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(Hypertension. 2008;51:1149.)
© 2008 American Heart Association, Inc.
Go Red Original Articles |
From the Geriatrics Research, Education, and Clinical Center (S.K.), James J. Peters Veterans Administration Medical Center, Bronx, NY; Departments of Health Policy (S.K., P.L.H., M.A.M.), Medicine (J.V.S., M.A.M.), Geriatrics and Adult Development (M.A.M.), and General Internal Medicine (S.K.), Mount Sinai School of Medicine, New York, NY.
Correspondence to Salomeh Keyhani, Department of Health Policy, Mount Sinai School of Medicine, Box 1077, 1 Gustave L. Levy Place, New York, NY 10029. E-mail salomeh.keyhani{at}mountsinai.org
| Abstract |
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Key Words: womens health quality of health care hypertension chronic disease ambulatory care
| Introduction |
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1 million deaths caused by CVD in the United States.2 Despite the substantial risk of developing or dying from coronary heart disease and stroke in women, studies reveal that women with CVD or CVD risk factors are less likely than men to receive recommended preventive therapies.3–11 In addition, although hypertension significantly increases the risk for cardiovascular events, such as myocardial infarction, heart failure, and stroke, and has been increasing in prevalence, the most recent national survey suggests that the percentage of women treated has largely remained unchanged.2,12,13
In 2003, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure guidelines defined a new prehypertension category with the purpose of motivating physicians to treat blood pressure more aggressively.14 In addition, the first set of evidence-based guidelines for prevention of CVD in women were published in 2004 as a result of a collaborative effort by many organizations, including the American Heart Association, the American College of Cardiology, American Medical Womens Association, and the American College of Obstetrics and Gynecology.15 Whether the dissemination of these guidelines had an impact on reduction in gender-based disparities of cardiovascular care is unknown.
The purpose of this study was to provide a national estimate of gender-based disparities in blood pressure control and cardiovascular care, which is defined as receipt of recommended treatment for ischemic heart disease, cerebrovascular disease, and diabetes. We also explored whether treatment inertia may explain gender differences in blood pressure control. We contributed to the literature on gender disparities in cardiovascular care at ambulatory visits by providing the most recent estimates from national surveys.
| Materials and Methods |
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Dependent Variables
Three separate sets of dependent variables were defined: (1) blood pressure control; (2) use of any antihypertensive medication or initiation of new therapy for patients with uncontrolled hypertension; and (3) appropriate therapy for select cardiovascular conditions. Blood pressure control (systolic and diastolic) was categorized dichotomously as controlled or uncontrolled. For patients with hypertension, control was defined as systolic blood pressure <140 mm Hg and diastolic blood pressure <90 mm Hg. For patients with diabetes, control was defined as systolic blood pressure <130 mm Hg and diastolic blood pressure <80 mm Hg. Patients were classified as having hypertension if their primary care provider responded positively to the NAMCS survey question querying the presence of this condition. For those patients with hypertension, an indicator variable was created to represent whether blood pressure at that visit was uncontrolled (>140/90 mm Hg) or severely uncontrolled (>150/95 mm Hg). An indicator variable was also created for receipt of an antihypertensive medication (any diuretic, β-blocker, calcium channel blocker, angiotensin-converting enzyme inhibitor [ACEI], angiotensin receptor blocker [ARB], hydralazine, minoxidil, or clonidine). All of the other dependent variables were dichotomous indicators for the use of a recommended therapy. Receipt of aspirin for ischemic heart disease or cerebrovascular disease, a β-blocker for ischemic heart disease, an ACEI or ARB for diabetic patients with hypertension, and a statin for patients with diabetes or ischemic heart disease was considered recommended therapy.
Independent Variables
Because past research has documented that older women had poorer blood pressure control compared with men,13 we divided the sample into 3 age categories (18 to 64, 65 to 80, and >80 years). Because there were only 164 patients under the age of 35 years with hypertension, we did not divide the 18- to 64-year age group into smaller categories. Indicator variables were created for race (black, white, or other), ethnicity (Hispanic or non-Hispanic), insurance status (Medicare, Medicaid, or private insurance), and the presence of hypertension, diabetes, CVD, congestive heart failure, hyperlipidemia, ischemic heart disease, and obesity. A measure of disease severity was developed if the patient had
5 chronic conditions listed in response to the 14 NAMCS physician survey questions on chronic conditions for each visit. Data on patients smoking status and the survey (NAMCS or NHAMCS) from which the visit was drawn were included as covariates in the analysis. Data on the number of visits in the past year were also included.
