The analyses are drawn from data collected during the longitudinal Massachusetts Male Aging Study, a population-based, prospective cohort study that enrolled 1,709 men who were 40 to 70 years old at the baseline visit (1987-1989). Information on erectile dysfunction and other aspects of sexual function were derived from a self-administered questionnaire. Data on CVD events were obtained through self-report, linkage with the National Death Index, and medical records.
The role of ED as a risk factor for future CVD was investigated in a subset of 1,057 men who at baseline had complete CVD risk factor data (age, body mass index, HDL and total cholesterol, smoking status, and blood pressure) and were free of CVD and diabetes (J Am Coll Cardiol 2010; 55:350-6). During a mean follow-up of 10.7 years, 261 men (25%) developed CVD.
A second paper (Am J Cardiol 2010; 105:192-7) considered the predictive value of aspects of sexual health beyond ED. The analyses adjusted for other risk factors, including ED and Framingham risk score, and were based on data from a mean follow-up of 16.2 years for 1,165 men who had complete ED data and were free of CVD at baseline. The results showed frequency of sexual activity was an independent predictor of CVD, with the risk being approximately 50% higher among men who had sexual activity once per month or less often compared to those who had sexual activity more than once per week.
Andre Araujo, PhD, director of epidemiology at New England Research Institutes and first author of the paper investigating ED as a CVD risk factor, observed that even though the presence of ED did not improve prediction of CVD beyond traditional risk factors, the ease of assessing for this problem suggests it may have adjunctive utility for CVD screening among men.
"Urologists and other health professionals should recognize that further workup for CVD is indicated when patients present with ED, as there may be a window of opportunity for men to improve their health before their first CVD event, which in some cases results in sudden death," Dr. Araujo told Urology Times. "Based on the accumulating evidence linking ED and CVD, we believe it is also important to raise public awareness so that men who notice a decline in erectile function will know to tell their physician."
Susan Hall, PhD, a research scientist at New England Research Institutes, was the lead author of the paper that associated sexual activity frequency and CVD risk.
"Previous prospective studies have shown that ED predicts CVD risk. What makes our findings novel is that this is the first study, to our knowledge, to have considered associations between a broader range of sexual function variables and subsequent CVD," she told Urology Times. "Given our longitudinal data, we thought it would be worthwhile to explore if aspects of sexual health 'upstream' from ED might be predictive of men's cardiovascular health and therefore present an even earlier opportunity to intervene.
"Screening for frequency of sexual activity in addition to erectile function is easy, and our findings suggest it may indicate the opportunity for an early point of intervention to improve a man's cardiovascular risk profile. However, other studies need to confirm whether or not frequency of sexual activity is truly a red flag for future CVD morbidity."
Further demographic studies needed
One limitation of the Massachusetts Male Aging Study is that the participants primarily comprise a cohort of Caucasian men (95%) with a high socioeconomic status. These demographic characteristics raise a question about whether the results could be generalized to other populations.
"While there is no reason to suspect that the association between ED and CVD would be different in any particular demographic group, we know that the prevalence of ED and CVD vary between subpopulations, so additional studies from other geographic regions or representing minority groups would be important," Dr. Araujo said.
The researchers postulated several explanations to account for why a lack of sexual activity might predict CVD, although they also pointed out there may be no direct causation.
"There are many possible reasons why this might be the case," Dr. Hall said. "One is that frequency of sexual activity might be a marker for overall health. As a physical activity, sexual activity might also be helping directly to protect against CVD, or men who are having regular sexual activity might also be more likely to be in a supportive intimate relationship with a regular partner and thereby derive stress reduction and social support benefits that would promote better health."
The investigators are continuing to examine the association between ED and CVD by conducting an in-depth clinical study of endothelial dysfunction, one of several hypothesized biological mechanisms shared by the two conditions.
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