Erectile dysfunction is an early sign of cardiovascular troubles down the road, such as a stroke or heart attack.
The finding comes from an analysis of men, ages 55 and older, in the Prostate Cancer Prevention Trial, a prospective, randomized, blinded study that compared Proscar (finasteride) with placebo over a seven-year period.
Because of concerns about the effect of the study drug on sexual function, the trial researchers tracked erectile dysfunction throughout the seven-year study. Men in the study were also evaluated every three months for cardiovascular disease, as part of the study’s safety monitoring.
Analyzing the 9,457 men randomly assigned to placebo yielded "the first evidence, to our knowledge, of a strong association between erectile dysfunction and subsequent development of clinical cardiovascular events," Dr. Thompson and colleagues wrote.
Previous studies have suggested the link, they wrote, but did not prospectively monitor a population of asymptomatic, healthy men for the development first of erectile dysfunction and then of cardiovascular events.
They concluded that, "Erectile dysfunction is a harbinger of cardiovascular clinical events in some men."
When men present with erectile dysfunction, Dr. Thompson and colleagues said, physicians should undertake "diligent observation" with a view to intervention for cardiovascular risk factors.
For this analysis, the researchers found that, of the nearly 9,500 men in the placebo arm of the study:
· 85% (or 8,063) had no cardiovascular disease at the start of the study.
· Of those, 47% (or 3,816) reported some level of erectile dysfunction at baseline.
· Of the 4,247 men with no baseline erectile dysfunction, 57% had developed it by five years and 65% by seven years.
Such a high degree of erectile dysfunction both at baseline and later, may seem surprising, Dr. Thompson and colleagues say, but similar findings have been previously reported. The Massachusetts Male Aging Study reported in 1994 that, in a group of men ages 40 to 70, the probability of impotence was 52% and the rate tripled between 40 and 70, they noted.
In a multivariate analysis of only those men who developed erectile dysfunction during the Texas study, the researchers found:
· The risk of any cardiovascular event was significantly increased for men with erectile dysfunction; the hazard ratio was 1.25, with a 95% confidence interval ranging from 1.02 to 1.53.
· The risk of angina was significantly higher; the hazard ratio was 1.53, with a 95% confidence interval ranging from 1.03 to 2.28.
· The risk of stroke appeared to be higher but did not reach statistical significance; the hazard ratio was 1.70, with a 95% confidence interval ranging from 0.98 to 2.96.
When the researchers looked at prevalent and incident erectile dysfunction together, the pattern was similar but the hazard ratios were larger because the study population was almost doubled. Specifically:
· In an analysis adjusted to account for covariates, the hazard ratio for any cardiovascular event was 1.45, with a 95% confidence interval ranging from 1.25 to 1.69.
· The risk of transient ischemic attack was the largest; the hazard ratio was 1.92, with a 95% confidence interval ranging from 1.12 to 3.26.
· The hazard ratio for myocardial infarction was 1.50, with a 95% confidence interval ranging from 1.20 to 1.87.
· The risk for stroke became significant; the hazard ratio was 1.79, with a 95% confidence interval ranging from 1.15 to 2.80.
The study raises several questions, the researchers noted, including:
· Do cardioprotective interventions aimed at aging men reduce or delay onset of erectile dysfunction?
· Could the degree of erectile dysfunction serve as a surrogate measure of the efficacy of preventive interventions in cardiac disease?
JAMA. 2005;294:2996-3002. Thompson IM et al. Erectile Dysfunction and Subsequent Cardiovascular Disease.