control between African Americans and whites was approximately 40% less at VA than at non-VA health care sites (6.2% vs 10.2%; P<.01). Ensuring access to health care could constitute one constructive component of a national initiative to reduce ethnic disparities in BP control and cardiovascular risk.

In the National Health and Nutrition Examination Survey (NHANES) 1999-2000, African Americans had a higher prevalence of hypertension compared with whites.¹ Hypertension is a major contributor to excess cardiovascular and renal morbidity and mortality in African Americans than in whites.^2,3 Disparities in cardiovascular risk factor control and outcomes are striking for African American men.^4-11 The NHANES 1999-2000 indicated that blood pressure (BP) control to below 140/90 mm Hg was achieved in only 26.5% of African American men and 36.5% of white men with hypertension. In contrast, hypertension control rates were comparable in African American and white women at 29.4% vs 30.5% of all hypertensive women.¹

The explanation for the persisting ethnic differences in hypertension control and in cardiovascular and renal outcomes is not fully known but may include biological, cultural, social, health care provider, and health care system factors, such as insurance and access to care and medications. Other reports indicate that greater access to care and medications does not ensure better hypertension control.^12,13 These observations raise the possibility that other factors may predominate.¹⁴ An accurate assessment of variables contributing to health disparities is essential in allocating resources to support effective solutions.

In the present study, primary care practice data were examined to assess the treatment and control of hypertension in African American and white hypertensive patients at Department of Veterans Affairs (VA) and non-VA health care sites. The analysis focused on men because ethnic differences in hypertension control are more evident in men.¹ Moreover, men comprised approximately 97% of patients in the VA Hospital and Clinic system.

Access to health care services and formulary medications in the VA system is without inherent ethnic or economic bias. Thus, ethnic differences in BP control at the VA are likely to reflect factors other than access to care and medications. Moreover, by comparing ethnic differences in hypertension control among patients at VA and non-VA sites, the impact of universal access to care and medications on ethnic disparities in BP control can be estimated.

This study was reviewed and approved by the Office of Research Protection and Integrity at the Medical University of South Carolina and the Research and Development Committee at the Ralph H. Johnson VA Medical Center, Charleston. Men receiving care for hypertension during the years 2001 through 2003 at the VA Medical Center and affiliated VA community-based outpatient clinics as well as from non-VA sites were included. Data from non-VA facilities were derived from the Hypertension Initiative.¹⁵

A computerized patient record system was searched for eligible patients for the VA. The data from non-VA sites were obtained from either electronic medical records or from data cards completed at the time of clinic visits for hypertensive patients.¹⁵ The conduct of this study was compliant with the Health Insurance Portability and Accountability Act.

Information obtained from the medical record included patient demographics, dates of medical visits, BP, and antihypertensive medications at each visit from January 2001 through December 2003.

The principal criterion for determining the presence of hypertension was based on the diagnostic problem list for each patient. The patient was also designated as hypertensive if a systolic BP (SBP) above 140 mm Hg and/or a diastolic BP (DBP) above 90 mm Hg were recorded on 3 or more consecutive visits in the past year or if the patient was prescribed antihypertensive medications without another diagnostic indication evident.

The major categories of antihypertensive medications were α₁-receptor blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-receptor and α,β-receptor blockers, dihydropyridine calcium channel blocker, nondihydropyridine calcium channel blocker, diuretics, and other (vasodilators, central sympatholytics, and ganglionic blockers).

The BP recorded on the most recent clinical visit during the study period was used to determine hypertension control. Blood pressure was defined as controlled when the most recent clinic readings for both SBP and DBP were below 140/90 mm Hg. Blood pressure was defined as partially controlled when the higher of the SBP and/or DBP was 140 to 149/90 to 94 mm Hg at the most recent visit. Blood pressure was designated as uncontrolled when the SBP and/or DBP was above 150/95 mm Hg at the last clinic encounter.

