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Home > RNJ > 2008 > July/August > A Comparison of Stroke Risk Factors in Women With and Without Disabling Conditions

A Comparison of Stroke Risk Factors in Women With and Without Disabling Conditions
Janice L. Hinkle, PhD RN CNRN Rosalind Smith, RN Karen Revere

Many adults with disabilities reside in the United States, but whether women with and without disabling conditions differ in terms of stroke risk factors and treatment response is unknown. This descriptive study was designed to determine whether women with and without disabling conditions have different demographic characteristics, self-reported rates of stroke risk factors, and blood pressure readings on the day of screening. Data were collected at a variety of conferences and meetings convened to address health care for women and people with disabilities. Among the 204 participants, 62% (n = 126) had a disabling condition and 38% (n = 78) had no disability. The primary instrument used to measure the differences among women with and without disabling conditions in this study was the Stroke Risk Screening tool. Women with disabling conditions were less likely to have health insurance (85% versus 95% of women without disabling conditions). Women with disabling conditions also were less likely to see their healthcare providers during the previous year (85% versus 96%). One stroke risk factor differed significantly (p < .05) for subjects who had disabling conditions: history of transient ischemic attack (TIA). Just 2.6% of those without disabling conditions had a TIA history, versus 9.5% of those with disabling conditions. Rehabilitation nurses need to focus on early assessment for stroke risk factors and appropriate interventions, particularly for women who have a history of TIAs.

The United States Healthy People 2010 goal regarding stroke is “to improve cardiovascular health and quality of life through the prevention, detection, and treatment of risk factors; early identification and treatment of heart attacks and strokes; and prevention of recurrent cardiovascular events” in the U.S. population (U.S. Department of Health and Human Services, 2000). One objective is to increase awareness of the early symptoms and signs of stroke (U.S. Department of Health and Human Services).

Women 65 years of age and older have more chronic health conditions and disabling conditions than men in the same age group (Yee & Capitman, 1996). It is not currently known whether there are differences in risk factors for stroke in the disabled population. Stroke has been identified as a disabling condition that manifests differently in men and women (Haseltine & Jacobson, 1997). Of the 150,000 people who die of stroke each year, 90,000 are women (Haseltine & Jacobson). It also has been noted that women comprise 76% of nursing home admissions after a stroke (Allen & Phillips, 1997). Efforts to reduce the disproportional death and nursing home admission rates for women must emphasize stroke prevention. Women who increase their levels of physical activity have lower rates of stroke (Allen & Phillips).

This article presents a review of the literature, methodology, findings, and implications of a study comparing stroke risk factors among 204 women with and without disabling conditions. Before developing targeted health promotion efforts to reduce stroke risk for women, rehabilitation nurses need to know if disabled women face unique risk factors.

Background and Significance

Although nonmodifiable risk factors for stroke have been clearly identified and are important, primary and secondary prevention efforts focus on the assessment of modifiable risk factors (Goldstein et al., 2006; Sacco et al., 2006). The most prevalent risk factors are hypertension (HTN), history of transient ischemic attack (TIA), atrial fibrillation (AF), and diabetes. The incidence of HTN, cardiac conditions, and diabetes all is elevated in the disabled population in general (Fried, Bandeen-Roche, Kasper, & Guralnik, 1999). But it is not known whether these modifiable risk factors for stroke differ in women with and without disabling conditions.

HTN

HTN is the most important, prevalent, and treatable risk factor for stroke (Norris & Hachinski, 2001). The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (BP) provided guidelines for HTN prevention and management (Chobanian et al., 2003). No changes were made to the previous definition of HTN as a systolic BP of >140 mmHg or a diastolic BP of >90 mmHg (Joint National Committee on Prevention, 1997). The Seventh Report of the Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure created a new category for people with a systolic BP of 120–139 mmHg or a diastolic BP of 80–89 mmHg who should be considered prehypertensive and in need of life-study modifications to control risk (Chobanian et al.).

Patients with an uncomplicated HTN diagnosis should receive treatment comprising a thiazide-type diuretic, either alone or in combination with drugs from other classes (Chobanian et al., 2003). Research suggests that lowering the diastolic BP by 5–6 mmHg decreases the incidence of stroke by 42% and the rate of fatal stroke by 45% (Wright, 1998). The results of a metaanalysis suggest diuretics and beta blockers are the only agents shown to decrease the incidence of stroke in patients with HTN (Joint National Committee on Prevention, 1997). Most patients with HTN require two or more medications to decrease BP to <140/90 mmHg (Chobanian et al.).

Detecting HTN is a challenge because it is asymptomatic (Norris & Hachinski, 2001). The exact rate of HTN among people with disabilities is not known, but it is believed to be higher in this population compared to the nondisabled population (Fried et al., 1999). In one large study of stroke incidence, the age-adjusted relative risk of stroke in hypertensive subjects was 3.1 for men and 2.9 for women (Feinberg, Blackshear, Laupacis, Kronmal, & Hart, 1995).

