Erectile Dysfunction in the US — Prevalence and Risk Factors
Abstract & Commentary
By Allan J. Wilke, MD, Residency Program Director, Associate Professor of Family Medicine, University of Alabama at Birmingham School of Medicine—Huntsville Regional Medical Campus, Huntsville. Dr. Wilke reports no financial relationship to this field of study.
Synopsis: Erectile dysfunction is common among US males and associated with poor lifestyle habits and the metabolic syndrome.
Source: Selvin E, et al. Prevalence and risk factors for erectile dysfunction in the US. Am J Med. 2007;120:151-157.
Using data from the 2001-2002 National Health and Nutrition Examination Survey (NHANES), Selvin and colleagues analyzed the responses of men over 20 years of age about their experiences with erectile dysfunction (ED). This national, cross-sectional sub-sample of 2126 non-institutionalized men was further divided into men over 40 years to examine the role of cardiovascular risk factors. Men with a history of prostate cancer were excluded from this analysis, because of the known adverse effects on male sexual function that cancer treatment can cause. ED was defined as "sometimes able" or "never able" to attain and maintain an erection. NHANES gathers the usual demographic data. The subjects also reported their history of cardiovascular disease (CVD), benign prostatic hypertrophy (BPH), prostate cancer, and physical activity. For men older than 20 years old, the overall prevalence of ED was 18.4% (approximately 18 million men). The prevalence increased with age (5.1% for 20-39 years olds, 14.8% for 40-59 years olds, 43.8% for 60-69 years old, and 70.2% for 70 years and older). Age-adjusted rates of ED for selected cardiovascular risk factors and prostate disease are listed in Table 1.
|Condition||Prevalence of ED|
|Body mass index > 30||20.3%|
|Vigorous physical activity||12.6%|
|Moderate physical activity||17.2%|
|No physical activity||23.3%|
|History prostate cancer||70.2%|
Conversely, ED is a risk factor for several diseases. For instance, diabetes was present in 30.9% of men with ED, but only 9.4% of men with no ED. In age-adjusted multivariate analysis, less than a high school education, current smoking status, BMI > 30, treated hypertension, diabetes, CVD history, and BPH history were all significantly associated with ED.
Ignoring the role of libido for the moment, getting an erection is a matter of hydraulics and the electricochemical system controlling the opening and closing of valves. Anything that disrupts blood flow or damages the neural system will cause ED. Most of the associations noted in this study are biologically plausible, and the root causes are vascular disease, secondary to smoking or the metabolic syndrome, and neuropathy (eg, diabetic) or mechanical nerve disruption (eg, radical prostatectomy). Age is certainly a factor, but may, in part, represent the time needed for repeated insults to accumulate. The authors did not report the incidence of ED associated with normal blood pressure, but the numbers for treated hypertension are high, and probably contribute to noncompliance with antihypertensive medications. The association with education is probably a marker for healthy behavior. The association with smoking is especially ironic, reminding me of the old vaudeville joke. "Do you smoke after sex?" "I don't know. I've never looked." Ba-da-bing!
This study's strengths are its large sample size and meticulous methodology. Its weakness is much of the data is self-reported. Its findings are similar to others. In a study of Canadian primary care patients, ED was diagnosed in 49.4% of men, but ED was defined differently from the current report. In this study, CVD and DM were also associated with ED, along with an increasing 10-year Framingham coronary risk score and fasting hyperglycemia. The Health Professionals Follow-up Study reported a prevalence of 33% with associations with obesity, smoking, sedentary lifestyle, alcohol consumption, and television viewing time. These may be more than mere associations; there is evidence to support lifestyle changes to prevent ED, including adherence to a Mediterranean diet and exercise.
ED is important in and of itself, because of the dis-stress it can cause a man and his partner. Importantly, it is a marker for serious and life-threatening diseases. We owe it to our patients to ask about ED and investigate the possible associations when we find it. Similarly, when we see men who have the metabolic syndrome or who smoke, we should ask about ED. If I were an obese, diabetic, hypertensive, 2-pack-a-day, couch potato, high school dropout who was having trouble "down there," I might look at these numbers and say, "Doc, I'm ready to lose weight, quit smoking, get my GED, and start an exercise program, but let's worry about my high blood pressure later." Of course, my physician, being a student of statistics, would point out to me that these are associations and do not prove cause and effect, but, hey, if you're that motivated, let's get going! Or, more likely, I'd ask for a sample of Viagra. Medication is easy; lifestyle change is not.
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