Patients were classified according to the Rural/Urban Code Assignment (RUCA) classification system developed by the University of Washington’s Rural Health Research Center. This classification addresses limitations in accurately assigning an urban or rural designation to geographic locations.¹⁶

Data are reported as mean ± SD for descriptive purposes and as mean ± SEM when mean values for African Americans and whites are compared. When appropriate, data are reported as percentages. Ethnic differences in hypertension treatment and control between African American and white men were examined using χ² tests. Data in these 2 ethnic groups were further analyzed controlling for age and sex using the Cochran-Mantel-Haenszel method. Multivariable logistic regression was used to compare differences in BP control rates between VA and non-VA patients adjusting for covariates (eg, age, ethnicity, body mass index [BMI], RUCA code, and comorbid diagnoses including diabetes, lipid disorders, cardiovascular disease, chronic heart failure, and renal disease). Because ethnicity was a determinant of differences in BP control between VA and non-VA sites, the multivariable logistic regression analysis was performed separately for whites and African Americans. Statistical Analysis Software version 9.01 (SAS Institute Inc, Cary, NC) was used for all data analysis. P values <.05 were accepted as statistically significant.

The average BP for all VA patients was 138.3/77.2 mm Hg ± 0.2/0.1 mm Hg, and 53% of hypertensive patients achieved the goal BP of below 140/90 mm Hg (Table 1). Among hypertensive men, whites were older than African American (Table 2). Compared with African Americans, whites had lower BP (Table 2) and were more likely to have BP controlled at the last visit (Figure 1A). Approximately 20% of white and African American hypertensive men had BP within 10/5 mm Hg of goal (ie, <150/95 mm Hg but ≥140/90 mm Hg [Table 1 and Figure 2A]).

African American and white men undergoing treatment received a similar number of prescriptions for antihypertensive medications at the VA sites (1.76 ± 0.02 vs 1.73 ± 0.01; P = .18). Compared with whites, African Americans received more diuretics and calcium channel blockers; comparable angiotensin-converting enzyme inhibitors, α-blockers (not shown), α,β-blockers (not shown), and angiotensin receptor blockers; and fewer β-blockers (Table 3). African Americans had more clinic visits compared with whites in the previous year (4.53 ± 0.05 vs 4.12 ± 0.03; P<.001).

Overall the average BP for all non-VA patients was 136.4/80.4 ± 0.2/0.1 mm Hg, and 51% of hypertensive patients achieved the goal BP of below 140/90 mm Hg (Table 1). Compared with African American hypertensive men, white hypertensive men were older, had lower BP (Table 2), and had BP controlled to below 140/90 mm Hg more often on their last visit (Figure 1A). Twenty-two percent of white and African American hypertensive men had BP within 10/5 mm Hg of goal (ie, <150/95 mm Hg but ≥140/90 [Table 1 and Figure 2A]).

Compared with whites, African Americans undergoing treatment received on average more prescriptions for diuretics, calcium channel blockers, angiotensin-converting enzyme inhibitors, α-blockers, α,β-blockers, and angiotensin receptor blockers, and they received fewer β-blockers (Table 2) and more total antihypertensive prescriptions (2.36 ± 0.03 vs 2.08 ± 0.02; P<.001). African Americans had fewer clinic visits than whites in the previous year (2.80 ± 0.02 vs 3.67 ± 0.02; P<.001).

Hypertensive patients at the VA were, on average, approximately 6 years older and had higher SBP and lower DBP compared with non-VA patients in both ethnic groups (Table 1). Despite the older age of VA patients, BP control to below 140/90 mm Hg was similar in white (P = .12) and higher in African American hypertensive patients (P<.005) seen at VA than at non-VA sites (Figure 1B). In whites, the BP goal of below 140/90 mm Hg was achieved in 55.6% of the VA and 54.2% of the non-VA group (P = .12). However, among African American men, BP control to below 140/90 mm Hg was obtained more often in the VA than in the non-VA patients (49.4% vs 44.0%; P<.005) as shown in Figure 1B. In both VA and non-VA settings, the lower rate of BP control in African Americans compared with whites did not reflect a less intensive therapeutic effort defined by the mean number of antihypertensive medications recorded in the medical record. The frequency of visits was greater for African American than for white men in the VA group but lower for African American than for white men at non-VA sites. The ethnic difference in the percentage of white and African American hypertensive men with BP controlled to below 140/90 mm Hg was smaller in VA clinics than in non-VA clinics but remained significant (Figure 1C).

