|Home | About | Journals | Submit | Contact Us | Français|
Purpose: This study examined whether rural women, who had a high prevalence of prehypertension and hypertension upon enrollment in a wellness program, would also have a high prevalence of other cardiovascular disease risk factors such as low fitness and/or dyslipidemia. Methods: Data were analyzed from 225 rural women, ages 50-69, enrolled in a healthy eating and activity clinical trial. Cardiovascular health histories, fitness measures, blood pressure, and fasting blood serum samples were collected following standardized protocols at rural research offices. Chi-square and MANOVA were performed to examine differences in health characteristics, lipids, and fitness across blood pressure categories. Results: Fitness indicators of estimated VO2max, 1-mile walk time, and resting heart rate differed between the blood pressure groups, with those in the prehypertensive and hypertensive groups having less desirable profiles than those in the normotensive group. Triglyceride levels of 150 mg/dL or greater, were observed in 36%, 32%, and 16.7% of women who had hypertensive, prehypertensive, and normal blood pressures, respectively. Conclusions: The need for routine blood pressure screenings by practitioners is reinforced by finding that rural women screened via PAR-Q and/or physician clearance had a high prevalence of prehypertensive and hypertensive blood pressures, in addition to low fitness and nonoptimal triglycerides. Practitioners need to provide counselling based on results and refer to other providers as appropriate.
Cardiovascular disease is identified as the leading cause of death among women in the USA.1 Rural women are especially vulnerable, having a higher incidence of heart disease and diabetes and receiving fewer preventive health screenings than their urban counterparts.2,3 Rural populations in the USA differ from each other, making it challenging for providers to assess the health risks unique to a regional area and reinforcing the need for a vigorous research agenda about health needs for rural women.4
Because women's lifetime risk of cardiovascular disease is high, prevention is advocated for all women.5 Assessment of cardiovascular disease risk factors, such as blood pressure, lipids, obesity and fitness, in midlife and older rural women is needed so that practitioners and the women they treat may be proactive in preventive screening and interventions to modify risk. Physical therapists and other health care providers should routinely assess pulse and blood pressure as part of their regular and wellness practices.
The risk of hypertension in women increases with age and becomes more prevalent among women after age 59 than among men, possibly due to changes associated with menopause.1 The classification of prehypertension, defined by the Joint National Committee on the Prevention, Detection and Treatment of High Blood Pressure (JNC 7) as a systolic blood pressure of 120-139 mmHg and/or diastolic blood pressure of 80-89 mmHg, was created to identify individuals considered at risk for developing hypertension (systolic pressure ≥140 mmHg and/or diastolic pressure ≥ 90 mmHg).6,7 A recent estimate of the prevalence of prehypertension and hypertension among white women in the USA was 38.5% and 34.9%.8 The literature suggests that women are likely to be unaware of the threat to health that prehypertension or hypertension may pose.9 Women who are informed of cardiovascular risk, including prehypertension or hypertension, were found to be more likely to take preventive action.10
Hypertension and prehypertension have been shown to be associated with other cardiovascular risk factors in women, including obesity and hypercholesterolemia.8,11 A meta-analysis showed that a combination of high systolic blood pressure and high cholesterol was more than additive, although less than multiplicative, in terms of relative risk for cardiovascular disease, as the hazards of higher systolic blood pressure at all levels of cholesterol, and the hazards of higher cholesterol at all levels of systolic blood pressure have been clearly documented.12
The American Heart Association's 2007 guidelines for cardiovascular disease prevention in women highlight the need to increase physical activity to reduce disease risk.1 Kodama and associates13 comment it is rare for clinicians to consider cardiorespiratory fitness as a marker of cardiovascular disease risk because the relationship between the two has not been well established. Their meta-analysis included 33 eligible studies with findings that better cardiorespiratory fitness was associated with lower risk of all-cause mortality and cardiovascular disease.13
