PubMed | Google ScholarSee all References In comparison, a study of 132 patients evaluated by penile duplex ultrasonography after intracorporeal papaverine injection found that hypertension alone was not an independent risk factor for vasculogenic ED.34x34Shabsigh, R, Fishman, IJ, Schum, C, and Dunn, JK. Cigarette smoking and other vascular risk factors in vasculogenic impotence. Urology. 1991; 38: 227–231
A component of the increased risk conferred by ED could be testosterone deficiency.24 Low testosterone leads to increased levels of total and LDL cholesterol, as well as to increased production of pro-inflammatory markers and mediators.25 Endothelial dysfunction and increased arterial wall thickness, stiffening, and calcification also ensue. On this basis it has been hypothesized that chronically lowered testosterone may increase CVD risk. Indeed, androgen deficiency has emerged as a predictor of CV events, as well as of all-cause and CV mortality, both in the general population and in patients with CV risk factors, with hypertension, with established CVD, and with ED.26 Viewed from the opposite angle, higher serum testosterone showed a protective role for CV events in elderly men.27 A 2010 meta-analysis limited to studies in middle-aged men found no association between total testosterone (TT) levels and CVD risk.28 However, a more recent meta-analysis involving a larger number of studies identified significant associations between androgen deficiency and increased risk of CVD and CVD mortality.29 It should be stressed, however, that the nature of these studies cannot prove causality. The possibility that low testosterone may be an epiphenomenon, marking poor general health rather than modulating CVD risk per se has to be explored.
Erectile dysfunction carries an independent risk for cardiovascular events. A considerable number of studies have examined the ability of ED to predict the risk of future fatal and non-fatal cardiovascular events (myocardial infarction, stroke, revascularization) and total mortality in the general population and in high CV risk patients, in diabetics and in heart failure patients.5,19–22 In a meta-analysis of 14 prospective cohort studies involving 92 757 men followed for a mean period of 6.1 years (Figure 4), ED increased significantly and independently of traditional risk factors the risk of CV events, CV mortality, myocardial infarction, cerebrovascular events, and all-cause mortality by 44, 19, 62, 39, and 25% respectively.5 This predictive ability also extends in men with known CVD: ED increased the risk of all-cause mortality by 90%.5 Of importance, the predictive ability of ED is higher in younger ED patients5 despite the fact that probability of ED increases with age, most likely identifying a group of patients with early and aggressive vascular disease.23 Clinical implementation of ED as a biomarker relies on whether its addition on classical risk scores such as the Systematic COronary Risk Evaluation (SCORE) or the Framingham correctly reclassifies a meaningful percentage of patients into a higher or lower risk category. To this end, data are limited. Yet, in a population-based study of men 40–70 years of age, the addition of the ED status to the Framingham risk score resulted in a reclassification of 6.4% of low-risk patients to intermediate risk.19
Erectile dysfunction is a common occurrence in men with diabetes. The incidence of erectile dysfunction increases progressively with age, from 5% in men age 20 to 75% in men over age 65. The cause of erectile dysfunction in men with diabetes is usually related to a decrease in the blood supply to the penis as well as to injury to the nerves that are responsible for the erection mechanism. A decrease in testosterone production has also been identified as the cause in some men with diabetes.