The Weight of the Evidence: Hypertension in Women
Abstract & Commentary
By Susan T. Marcolina, MD, FACP. Dr. Marcolina is a physician at the HealthPoint Community Health Clinic in Kent, WA; she reports no financial relationship to this field of study.
Synopsis: Lifestyle and dietary modifications are important tools for both prevention and adjunctive treatment of hypertension, an important risk factor for cardiovascular disease, the leading cause of death for women. The strongest risk factor for developing new-onset hypertension in this prospective 14-year cohort study was a BMI > 25 kg/m2, a designation encompassing both overweight and obese individuals. After controlling for multiple variables in a population of healthy, young female professionals, overweight women (BMI, 25-29.9 kg/m2) had an almost three-fold risk of developing hypertension, whereas obese women (BMI ≥ 30 kg/m2) had almost a five-fold increased risk. This adds to the compelling evidence that weight loss is a prudent strategy for young overweight women to decrease their risk of incident hypertension.
Source: Forman JP, et al. Diet and lifestyle risk factors associated with incident hypertension in women. JAMA 2009;302:401-411.
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The joint national committee on hypertension, 7th report (JNC-7), established a threshold of systolic blood pressure of 120-139 mm Hg or diastolic blood pressure of 80-89 mm Hg as prehypertension and advised health-promoting lifestyle modifications for all patients to prevent cardiovascular disease.1 Forman et al, in this longitudinal cohort study of more than 83,000 healthy, young professional women from the second Nurses' Health Study, convincingly quantified the relative importance of six low-risk lifestyle and dietary factors (see Table, above) to incident hypertension using the population attributable risk (PAR) statistic,2 which estimates the percentage of all cases of disease attributable to specific risk factors for a given population. These researchers dichotomized each lifestyle factor into risk vs. no risk for this analysis and adjusted for age, race, family hypertension history, use of oral contraceptives, and smoking status. Over the 14 years of this study, the strongest risk factor for hypertension was an increased BMI. In fact, the authors calculated the PAR for new-onset hypertension to be 40% for subjects with a BMI ≥ 25 kg/m2. They found that the other five modifiable risk factors were also associated with long-term development of hypertension, but to a lesser degree than increased BMI. Specifically, non-narcotic analgesic use greater than once weekly, not following a DASH-style diet, not exercising vigorously daily, consumption of more than 10 g/d of alcohol, and folate supplementation less than 400 mg daily were associated with PARs of 17%, 14%, 14%, 10%, and 4%, respectively. Upon further analysis, they found that women with specific combinations of 3, 4, 5, and 6 low-risk factors progressively lowered their risk for developing hypertension. For women with a normal BMI, daily vigorous physical activity, and a DASH-style diet, 53% of new-onset hypertension might be prevented; if they had all six low-risk factors, 78% of new cases of hypertension might be prevented. Notably, only 0.3% of this young, professional study population had all six low-risk factors.
Commentary
The prevalence of hypertension in women is 30%; in certain subgroups, such as African-American women, the prevalence is up to 44%.3 Although the 2nd Nurses' Health Study population was primarily white, other studies involving more ethnically diverse cohorts, such as the Coronary Artery Risk Development in Young Adults (CARDIA) study, also showed that the lifestyle and dietary practices mentioned above were important risk contributors to the development of hypertension and coronary artery disease.4
The National High Blood Pressure Education Program, established in 1972, has been instrumental in increasing public and professional awareness of the importance of blood pressure control through resources available on the web and in printed form in multiple languages.5 The following National Heart Lung and Blood Institute web site also has specific resources targeted for women: www.nhlbi.nih.gov/hbp/issues/issues.htm.
Hypertension is a known risk factor for cardiovascular disease as well as stroke, congestive heart failure, and renal disease, and the prevalence increases with age.6 Given that 66% of non-institutionalized U.S. adults older than age 20 and 17% of children ages 6-19 years are overweight or obese and at risk for the development of hypertension,7,8 interventions to assist patients with weight loss have enormous potential to improve quality of life on an individual level and to reduce disease burden and medical costs in the aggregate.