It is well known that treating HTN is important after an initial stroke or TIA (Sacco et al., 2006). Yet one study of 644 women who had sustained a stroke or TIA found BP values that were higher than the national guideline of <140/90 mmHg 1 month after the stroke event. In fact, only 27% of the women who had a stroke or TIA had BP values within the recommended guidelines (Kernan et al., 2000).

The Working Group on Women’s Health of the Society of General Internal Medicine contends that the differences between men and women who have HTN justify the development of separate algorithms to guide appropriate treatment (Anastos et al., 1991).

TIA

A TIA is a focal neurological deficit that resolves completely within 24 hours (Norris & Hachinski, 2001). Between 200,000 and 500,000 individuals in the United States suffer a TIA each year, and approximately one-third of them will develop a stroke if untreated. A significant number of TIAs go unreported due to the transient nature of the symptoms (Hinkle, 2005). Consequently, a self-report mechanism for collecting information on TIA incidence may be more reliable than the rates reported in the medical literature.

A TIA leaves no permanent neurological deficit, but it affords healthcare professionals the opportunity to identify high-risk patients and initiate programs to prevent future permanent deficits (Norris & Hachinski, 2001). The initial approach to preventing recurrent TIAs is to identify and modify risk factors amenable to treatment. Important nursing interventions include ensuring risk factors such as HTN, smoking, heavy alcohol intake, AF, hyperlipidemia, diabetes, cardiac disease, coronary heart disease, left ventricular hypertrophy, and heart failure are addressed (Hinkle, 2005; Norris & Hachinski).

The first-line treatment for TIA is antiplatelet medication, the least costly being aspirin (ASA). A clinical trial studying the use of ASA to reduce stroke risk showed a risk reduction of 48% in men, with no significant effect for women (Dyken et al., 1977). A surgical procedure, carotid endarterectomy, is an effective treatment for TIAs caused by a 70%-or-greater occlusion of the carotid artery (Wolf et al., 1999). The recommendation for this procedure is based on the North American Symptomatic Carotid Endarterectomy Trial, in which just 30% of participants were women (Barnett et al., 1998). A study using 1992 Medicare data revealed that women undergo fewer carotid endarterectomies than men (Ramani et al., 2000). Women who have TIAs clearly are at a disadvantage because of ineffective therapy and low rates of surgical intervention.

AF

AF, a cardiac arrhythmia, occurs in 5.9% of people older than 65 years of age (Feinberg et al., 1995). It is estimated that AF causes 75,000 ischemic strokes each year (Wright, 1998), specifically embolic strokes (Norris & Hachinski, 2001).

For patients with AF, treatment prevents TIA and ischemic stroke. Dose-adjusted warfarin sodium (Coumadin) is administered to achieve an international normalized ratio target of 2.5 (Wolf et al., 1999). If warfarin is contraindicated, patients should be treated with aspirin (50–325 mg/d; Wolf et al.).

The absolute prevalence of AF in men and women is equal; however, because there are almost twice as many women than men who are older than age 75 in the United States, the absolute number of women with AF is higher than the number of men in this age group. For example, 55% of people with AF are women older than age 65, increasing to 63% after women reach the age of 75 years (Feinberg et al., 1995). Although cardiac conditions are known to be more common in the disabled population, the number of women with disabilities who have AF is unknown. It is also not known whether there are differences in AF in women with and without disabling conditions.

Diabetes Mellitus

Diabetes is diagnosed based on a fasting blood glucose level >126 mg/dl. Diabetes mellitus is a major risk factor for stroke (Norris & Hachinski, 2001). It also is associated with increased mortality, worse functional outcome, more severe disability, and a higher recurrence rate after a stroke (Sacco et al., 2006).

There are separate guidelines for BP management in secondary stroke prevention for people who have diabetes. After a stroke or TIA, BP should be maintained at <130/85 mmHg for people with diabetes. One study of 644 women found that 39% of those with diabetes who had a stroke or TIA had BP values within the guidelines 1 month after the event (Kernan et al., 2000).

Rates of glucose intolerance and diabetes are higher for women than for men (Haseltine & Jacobson, 1997). Rates of diabetes are higher in people with disabling conditions (Fried et al., 1999). These combined factors may put women with disabilities at higher risk for stroke compared to men. Further investigation of this important risk factor is warranted.

