Introduction: Erectile dysfunction and cardiovascular risk factors.

B most definitions, erectile dysfunction (ED) qualifies as an epidemic—a disease occurrence that significantly affects various population groups and that occurs in numbers in excess of normal expectancy.1,2 Before a National Institutes of Health (NIH) Consensus Conference published a definition of ED in 1993, it was among several conditions included under the umbrella term impotence. The condition is now defined as the inability to achieve or maintain an erection sufficient for satisfactory sexual performance.3 The Massachusetts Male Aging Study (MMAS), a community-based survey of men aged 40 to 70 years, has provided much of what is currently known about the prevalence of ED, its relation to aging, and its comorbidities.4 ED of some degree was reported by 52.0% of the 1,290 men in the MMAS sample: moderate ED was most frequent, at 25.2%; the frequency of minimal ED was 17.2%; and the frequency of complete ED was 9.6%.4 Projecting the survey’s results to the 1990 population (conducted from 1987 to 1989), it was predicted that 18 million men aged 40 to 70 years would have some degree of ED.4 The NIH Consensus Conference estimated in 1993 that if men with partial ED were included, the US prevalence would be 30 million men.3 Based on MMAS data, the incidence rate for the US population of white men aged 40 to 69 years has been estimated at 617,715 new cases of ED annually.5 Age was the strongest predictor of ED in the MMAS sample. The probability of complete ED tripled from 5% to 15% between 40 and 70 years of age, and the probability of moderate ED doubled, from 17% to 34%.4 The importance of ED, however, may be more as a harbinger of underlying disease than as a quality-of-life issue. Atherosclerotic vascular disease can account for almost 50% of the ED in men 50 years of age, but atherosclerosis may be only the starting point for more extensive damage.1 Patients with ED and severe atherosclerotic vascular disease show structural changes in corporal tissue that affect the physiology of erection at many levels. Atrophy and fibrosis of cavernosal tissue appear to be the most important of atherosclerosis-induced alterations, leading eventually to corporal venoocclusive dysfunction.6 Heart disease and 2 of its strongly associated risk factors, hypertension and low serum high-density lipoprotein (HDL) cholesterol, were significantly correlated with ED in the MMAS sample.4 The age-adjusted probability of complete ED was 39% in those with treated heart disease and 15% in those with treated hypertension, compared with 9.6% in the total sample.4 As HDL cholesterol decreased from 90 to 30 mg/dL, the probability of moderate ED increased from 6.7% to 25% in men aged 40 to 55 years, and the probability of complete ED increased from almost 0% to 16% in men aged 56 to 70 years.4 Among patients with hypertension, an unrelated survey found a 68.3% prevalence of various degrees of ED; 45% of that sample had severe ED, suggesting greater severity in men with hypertension than in the general population of men with ED.7 Antihypertensive medication, moreover, may exacerbate ED as a side effect. Although correlations did not reach statistical significance, patients treated with diuretics and -blockers tended to have the highest incidence of ED.7 Abundant evidence links diabetes and ED. Reported rates in men with diabetes range from 27.5% to 59%, depending on age and severity of disease.1 In the MMAS sample, men who reported treated diabetes had 3 times the age-adjusted probability of complete ED as did the total population—28% versus 9.6%.4 Psychosocial factors also have strong correlations with ED. Men who scored highest on depression measures had an almost 90% probability of moderate or complete ED compared with 25% for the least depressed.4 As with some antihypertensive agents, antidepressants may worsen the condition.1 Impaired sexual function has also been linked to deteriorating social and economic position, the latter indicated by a decrease in household income.8 Based on epidemiologic data and observations of shared risk factors among ED, depression, and cardioFrom the Division of Cardiovascular Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA; and Heart Institute, Division of Research, Good Samaritan Hospital, Los Angeles, California, USA. Robert A. Kloner, MD, PhD, is a consultant, speaker, and researcher for Bayer/GSK, Lilly ICOS, and Pfizer. Address for reprints: Robert A. Kloner, MD, PhD, Heart Institute, Good Samaritan Hospital, 1225 Wilshire Boulevard, Los Angeles, California 90017. E-mail: rkloner@goodsam.org.