Primary care physicians play a central role in the early identification of patients at risk for hypertension due to an elevated BMI. It is important, therefore, to evaluate patients for cardiometabolic risk by calculation of BMI with height and weight measurements, as well as a measurement of the waist circumference, the clinical determinant of abdominal adiposity.
Waist circumference should be measured on the skin with a tape in the horizontal plane at the level of the iliac crest. The measurement should be made at the end of a normal expiration and the tape should be tight without compressing the skin. Women with a waist circumference greater than 35 inches (31.5 inches for women of Chinese, Japanese, South Asian, or South or Central American descent) should be considered as one risk category above that defined by their BMI and are at higher risk of diabetes, dyslipidemia, hypertension, and cardiovascular disease.9
As physicians evaluate overweight and obese women, there are elements from the history that can help in the management such as:
1. Family history
2. Age of onset of weight gain
3. Minimum/maximum adult weight
4. Events associated with weight gain
5. Most recent weight-loss attempts
6. Previous weight-loss modalities used and complications thereof.
It is important to note that cigarette smoking complicates treatment because smoking cessation is often accompanied by weight gain.
A complete review of systems can uncover comorbidities such as obstructive sleep apnea, endocrine disorders such as polycystic ovarian syndrome, Cushing's disease, diabetes, depression, eating disorders, chronic pain syndromes, or substance abuse, which may require additional evaluation with diagnostic testing and referral to different specialists for treatment.9 Many types of medications can cause weight gain or prevent weight loss such as antipsychotics, anticonvulsives, antidepressants, oral contraceptives, antihypertensives (particularly alpha and beta blockers),10 corticosteroids, antihistamines, or diabetes treatments such as insulin, thiazolidinediones, or sulfonylureas.10,11 Often there is an alternative medication that can be used that is weight-neutral. The overweight/obese patient can be more successful with weight loss if comanaged by the primary physician with a team of professionals that includes a dietitian, psychologist/support group, and a fitness trainer, depending upon the patient's needs.
The National Weight Control Registry has identified four specific behaviors key to successful long-term weight management12:
1. Self-monitoring: Record/monitor daily food diaries and limit certain foods or food portions, monitor weight > once weekly.
2. Low-calorie, low-fat diet: Total energy intake: 1,300-1,400 kcal/d with 20%-25% fat.
3. Daily breakfast intake.
4. Regular physical activity: 2,500-3,000 kcal/week.
A useful National Institutes of Health (NIH) Publication (No. 08-4992) from the Weight-control Information Network (WIN) entitled "Healthy Eating & Physical Activity Across Your Lifespan" provides information to patients about menu planning, portion control, exercise ideas, and implementation tools, as well as additional resources. It can be downloaded from the NIH web site at www.win.niddk.nih.gov.
Clinical guidelines from the American Heart Association and the National High Blood Pressure Education Program recommend limiting alcohol intake to two drinks (10-20 g alcohol) or less daily in men and only one drink or less (10 g) in women for the primary prevention of hypertension.13 Among the studies that form a basis for these recommendations is a meta-analysis by Xin et al of randomized clinical trials that included patients who initially consumed 3-6 daily alcoholic beverages. They found that with an average of 67% reduction in alcohol consumption, the net change in systolic blood pressure was -3.3 mm Hg and -2.0 mm Hg in diastolic blood pressure.14
Sesso et al, in a cohort of patients from the Women's Health Study and the Physicians' Health Study, found that the risk for developing hypertension for both sexes substantially increased if patients consumed more than two alcoholic beverages daily.15 Interestingly, among hypertensive patients with greater daily consumption of alcoholic beverages (more than two daily), blood pressure reductions occurred relatively rapidly (i.e., within weeks) after reductions in alcohol intake.14 The blood pressure-lowering effects of alcohol reduction are similar to the blood pressure-lowering effects of dietary sodium reduction.16,17
Cook et al, in an overview of data from observational studies and randomized trails, suggested that the 2 mm Hg diastolic blood pressure reduction seen in studies of dietary sodium restriction and alcohol intake could be expected to result in a 17% decrease in the incidence of hypertension, a 6% decrease in coronary artery disease and a 15% reduction in the risk of strokes and transient ischemic attacks.18
This longitudinal cohort study demonstrated the importance of encouraging patients to adopt as many of the six low-risk lifestyle and dietary habits as possible, the most important of which is maintenance of a normal weight. Within the realm of realistic possibility in daily practice, it is important not to let perfect be the enemy of good. If patients are adopting some of the low-risk lifestyle measures, even if not optimally, they should be applauded and encouraged in their efforts to improve their overall health and decrease their risk for developing hypertension. Continuous reinforcement and monitoring of individual patient progress in adoption of low-risk lifestyle and dietary factors can help to reduce the risk of hypertension for women during their lifetime.
