Corona_EU Urology 18/03/2010 10:38 Page 74
Erectile Dysfunction
Figure 1: Peak Systolic Velocity as a Function of Body Mass Index
A
18
B
55
C
60
Adj. r=0.056
50
p<0.05
50
16
45
40
14 40
30
35
12
20
Basal PSV (cm/sec)
Dynamic PSV (%)
Adj. r=–0.157 Dynamic PSV (cm/sec)
30
Adj. r=–0.105
p<0.0001
10
10 25
p<0.0001
0
<25 30–34.9 ≥35 <25 30–34.9 ≥35 <25 30–34.9 ≥35
25–29.9 35–39.9 25–29.9 35–39.9 25–29.9 35–39.9
BMI (kg/m
2
) BMI (kg/m
2
) BMI (kg/m
2
)
A and B: Basal (flaccid conditions) and dynamic (after prostaglandin E1 stimulation) peak systolic velocity as a function of obesity class. Data are expressed as mean (95% confidence
interval). C: Prevalence of pathological peak systolic velocity (<35mc/s) as a function of obesity class. Data are derived from a consecutive series of 1,582 patients attending the Andrology
Unit at the University of Florence for sexual dysfunction between January 2001 and August 2009. BMI = body mass index; PSV = peak systolic velocity.
Baseline data from the Massachusetts Male Aging Study (MMAS) Figures 1A and B show similar results in a larger series of patients, the
failed to find any association between BMI and ED.
13
More recently, characteristics of which do not differ significantly from the previous
cross-sectional analysis of data from the National Health and sample. Figure 1C also shows that the percentage of men with altered
Nutrition Examination Survey,
14
involving 2,126 non-institutionalised PSV on dynamic penile colour Doppler ultrasound (PCDU) (<35cm/s)
men representative of the US adult male population, demonstrated an increased as a function of obesity class. After adjustment for age and
attenuated association between obesity and ED after adjustment for National Cholesterol Education Program Adult Treatment Panel III
cardiovascular risk factors. However, longitudinal studies have clearly (NCEP-ATPIII)-derived components for metabolic syndrome (including
demonstrated a direct association between these conditions at hypertension, hyperlipidaemia and high fasting glucose), both basal
baseline and the subsequent development of ED.
15,16
The Health and dynamic PSV were associated with:
Professionals Follow-up Study,
16
which included 22,086 US male
health professionals, showed this link clearly. Results after a 14-year age (adjusted r=-0.154 and -0.276 for basal and dynamic PSV,
follow-up study period showed that ED was most likely to occur in respectively; both p<0.0001);
men who were obese (odds ratio [OR] 1.7 [1.5–2]), who lived a diabetes (adjusted r=-0.078 and -0.073 for basal and dynamic PSV,
sedentary lifestyle (OR 0.7 [0.7–0.8]) and did little physical activity <2.7 respectively; both p<0.01); and
versus >32.6 metabolic equivalents (METs)/week. In addition, hypertension (adjusted r=-0.101 and -0.056 for basal and dynamic
prospective data from MMAS demonstrated that cigarette smoking PSV, respectively; both p<0.05).
and BMI significantly predicted the risk of developing ED, even after
controlling for confounding factors.
17,18
The association with BMI was lost. This confirms previous results.
21
Hence, from the authors’ data it can be seen that an impaired
However, the way in which obesity affects ED is not entirely clear. penile blood flow is more closely associated with obesity-related
Early endothelial dysfunction and impaired nitric oxide synthesis, co-morbidities than with obesity.
necessary for stimulating smooth-muscle relaxation and increasing
blood flow, which is in turn necessary for erection, have been Obesity is, in fact, often co-morbid with other conditions. Figure 2
considered the major associated pathogenetic issues.
11–12,19–20
The shows, in the same cohort of ED subjects as before, the associations
authors
21
recently confirmed this hypothesis in a large cross-sectional between obesity and several metabolic and cardiovascular
trial including 2,435 male patients seeking treatment at an outpatient parameters. The prevalence of hypertension is dramatically increased
clinic for sexual dysfunction between 2001 and 2007. All of the as a function of obesity class (see Figure 2A). Obesity is mainly
subjects were interviewed using the structured interview on ED associated with insulin resistance. Insulin induces sodium retention
(SIEDY), a 13-item list made up of three scales that identify and and increases the aldosterone-secreting effect of angiotensin II.
quantify pathogenetic determinants of ED. These scales are organic These effects are likely to promote a rise in blood pressure and an
(scale 1), relational (scale 2) and intrapsychic (scale 3).
22
The results of increase in the sensitivity of vessels to endogenous substances.
this study showed that obesity was significantly associated with Moreover, insulin is a known growth factor and is involved in
higher scores on the organic scale of ED, while there was no lipoprotein metabolism. Insulin resistance in the liver promotes
difference among relational or intra-psychic determinants. It was also increased small dense low-density lipoprotein (LDL) cholesterol, low
shown that as the severity of obesity increased, penile blood flow high-density lipoprotein (HDL) cholesterol, increased C-reactive
decreased. In particular, in a subset of subjects who underwent a proteins, plasminogen activator inhibitor-1 and fibrinogen. Together
penile Doppler ultrasound study, it was found that half of patients with with hyperglycaemia, these changes increase the risk of
morbid obesity had pathological penile blood flow (peak systolic cardiovascular diseases and hypertension.
23
velocity [PSV] <35cm/s after 10g of prostaglandin injection). It was
also found that both dynamic and even basal PSV decreased as a It was recently reported that hyperglycaemia could increase the
function of obesity classification. activity of the calcium-sensitising pathway of RhoA/ROCK in isolated
74 EUROPEAN UROLOGICAL REVIEW
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