Few studies have focused on cardiovascular risk factors unique to rural women, and of those, studies have focused on self-reported physical activity as opposed to cardiorespiratory fitness.2,3 Roddy et al2 examined the cardiovascular risk of rural Midwestern women age 40 years and older, finding that dyslipidemia in women was commonly unrecognized and untreated, and that women received suboptimal preventive care for cardiovascular disease; however, they did not include any physical activity or fitness data.2 Feresu et al3 reported that rural residence was related to cardiovascular risk factors, such as obesity and high blood pressure, especially among low income women ages 40 or older.3 They reported that high blood pressure risk was greatest among women ages 50-64 years, with women aged 60-64 having the greatest risk for high total cholesterol.3
We were surprised to find the majority of women who enrolled in our Wellness for Women community-based trial for promoting healthy eating and activity had blood pressure readings that were in the prehypertensive (55.2%) or hypertensive (20.8%) ranges.14,15 As fewer than 25% of these rural women had a baseline normotensive blood pressure reading, this secondary analysis was designed to conduct a more detailed examination than had previously been reported of the cardiovascular health histories, medication usage, fitness indicators, and lipid profiles of rural women, ages 50-69, who were enrolled in our wellness program. We specifically examined whether the cardiovascular health histories, medication usage, fitness, and lipids differed between groups of rural women who were found to have blood pressure readings that were normotensive, prehypertensive or hypertensive.
The Wellness for Women project was a community-based clinical trial designed and conducted by an interdisciplinary team of nurses, a physical therapist, and a dietician with a goal to promote healthy eating and physical activity among rural Midwestern women. The study design and details of the methodology, including the participant flowchart, have been reported elsewhere.14,16 Briefly, the Wellness for Women project used a repeated-measures experimental comparison group design to compare a tailored behavior-change intervention with a generic behavior-change intervention to increase healthy eating and activity among women 50-69 years. Over 12 months, women received by mail either 18 generic newsletters or 18 computer-tailored newsletters, with tailoring for each woman based on her self-reported eating and physical activity behaviors as well as her perceptions about benefits, barriers, self-efficacy, and interpersonal support for eating and physical activity.
A telephone random-digit dialing method was used to recruit 225 women from two geographically separate but demographically similar rural areas, classified as nonmetropolitan, meaning large rural areas or completely rural.17 The land telephone ownership rate was 97% at the time. Randomization of two geographical areas to intervention (computer-tailored newsletters) or comparison (generic newsletters) groups was needed to reduce the between-group contamination risk due to the high probability for rural women in a given area to interact and potentially share information. Women provided informed consent following the University of Nebraska's Institutional Review Board procedures.
Inclusion criteria included: able to walk one-mile distance continuously without an assistive device, able to answer “no” to all questions on the Physical Activity Readiness Questionnaire18 or to obtain physician clearance, and not involved in ongoing cardiac or physical rehabilitation. Women were excluded if they had any restrictions that would preclude them from following the Healthy People 2010 recommendations for both healthy eating and physical activity. Women were 57.9 ± 5.6 years, non-Hispanic white (99.1%), married (70.2%), employed outside of the home part- or full-time (64.9%), had some education beyond high school (75.1%), and lived in a household with $40,000 or more income (53.8%).
Women completed self-reported demographic and health history questionnaires while individually supervised by a research nurse at one of two rural sites. The nurses received intensive training about all measurement procedures and underwent periodic observation and assessment of their compliance with data collection procedures by investigators on-site.