Statistical Analysis
The association between gender and each of the dependent variables was examined. Univariable relationships were tested using
2 statistics, and multivariable logistic regression models were estimated that controlled for age, race, ethnicity, insurance, comorbid conditions, severity of illness (>5 chronic conditions), and survey (NAMCS or NHAMCS). The comorbid conditions listed in Table 1 were included in the models, because these variables were hypothesized to be related to blood pressure control or secondary prevention. In a sensitivity analysis, we examined whether the results were robust to exclusion of comorbid conditions from the models focusing on receipt of recommended therapy. The differences in the number and class of antihypertensive medications by gender using
2 and nonparametric statistics (Kruskal-Wallis test) were examined.
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Visits with missing blood pressure data (<3.2%) in the sample were excluded from the analyses. There were no missing data for other outcomes. As recommended by the National Center for Health Statistics,16,17 estimates with >30% SEs or <30 cases were excluded because they may be unreliable. All of the analyses took into account the complex NAMCS and NHAMCS survey designs and sampling weights and were performed using Stata statistical software, version 9.2 (Stata Corp).
| Results |
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3 visits with their primary care provider in the past year (81% versus 74%; P<0.05).
Gender and Blood Pressure Control
Hypertension was identified by physicians in 4435 visits (Table 2). Women were less likely than men to have controlled hypertension (54.0% versus 58.7%; P<0.02). There was no difference in the rate of severely uncontrolled hypertension (defined as >150/90 mm Hg) by gender among patients with hypertension or diabetes (7.8% versus 7.4%; P=0.74). Among visits with patients aged 65 to 80 years, women were less likely than men to have controlled hypertension (53.4% versus 63.2%; P<0.005; Table 3). In multivariable models this relationship persisted, and women in this age group were also less likely than men to have controlled blood pressure (odds ratio: 0.62; 95% CI: 0.45 to 0.85). Among diabetic subjects, women were less likely to have controlled blood pressure in all of the age groups; however, these relationships were not statistically significant.
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Gender Disparities in Medication Use and Initiation of Therapy
The median number of antihypertensive medications in men and women was 1 and ranged from 1 to 5 (interquartile range: 0 to 2). There was no statistically significant difference in the number of medications used by gender (P=0.07). Women less commonly received an ACEI (20.9% versus 28.7%; P<0.001) and more commonly received diuretics (20.9% versus 16.9%; P=0.05) in the treatment of hypertension (Figure). No statistically significant relationships were identified between gender and use of any antihypertensive medication in patients with uncontrolled hypertension (odds ratio: 0.77; 95% CI: 0.43 to 1.39) or initiating a new blood pressure medication among patients with uncontrolled hypertension who were already receiving therapy (odds ratio: 1.28; 95% CI: 0.66 to 2.46; Table 4).
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Quality of Care for Select Chronic Conditions
Ischemic heart disease and/or cerebrovascular disease were identified in 788 patients. A total of 605 patients had ischemic heart disease, 1228 patents had both diabetes and hypertension, and 2342 patients had either diabetes or ischemic heart disease (Table 5). Less than half (20.7% to 46.6%) of all of the patients received recommended therapy across all of the conditions considered. Women were less likely than men to receive an aspirin (20.7% versus 35.5%; P<0.001), a β-blocker (31.9% versus 44.5%; P<0.05), or a statin (28.5% versus 35.3%; P<0.05) among conditions where these treatments are recommended. In multivariable analyses, women with ischemic heart disease and cerebrovascular disease were less likely than men to receive an aspirin (odds ratio: 0.43; 95% CI: 0.27 to 0.67), and women with ischemic heart disease were less likely than men to receive a β-blocker (odds ratio: 0.60; 95% CI: 0.36 to 0.99). Sensitivity analyses demonstrated that exclusion of comorbid conditions from the models did not significantly change the relationship between gender and receipt of recommended therapies (data not shown).
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| Discussion |
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During the most recent National Health and Nutrition Examination Survey period, 1999–2004, hypertension prevalence increased among women, especially older women (>70 years); however, there was no significant change in hypertension control for women as seen in men from the previous survey period (1988–1994).13 Also, older women (aged 70 to 79 years) had significantly decreased blood pressure control rates compared with younger women, despite being equally likely to be treated. Our study further demonstrates that older women (aged 65 to 80 years) are less likely to have their blood pressure controlled than men. Given that women have more clinician visits per year than men, these persistent disparities are all the more troubling.