Because multivariable logistic regression analysis indicated that ethnicity and age were significant determinants of differences in BP control between VA and non-VA sites, the multivariable logistic regression analysis was repeated separately for African Americans and whites. The results of multivariable logistic regression analysis for African Americans showed that BP control remained significantly lower for those seen at non-VA compared with VA sites (odds ratio, 0.839; 95% confidence interval, 0.742-0.949) after controlling for age, BMI, the presence of comorbid disorders of lipid and glucose metabolism, cardiovascular disease, heart failure, nephropathy, and RUCA code (Table 4). In other words, African American hypertensive men seen outside the VA were 16.1% (95% confidence interval, 5.1%-25.8%) less likely to have their BP controlled to below 140/90 mm Hg. The same analysis for whites did not reveal a significant difference in control rates between VA and non-VA sites (data not shown). The presence of cardiovascular disease and heart failure resulted in significantly higher BP control rates, whereas older age, higher BMI, and history of nephropathy were associated with lower BP control rates.

Figure 2A-B compares the BP control of below 150/95 mm Hg in VA and non-VA sites between white and African American men. Figure 2C shows the ethnic disparity in BP controlled to below 150/95 mm Hg at VA and non-VA sites.

Matched to the 2000 census information, whites had higher income and education status compared with African Americans in each of the RUCA codes. However, there were no significant differences between African American and white hypertensive men at the VA and their race-matched counterparts seen at non-VA sites in median household income (1999 dollars) and the percentages with a high school education or more. Veterans Affairs patients were more likely to originate from the combination of “small rural” and “isolated small rural” zip codes than were men receiving care at non-VA sites (25.1% [VA] vs 13.7% [non-VA]; P<.05). Therefore, RUCA code was included in the multivariable logistic regression analysis comparing BP control at VA and non-VA sites. By RUCA code classification, urban and large rural areas were more likely to have BP in control compared with isolated rural areas.

Blood pressure control among African American hypertensive men was higher for those seen at VA compared with non-VA health care sites. Moreover, the differences in BP control between white and African American men were less at VA than at non-VA health care locations. Blood pressure was controlled to below 140/90 mm Hg in 49.4% of African Americans at the VA and 44.0% of African Americans at non-VA sites. In contrast, BP control among white men was similar at both sites. These results suggest that site of care has greater impact on health care, specifically BP control, in African Americans than in whites.

The lower BP control rate among African Americans at VA compared with non-VA sites was not explained by differences in age, level of education, median household income, or residency in urban or rural locations. In fact, more VA patients were living in the small rural and isolated areas compared with the non-VA patients. Because health care status and outcomes tend to be poorer for rural than for urban areas,¹⁷ the observed difference in RUCA code distribution may highlight relative advantages of the VA system in controlling BP.

The better BP control rate among African Americans receiving care at VA compared with non-VA clinics was also not explained by differences in the number of antihypertensive medications (Table 3). African American and white hypertensive men received a similar number of prescriptions for BP medications at VA sites, whereas African American men received more antihypertensive medications at non-VA sites. It could be postulated that poorer hypertension control rates in African Americans should have elicited an even more intensive therapeutic effort than in whites.

The database did not include information on prescriptions filled. The ratio of prescriptions filled to written may have differed by ethnicity and clinic setting. For example, the higher cost of medications for non-VA patients may have contributed to a lower ratio of prescriptions filled to written, leading to even more prescriptions written in an attempt to control BP. By extension, greater financial limitations of African Americans compared with whites could lead to an even lower ratio of prescriptions filled, which may contribute to more prescriptions being written for African American than for white hypertensive patients outside the VA. The data and considerations noted raise the possibility that better access to medications may have contributed to the smaller ethnic difference in BP control at VA compared with non-VA sites.

Compared with whites, African Americans had a greater number of visits per year in the VA sites but fewer documented visits at non-VA sites, suggesting that a higher visit frequency may contribute to better BP control for African American men seen at VA sites. Better access to health care for African American men at VA compared with non-VA sites, as assessed by the number of visits relative to whites seen at the same locations, may have contributed to a smaller ethnic difference in BP control at the VA. Compared with whites, ethnic minorities are less likely to have health insurance,¹⁸ are more likely to have publicly funded health insurance (eg, Medicaid), and even when insured equally, may face additional economic barriers to care, including high copayments and geographic barriers (eg, a relative scarcity of health care providers and health care facilities in minority communities and insufficient transportation). These access-related factors are likely the most significant barriers to equitable care.¹⁹

On the other hand, other evidence suggests that disparities of insurance and income account for some but probably not most ethnic disparities in health care utilization.^20-24 Weinick et al¹⁴ have shown that disparities in insurance and income account for approximately 23% to 45% of the ethnic differences in access to care and utilization of health care services. In an attempt to elucidate the confounding variables that could explain these differences, additional analysis were performed. In multivariable logistic regression analysis, controlling for age, BMI, RUCA code, and multiple comorbid conditions, ethnicity was a significant determinant of the difference in BP control at VA compared with non-VA sites (data not shown).