A standard clinical scale was used to measure body weight and height. Body mass index (BMI) was calculated as weight in kilograms divided by height in meters-squared and women were classified as normal weight (BMI < 25 kg/m2), overweight (BMI = 25-29.9 kg/m2) or obese (BMI ≥ 30 kg/m2).19
Resting heart rate and blood pressure were measured following 5 minutes of quiet sitting. A calibrated mercury sphygmomameter was used for blood pressure measures following standard auscultatory protocol.20 Participants were told to avoid caffeine, intensive exercise, and smoking at least 30 minutes prior to blood pressure measurement. Nurses recorded measures to the nearest 2 mmHg using the first and fifth Korotkoff sounds. Two or more readings separated by 30 seconds of rest were averaged; however, if the first two readings differed by more than 5 mmHg, additional readings were obtained until two readings differed by less than 5 mmHg. Readings were classified as normotensive, prehypertensive, or hypertensive per JNC 7 guidelines described earlier.6,7
Blood was drawn into a 5mL vacutainer tube from an antecubital vein after a minimum of 12 hours of fasting. After clotting for 30 minutes to 1 hour, the blood was centrifuged at 3500 RPM for 10 minutes. The serum was separated and transferred to an appropriately labelled transport tube. The sample was stored frozen at minus 20° Celsius in a nonself-defrosting freezer that was monitored daily for temperature. The frozen serum was shipped on dry ice to the University laboratory for analysis within two weeks of collection where the sample was analyzed for total cholesterol, trigylcerides, high-density lipoprotein (HDL) cholesterol, and low-density cholesterol (LDL). Based upon the American Heart Association guidelines for women, total cholesterol was defined as optimal (< 200 mg/dL), borderline risk (200 to < 240 mg/dL) or as hypercholesteremia (240 mg/dL or greater).1 Optimal HDL cholesterol was defined as greater than 50 mg/dL. The LDL cholesterol was defined as optimal (< 100 mg/dL), near optimal (100 < 130 mg/dL) or high (130 mg/dL). Triglycerides were classified as normal if they were < 150 mg/dL.1
The 1-mile walk test, validated and having high test-retest reliability among similar populations of older or sedentary women, was used to estimate cardiorespiratory fitness.21,22 This submaximal field test required the women to complete a 1 mile walk on an indoor track as fast as they were able. Measures of age, walk-time, and a 15-second post-exercise heart rate were used for calculating the estimation of VO2max using the female equation validated by Kline et al.21 Our preliminary work using this equation showed high test-retest reliability (ICC=.96) over a one-week period for women ages 50–69.22 All women were able to complete the 1-mile walk. We categorized the women as having low estimated cardiorespiratory fitness (< 24.5 ml/kg/min) or average or higher (≥ 24.5 ml/kg/min) based upon ACSM guidelines for women ages 50-69.23 Fifteen of the 159 women categorized as having low fitness had such slow walk-times that we were unable to capture an estimated VO2 max using the regression equation.
SPSS version 17.0 for Windows (SPSS Inc, Chicago, IL) was used to analyze the data. Descriptive statistics were used to describe the sample. Chi-square analysis was used to compare the proportion of women in each blood pressure category by self-reported cardiovascular disease, medication usage, and levels of fitness and lipids. A MANOVA (alpha of 0.05) with post-hoc Bonferroni correction adjustment for multiple comparisons (alpha of 0.017) was used to compare serum lipid levels and fitness measures across the blood pressure categories.
Overall, 30 women (13.3%) reported a medical history of a cardiovascular-related disease (myocardial infarction, stroke, congestive heart disease, or diabetes). These rural women had a high prevalence of lipid-related cardiovascular risk factors with over half of women (51.6%) having total cholesterol values greater than 200 mg/dL, 40% of women having LDL cholesterol of greater than 130 mg/dL, and 29.3% of women having triglycerides of 150 mg/dL or greater. When health histories, fitness and lipid characteristics were reported by blood pressure groups, we found the majority of the women with normotensive blood pressures had a high prevalence of other cardiovascular risk factors such as overweight or obesity (61%), high LDL cholesterol (38.9%), and low fitness (50%) (See Table Table1).1). Women with prehypertensive and hypertensive blood pressures had a higher prevalence of taking a lipid lowering medication, being overweight or obese, demonstrating slower walk-times and having lower cardiorespiratory fitness than women with normotensive readings. The MANOVA results were not significant for differences in blood lipid levels across blood pressure categories (see Table Table22).