References
1. Chobanian AV, et al; Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. National Heart, Lung, and Blood Institute; National High Blood Pressure Education Program Coordinating Committee. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 2003;42:1206-1252.
2. Forman JP, et al. Diet and lifestyle risk factors associated with incident hypertension in women. JAMA 2009;302:401-411.
3. National Center for Health Statistics. Health, United States, 2008, with Special Feature on the Health of Young Adults. Hyattsville, MD: 2009. Available at: www.cdc.gov/nchs/data/hus/hus08.pdf.
4. Liu K, et al. Blood pressure in young blacks and whites: Relevance of obesity and lifestyle factors in determining differences. The CARDIA study. Coronary Artery Risk Development in Young Adults. Circulation 1996;93:60-66.
5. U.S. Department of Health and Human Services. National Heart Lung and Blood Institute: National Institutes of Health. National High Blood Pressure Education Program. Available at: www.nhlbi.nih.gov/about/nhbpep/index.htm. Accessed Aug. 3, 2009.
6. Fields LE, et al. The burden of adult hypertension in the United States, 1999 to 2000: A rising tide. Hypertension 2004;44:398-404.
7. Centers for Disease Control and Prevention. Overweight and Obesity. Data and Statistics. Available at: www.cdc.gov/obesity/data/index.html. Accessed Aug. 2, 2009.
8. Centers for Disease Control and Prevention Fast Stats on the Prevalence of Obesity: Table 76: Overweight among children and adolescents 6-19 years of age, by selected characteristics: United States 1963-1965 through 2003-2006. Available at: www.cdc.gov/nchs/data/hus/hus08.pdf. Accessed Aug. 2, 2009.
9. The Practical Guide: Identification, Evaluation and Treatment of Overweight and Obesity in Adults. October 2000. NIH Publication Number 00-4084.
10. Cheskin LJ, et al. Prescription medications: A modifiable contributor to obesity. South Med J 1999;92: 898-904.
11. Lebovitz HE. Differentiating members of the thiazolidinedione class: A focus on safety. Diabetes Metab Res Rev 2002;18(Suppl 2):S23-S29.
12. Klem ML, Wing RR. A descriptive study of individuals successful at long-term maintenance of substantial weight loss. Am J Clin Nutr 1997;66:239-246.
13. Whelton PK, et al. Primary prevention of hypertension: Clinical and public health advisory form the National High Blood Pressure Education Program. JAMA 2002;288:1882-1888.
14. Xin X, et al. Effects of alcohol reduction on blood pressure: A meta-analysis of randomized controlled trials. Hypertension 2001;38:1112-1117.
15. Sesso HD, et al. Alcohol consumption and the risk of hypertension in women and men. Hypertension 2008; 51:1080-1087.
16. He J, et al. Role of sodium reduction in the treatment and prevention of hypertension. Curr Opin Cardiol 1997;12:202-207.
17. Puddey IB, et al. Alcohol is bad for blood pressure. Clin Exp Pharmacol Physiol 2006;33:847-52
18. Cook NR, et al. Implications of small reductions in diastolic blood pressure for primary prevention. Arch Intern Med 1995;155:701-709.
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