Our findings suggest that the VA system offers advantages in controlling hypertension, especially in African Americans. The VA has a long history of leadership in the treatment of hypertension. The earliest multicenter trials demonstrating the benefit of antihypertensive treatment were conducted in the VA health system.^25,26 In response to reports of suboptimal BP control in VA patients,¹² the VA developed special programs to improve hypertension control.^27,28 It may be instructive to assess the potential impact of these efforts on variables such as visit frequency that could favorably impact BP control,²⁹ particularly among African Americans.

Another potentially important finding in our study was that about 20% of hypertensive men had a BP below 150/95 mm Hg but 140/90 mm Hg or above in all groups, indicating that they were near the goal of below 140/90 mm Hg (Figure 2). This is consistent with other reports on uncontrolled hypertensive patients³⁰ and suggests that modest improvements in BP control for those near the goal of below 140/90 mm Hg could dramatically improve overall control rates to approximately 75% for white men and 65% to 70% for African American men.

The earlier onset, higher prevalence, and greater severity of hypertension coupled with undiagnosed, untreated, and inadequately treated hypertension result in a substantially greater burden of stroke, heart, and end-stage renal disease and a decreased life expectancy in African Americans than in whites.^2,10,31-33 Improving hypertension treatment and control has a beneficial impact on cardiovascular outcomes in African Americans and whites, with greater relative benefits in the former.^11,34 Although hypertension control rates have improved in the last 3 decades, the rates remain unacceptably low, especially in ethnic minorities.^1,3

The analysis was limited to medical practices mainly in South Carolina and may not be representative of health care, especially outside the Southeast. However, hypertension control rates in our study are comparable to values reported for aware and treated hypertensive patients in the NHANES 1999-2000 survey. Data for all patients receiving health care at the VA were obtained from a common electronic medical record system, whereas data for non-VA hypertensive patients were obtained from various electronic systems and paper reporting.¹⁵ Thus, data on the number of medications and visits, in particular, may not be directly comparable for VA and non-VA hypertensive patients. Nevertheless, a comparison of relative ethnic differences at VA and non-VA sites on variables including visit frequency and number of antihypertensive medications prescribed should not be significantly affected. Ethnicity data were missing in approximately one fourth of patients at VA and non-VA sites. Prescription (re)fill rates were not assessed for either model of care and may have revealed ethnic differences, especially at the non-VA sites for reasons discussed earlier.

The percentage of African American men with controlled hypertension was greater at VA than at non-VA clinics (49.4% vs 44.0%; P<.001), whereas BP control among white men was not significantly different at the 2 sites. The ethnic difference in BP control at the VA was approximately 40% less than at non-VA sites (6.2% vs 10.2%, P<.001). The ethnic difference in BP control between VA and non-VA sites was not diminished in multivariable logistic regression analysis controlling for age, BMI, cardiovascular and renal diseases, and RUCA classification. In fact, these analyses suggest that the ethnic disparity in BP control between VA and non-VA sites would have been even greater if the confounding variables had been equally distributed. Our data raise the possibility that better access to care, assessed by visit frequency, and possibly better access to medications may contribute to the VA advantage for controlling BP in African Americans. While it will be important to identify and quantify the factors explaining better BP control for African Americans at the VA, these data suggest that ensuring access to health care could constitute a constructive national response to reducing ethnic disparities in BP control and cardiovascular outcomes.

Correspondence: Shakaib U. Rehman, MD, Ralph H. Johnson Veterans Affairs Hospital, 109 Bee St (11C), Charleston, SC 29401 (shakaib.rehman@med.va.gov).

Accepted for Publication: January 5, 2004.

Financial Disclosure: None.

Funding/Support: This work was supported in part by the Department of Veterans Affairs Research Service (Drs Rehman and Hutchison) and grants P01HS1087 (EXCEED) from the Agency for Healthcare, Research, and Quality, Rockville, Md; the Duke Foundation, Charlotte, NC; grants HL04290, HL58794, and P60-MD00267 (EXPORT) from the National Heart, Lung, and Blood Institute, Bethesda, Md; the Department of Health and Human Services (Stroke Belt Elimination Initiative), Washington, DC; and the South Carolina Department of Health and Environmental Control, Columbia.