In the prehypertensive and hypertensive groups, distributions of the 1-mile walk test and VO2 max were not normal and had larger variances than did the normotensive group. Deletion of 4 outliers (z-scores > 3.0) corrected both the nonnormality and heterogeneity of variances. Results from analyses with and without the outliers did not differ substantially and led to identical statistical conclusions, so only the analyses including all cases are reported in Table Table3.3. The MANOVA results demonstrated significant overall differences in fitness measures across the blood pressure categories. When the univariate results were examined, all three measures were significantly different across the blood pressure categories. Post hoc Bonferroni comparisons revealed that the normotensive group had better estimated VO2 max and lower resting heart rates than both the prehypertensive and hypertensive groups. Women in the prehypertensive group demonstrated better estimated fitness than women in the hypertensive group. Women in the normotensive group also had faster walk-times than women in the prehypertensive group.
This secondary analysis from our Wellness for Women project provided a detailed examination of health histories, self-reported medication usage, fitness and lipid profiles among midlife and older rural women as categorized by blood pressure readings that had not been previously reported. As practitioners increasingly become more involved in routine health screenings for clients entering rehabilitation or wellness activities, they need to assist clients in becoming aware of their cardiovascular risk, particularly within this understudied and hard-to-reach population of rural women.
Because the majority of women who enrolled in the Wellness for Women project had blood pressures that were in the prehypertensive or hypertensive ranges, we anticipated they might also have a high prevalence of cardiovascular disease, medication usage, dyslipidemia, and lower fitness. We found the hypertensive group had a higher prevalence of self-reported cardiovascular disease and non-optimal values of HDL cholesterol, trigyclerides, and estimated cardiovascular fitness when compared to the normotensive group. Importantly, the majority of women with normotensive readings had a high prevalence of other cardiovascular risk factors such as overweight or obesity, high LDL cholesterol, and low fitness.
When compared to results from a similar rural Midwestern population, these women had a higher prevalence of prehypertension (55.2% vs 33.1%) and hypertension (20.8% vs 10.3%).3 When compared to national data of non-Hispanic white women ages 20 or older, our women had a higher prevalence of total cholesterol above 200 mg/dL (51.6% vs 47.7%), but less than regional data of Midwestern women with lower socioeconomic status ages 40 or older (51.6% vs 54.6%).3,24 Our results for LDL cholesterol and triglycerides were also similar to regional data of Midwestern women ages 40 or older, however the prevalence of high triglycerides among our women (29.2%) was higher than those reported nationally and the mean scores of the total cholesterol, HDL, LDL, and triglycerides were similar to the national average reported for non-Hispanic white women ages 20 or older.3,5 Whether differences between our results and others could be attributed to differences in methodology or other differences such as rates of overweight and obesity remains unclear.
This study of midlife and older rural women was unique as we included an assessment of estimated cardiorespiratory fitness. Women with blood pressures that were prehypertensive or hypertensive had higher percentages of low estimated cardiovascular fitness. Kodama et al13 indicated that a minimal level of cardiorespiratory fitness may be important for overall health. When expressed in terms of walking speed, women age 50 should be able to walk at a rate of 3 miles per hour yet only 72.7% of our women were able to walk a mile at that minimum rate. The 15 women whose walk-times were too slow to permit an estimation of the VO2 max using the regression equation were obese. Ohtake's25 review of the literature indicated obesity was associated with slower gait speeds and other adverse effects such as increased joint forces and skin breakdown in the thigh regions. The metaanalysis completed by Kodama et al13 showed those individuals with low cardiorespiratory fitness had a 56% higher risk of heart disease events such as heart attack or stroke when compared to individuals with a high cardiorespiratory fitness. Compared to those with an intermediate level of fitness, those with a low cardiorespiratory fitness had a 47% higher risk of heart disease events.13 As physical therapists are well-trained to provide assessments of cardiorespiratory fitness, the findings of our study suggest therapists should become more actively engaged in health promotion screening and counselling for fitness.