Additional modifiable stroke risk factors include carotid artery disease, history of heart disease, prior stroke (Wright, 1998), smoking (Allen & Phillips, 1997), family history of heart attack or stroke, excessive alcohol use, high cholesterol (Allen & Phillips), sickle cell disease (Gillum, Gorelick, & Cooper, 1999), and the use of illicit drugs (Blank-Reid, 1996). The heart-brain connection is well-established (Summers, Pyle, Stahl, & Hileman, 2000). People with cardiac impairment of any type, whether symptomatic or not, have more than twice the risk of stroke compared to those with normal cardiac function. Cigarette smoking and alcohol consumption increase blood viscosity, increasing stroke risk. Using illicit drugs causes stroke either by the direct effect of the drug or by complications from the method of administration (Norris & Hachinski, 2001).

The roles of gender and disability remain poorly understood as they relate to the modifiable risk factors for stroke. There are recognized differences between men and women for each risk factor (Hinkle, Smith, & Revere, 2006); however, it is not now known whether these differences exist between women with and without disabling conditions. The study reported in this article attempted to begin filling this knowledge gap. This study sought to determine whether women with and without disabling conditions differed in self-reported rates of HTN, TIA, AF, diabetes, or other risk factors, and their mean systolic BP, diastolic BP, or pulse rate on the day of screening.

Methods

Overview and Design

This study was a descriptive, nonexperimental two-group comparison. Data were gathered on the demographic characteristics and the nature of the disability in the sample. Women with and without a disabling condition were compared on self-reported rates of modifiable stroke risk factors. Women with and without a disabling condition also were compared on the mean systolic BP, diastolic BP, and pulse rate on the day of the screening.

Study participants were recruited when the investigators attended and set up tables at various health promotion, awareness, or educational days targeted toward health care for women and people with various disabilities. Participants filled out the Stroke Risk Screening tool and a short consent form to determine whether an individual had a disability and to describe the nature of the disability. Investigators measured BP and pulse (a quick test for AF) and then discussed each subject’s individual risk factors for stroke. Each participant was educated on the warning signs of stroke and given a copy of an American Stroke Association pamphlet as a guide to recognizing the signs of stroke (American Stroke Association, 2000). This pamphlet, available in English and Spanish, also reminds people that stroke is an emergency.

Sample Recruitment

A convenience sampling method was used to recruit women with and without disabling conditions to participate in individual stroke risk assessments. The goal was to recruit 64 women with disabling conditions and 64 women without disabling conditions for a sample of at least 128 participants. These numbers were determined by using a power analysis for ANOVA, a medium effect size (f = .25), power of .80, and an alpha of .05 (Cohen, 1988).

Study participation was open to those who presented for a stroke risk assessment. Informed consent was obtained from each participant, and the study was approved by the investigational review board at the primary investigator’s institution.

Measures

The Stroke Risk Screening tool was modified slightly for people with disabilities; the type size was increased to 14 point. A cover sheet featured an explanation of the study and solicited participant permission and data about the presence and nature of any disabling conditions.

The Stroke Risk Screening tool includes information about demographics and 15 questions about various stroke risk factors (Barker & Lamonte, 1999). The tool was introduced in 1999, and reliability and validity have yet to be reported. The authors documented each risk factor included on the tool with relevant literature (Barker & Lamonte).

Analysis

The Statistical Package for the Social Sciences (SPSS) Version 14 was used to analyze the data (SPSS, 2005). Sample demographics and characteristics were examined with descriptive statistics. ANOVA was used to compare the mean diastolic and systolic BPs of the two groups. Chi-square was used to test for differences in the self-reported rates of HTN, TIA, AF, diabetes, and other risk factors (Munro, 2005).

Results

Nearly 300 people had stroke risk screenings; 204 were women and they were included in this study. The demographic characteristics of women with and without disabling conditions are listed in Table 1. Approximately 95% of the women reported having a healthcare provider (92% of those with disabling conditions and 96% of those without). Fewer women with disabling conditions (86%) had seen their healthcare provider in the previous year, compared to those without disabling conditions (95%), a significant difference (c2 = 5.502; df = 1; p < .01). Fewer women with disabling conditions had health insurance (85%), compared to those without disabling conditions (95%), also a significant difference (c2 = 6.757; df = 1; p < .001). The women with disabling conditions tended to be older (m = 58), compared to those without (m = 54), another significant difference (t = 1.923, p = .05).

The nature of the conditions identified by the women can be found in Table 2. Neurological conditions included Parkinson’s disease (n = 2), cerebral palsy (n = 5), spina bifida (n = 3), prior stroke (n = 6), paralysis (n = 2), and Alzheimer’s disease (n = 2). Other conditions included a wide variety of physical and mental conditions reported as blindness, amputation, fibromyalgia, back injury, osteoporosis, learning disabilities, cancer, HTN, and mental disabilities.