Despite the substantial risk of coronary heart disease and stroke in women, women with CVD or risk factors are less likely than men to receive recommended preventive therapies. There has been less frequent use of established treatments for primary and secondary prevention, including β-blockers,4,7,9 aspirin,4,6,10 and lipid-lowering therapies5,8,10 in women compared with men. This is even seen in women known to be at high-risk for CVD, such as diabetic subjects11 or those diagnosed with coronary artery3,4,9 and cerebrovascular disease.6 Our study confirms significantly less aspirin use in women with known CVD compared with men. Although the prevalence of aspirin use has increased since the 1990s, aspirin is still significantly underused as secondary prevention for CVD.18,19 A potential explanation for the lower use of aspirin could be misconceptions regarding the degree of CVD risk in women. We also found lower use of β-blockers in women with ischemic heart disease. This may be a function of the older age of women with ischemic heart disease or lack of awareness and adherence to CVD prevention guidelines.7 We did not find a statistically significant difference in statin or ACEI/ARB use as a function of gender for patients with diabetes and ischemic heart disease. This may reflect improved use of these medications in the secondary prevention of CVD in women.20 However, in this study women were still less likely to receive ACEI for the treatment of hypertension than men. These findings are in line with recently published analyses of patients at risk for cardiovascular events.21,22 The reason for this disparity is unclear and warrants further investigation.
Why do gender disparities in the control of CVD persist? Although awareness of the magnitude and impact of CVD and the treatment of CVD risk factors is improving in women,23–26 there is still insufficient recognition, diagnosis, and treatment.25,27 Many women underestimate their risk for developing heart disease and stroke. A 2003 American Heart Association survey found that only 13% of US women perceived CVD as their greatest threat, an increase from 7% in 1997.23 Clinicians also contribute to the lack of recognition and less aggressive management of cardiovascular risk in women. As recently as 2004, <20% of physicians were aware that women are more likely than men to die of heart disease.2 Awareness of national heart disease prevention guidelines also does not necessarily translate to improved clinical practice.27,28 In addition, physicians have the misconception that the risk of heart disease is less important in women than in men.3,27
Several studies have assessed reasons for uncontrolled hypertension in both men and women. Berlowitz et al29 found that physicians made no change to medications on 75% of visits. Previous investigators have suggested that physician satisfaction with an elevated blood pressure contributes to a failure to make medication changes when blood pressure is elevated.30,31 Clinical inertia is a recognized barrier to effective care and was hypothesized in this study as a possible reason for persistent gender disparities in blood pressure control.32 No significant differences in the use of any blood pressure medication or initiation of new therapy for patients with uncontrolled hypertension as a function of gender were found. Given the high prevalence of uncontrolled hypertension in women, further analysis regarding the gender-based differences in blood pressure treatment are necessary.
Limitations
This analysis has several limitations that deserve comment. The findings are limited by the cross-sectional nature of the data and small sample sizes for each disease and specific analysis. Our sample of men and women over age 80 years with hypertension and diabetes is relatively small, which limits the interpretation of the results in this age group. In addition, the rates of aspirin use for secondary prevention of CVD are lower than reported previously in hospital-based and outpatient studies.4,33,34 Perhaps ambulatory care physicians are less likely to document the use of an aspirin because it is an over-the-counter medication. However, there is no reason to believe there may be differential documentation of aspirin use by gender. Another limitation is that this is a visit-based analysis and we only have 1 blood pressure recording per patient; however, across the entire sample, it would be reasonable to assume that outliers for each patient are distributed equally by gender. Furthermore, no information was available on the accuracy of blood pressure measurements. However, the blood pressure readings recorded in NAMCS and NHAMCS are a representation of present primary care practice and are the basis for treatment decisions. Furthermore, in the analyses of treatment inertia, we do not know whether a physician doubled a medication dose and only have information on whether a new prescription was written. Finally, we had no data on income, education, adherence, patient preferences regarding treatment, or physician characteristics. The gender differences that we identified could be related to these omitted variables.
Perspectives
Cardiovascular mortality has declined over the past 3 decades among men and women, but the rate of decline is less among women.26,35 The overall decline in CVD deaths has largely been attributed to cardiovascular risk factor reduction, as well as to the use of evidence-based medical treatments for secondary prevention. The persistent gender disparities in the treatment of CVD and control of modifiable risk factors will continue to increase the risk of CVD among women and adversely affect the prognosis of women with CVD. Our study highlights the need for increased awareness of the persistent gender disparities in CVD management and also reveals the inadequate delivery of cardiovascular care to all patients. This study illustrates the continued need for quality improvement efforts among physicians and policy makers for all patients.
| Acknowledgments |
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Sources of Funding
This project was not directly supported by any external grants or funds. S.K. is currently supported by Department of Veterans Affairs Health Services Research and Development Service project No. TRP-02-149 and a VA HSR&D Career Development Award. M.A.M. is supported in part by the National Institutes of Health Centers of Excellence in Partnerships for Community Outreach, Research on Health Disparities and Training (Project EXPORT).
Disclosures
None.
Received December 2, 2007; first decision December 21, 2007; accepted January 25, 2008.
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