Because this was a secondary analysis of our baseline data from the Wellness for Women project, a specific listing of medications used by the women was not available. A limitation of this study was that we therefore were unable to verify by physician or pharmacist professional opinion, which, if any, medications were appropriately classified for management of blood pressure, lipid levels, or other types of cardiovascular symptoms or diseases. We relied on the women's self-report of their medication use of lipid-lowering and hormone-replacement medications; data were not available about their medication use for blood pressure management. As the JNC 76,7 classification for hypertension includes those taking antihypertensive medications, it is possible that women with normotensive or prehypertensive blood pressure readings, would actually be considered hypertensive.
Acknowledging this limitation, we believe our findings are highly relevant to clinical practice, as women screened via PAR-Q and/or physician clearance had such a high prevalence of blood pressure readings above normal. All women who enrolled in our wellness program were informed of their blood pressure readings, with counselling provided and referrals made to their primary care providers as appropriate.
While we did not ask the women why they were using hormone-replacement therapy, we found nearly half (45.8%) reported taking hormone-replacement therapy, with no differences in usage observed between the groups of normotensive, prehypertensive, and hypertensive women. Wassertheil-Smoller et al26 found that women using hormone therapy had a 25% greater likelihood of hypertension when compared to women who never used hormone therapy or those who had used hormone therapy in the past. Current guidelines indicate that hormone therapy should not be used as a primary or secondary prevention method for reducing cardiovascular disease risk in women.27
Strengths of the study included successful recruitment of a large sample of a difficult-to-reach population of rural Midwestern women ages 50 to 69 through random-digit dialing, and including a screening for selected cardiovascular disease risk factors such as fitness and lipids that are not typically included as part of a wellness program prescreening assessment. We did not capture a comprehensive screening of cardiovascular disease risk factors, such as family history of cardiovascular disease, smoking, or fasting blood glucose, which would be useful to collect in future studies to permit risk stratification. These findings may or may not be generalized to rural women from other geographical areas.
While the inclusion and exclusion criteria for enrollment in the Wellness for Women project were strict, requiring most women to seek medical clearance before enrollment, the finding that 76% (n=171) of the women had blood pressure readings that were prehypertensive or hypertensive suggests that these women were either unaware of their blood pressure status and/or their blood pressure was not well-managed. These findings reinforce the need by all practitioners to assess vital signs as part of routine clinical and wellness practice.
The high prevalence of prehypertensive and hypertensive blood pressure readings among these midlife and older women at the time of enrollment in a community-based wellness program highlights the merits of routine assessment and screening of blood pressure and other vital signs by clinicians.
Prehypertensive and hypertensive blood pressures were associated with a high prevalence of overweight and obesity and lower estimated cardiorespiratory fitness, suggesting this population of rural women was especially vulnerable to cardiovascular events. Upon discovering prehypertensive or hypertensive blood pressure levels in clients, practitioners should consider providing additional counselling about the potential presence of other cardiovascular risk factors, including overweight and obesity, low cardiorespiratory fitness and non-optimal lipid profiles and refer to other providers as appropriate.
This research was supported by Grant R01 NR04861 from the National Institute of Nursing Research, National Institutes of Health, with supplemental funding for lipid testing from The Nebraska Medical Center and the University of Nebraska Medical Center. The authors thank Melody Hertzog, PhD, for reviewing the statistical analysis, Dawn Garcia, BSN, RN, and Cathy Vasko, BSN, RN, for their work as research nurses and Maureen Oberdorfer, MPA, BSMT, and Matthew Rutledge, MA, for their contributions to the project as Project Coordinator and Information Technologist, respectively.