Self-report data on the major modifiable risk factors for stroke are reported in Table 3. Approximately 9.5% of women with disabling conditions self-reported a history of TIAs, compared to 2.6% of those without, representing a significant difference (c2 = 3.651; df = 1; p = .05). More women without disabling conditions (2.6%) reported higher rates of combined smoking and birth control pill use compared to those with disabling conditions (0%; c2 = 3.263; df = 1; p < .07).

The systolic BP measured on the day of screening was not significantly different for women with disabling conditions (m = 132 mmHg, + 19) compared to those without disabling conditions (m = 129 mmHg, + 18). There was no significant difference in the diastolic BP for the women with disabling conditions (m = 77 mmHg, + 12) compared to those without disabling conditions (m = 77 mmHg, + 10). The mean pulse rate for women with disabling conditions was 77 (+13) compared to 73 (+10) for those without, which is a significant difference (t = 2.459, p = .015). There was no significant difference in the total number of self-reported risk factors between the two groups.

Discussion

The primary purpose of this study was to determine whether women with and without disabling conditions differed in self-reported rates of HTN, TIA, AF, diabetes, or other risk factors. Women with a disabling condition reported higher rates of a history of a TIA compared to those without a disabling condition. Community-based stroke prevention programs already attract more women than men (Lindsey, 2000); however, concerted and creative efforts need to be made to reach out to women with disabling conditions and a history of TIAs to help decrease their stroke risk.

HTN, identified as the most common preventable stroke risk factor in the general population (Benson & Sacco, 2000; Lindsey, 2000), also is prevalent in both groups of women in this study. In the United States, HTN is present in an estimated 38% of people between the ages of 50 to 59 (Norris & Hachinski, 2001). The lifetime risk of developing HTN for middle-age and elderly men and women is estimated at 90%, presenting an enormous public health burden (Ramachandran et al., 2002). Women in the study with a disabling condition had a self-reported HTN rate of 38% and those without reported 42% (Table 3), thus all the women are at high risk. Every patient with HTN requires treatment (Norris & Hachinski). A 7-point decrease in diastolic BP over time is associated with a 46% reduction in risk of stroke. All women should be targeted for health promotion efforts to identify HTN and have it treated to reduce stroke risk.

Smoking is another known risk factor for stroke, and all patients who smoke should be counseled to quit despite the fact this study showed a trend toward more women without disabling conditions reporting higher rates of combined smoking and birth control pill use compared to those with disabling conditions. Rehabilitation nurses are ideally placed for intervention; a recent metaanalysis suggests nursing intervention is effective for patients when it is initiated during an episode of acute care (Rice, 2006).

The largest group of participants identified their disabling condition as hearing impairment (Table 2); this reflects the fact that investigators set up a table at a 3-day National Hard of Hearing Conference. In the 1997 National Health Interview Survey, 12.4% of adults 18 years or older identified their disability as a vision and/or hearing limitation (National Center for Health Statistics, 2000). Two participants in the current study identified their disability as “mental,” while 6.3% of the National Health Interview Survey participants reported depression or emotional limitation (National Center for Health Statistics). Of note, 11% (n = 14) of participants in this study said they had more than one disabling condition, indicating perhaps a fairly high level of disability in this group.

The results of this study suggest women with disabling conditions are at a disadvantage in several respects. Those with disabling conditions were highly educated, yet older, and less likely to have health insurance and see a healthcare provider during the previous year, compared to women without disabling conditions. Rehabilitation nurses, who routinely interact with disabled women, can make appropriate referrals to social work for assistance in procuring health insurance for this disadvantaged group. Referral to a local nurse-managed health center is another alternative.

Limitations

This study had several limitations. One was the use of a convenience sample; future studies should direct efforts at obtaining a larger and more representative sample of adults with disabilities. Future studies also need to assess the reliability of the Stroke Risk Screening tool, which primarily relies on self-report.

Conclusion

The most effective way to reduce the burden of stroke is through prevention. This study provides findings on the specific stroke risk factors for women with and without disabling conditions. Further work is needed to increase the number of people who are appropriately counseled about stroke risk factors.

Acknowledgments

This project was conducted while Janice L. Hinkle was an assistant professor at Villanova University and it was funded by the Research Seed Fund of the Health Promotion for Women with Disabilities Project of Villanova University College of Nursing, funded by Bristol-Myers Squibb Foundation.

Rosalind Smith’s involvement in this project was sponsored by Project IMPART (Improving Minority Professionals’ Access to Research Tracks), funded by the National Institute of General Medical Science, National Institutes of Health.

About the Authors

Janice L. Hinkle, PhD RN CNRN, is a senior research fellow at Oxford Brookes University in Littlemore, Oxford. Address correspondence to her at Janice.Hinkle@ndm.ox.ac.uk.

Rosalind Smith, RN, is a nurse working in Philadelphia, PA.

Karen Revere is a medical student at the University of Pennsylvania in Philadelphia, PA.

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