were again found to have a risk ratio of 1.97 (95% CI
3.63) to develop ED adjusted for age and hyperten-
sive medication.
In Finland, a cohort of 1130 men aged 50
70 were
followed 10 years in a fashion similar to that done in
the Massachusetts Male Health Study and Olmstead
County survey. This study produced an odds ratio of
1.4 that, while similar to that of the two aforementioned
cohorts, did not reach statistical signi±cance (95% CI
2.2) (Shiri
et al.
, 2005). Further analysis found that
smokers who developed vascular disease had three times
the risk of developing ED compared to nonsmokers
without vascular disease (RR 3.2, 1.3
7.5). In contrast,
smokers without vascular disease had no increased risk
of ED (RR 1.0 CI 0.5
1.8) (Shiri
et al.
, 2006). These
data have also been the subject of a recent systematic
review, which compiled 8 case
control and cohort stu-
dies composed of 28 586 men (the majority of which
are from the Male Health Professions Study) creating a
pooled OR of 1.81 (95% CI 1.34
2.44) for smokers hav-
ing increased risk of developing erectile dysfunction
et al.
, 2013).
Smoking effects on ED are dose dependent
Cigarette smoking has been suggested to act with dose
dependency as a risk factor for heart disease as well as
ED. In the subgroup analysis of other larger studies, odds
ratios of patients who developed ED showed a signi±cant
difference when men smoked
10 cigarettes per day
et al.
, 2005). Among smokers, a positive but
nonsigni±cant trend towards increased ED occurred in
relation to daily cigarette intake (Chew
et al.
, 2009).
In a younger, less comorbid population, heavy smokers
20 cigarettes per day) had doubled the likelihood of
severe ED compared to those who smoked less (Natali
et al.
, 2005). Others have also noted that cumulative
smoking history was also a risk factor for ED. For exam-
ple, cumulative indices such as pack-years were related to
higher risk of ED. In this instance, Gades
et al.
found that a 29 pack-year history was responsible for a
signi±cantly increased risk for ED compared to a
pack-year history which carried with it the same risk as a
nonsmoker. In similar ±ndings, the Boston Area Commu-
nity Health Survey found that it was only at a threshold
of 20 pack-years where the OR for developing ED became
signi±cant (Kupelian
et al.
, 2007). However, an earlier
Vietnam Experience Study did not show such a dose rela-
tionship (Mannino
et al.
, 1994).
Overall, it appears that the cumulative dose of cigarette
exposure does predict for the odds of developing ED.
Examining the severity of the ED, current evidence
appears to suggest that heavy smoking causes more severe
ED that appears to be not reversible following smoking
Smoking and effects on other comorbidities in
men with ED
Cigarette smoking is also known to affect numerous other
comorbidities associated with ED. For example, athero-
sclerosis and cardiovascular disease are known to affect
erectile function by decreasing penile perfusion pressures,
resulting in increased time to maximal erection and
decreased rigidity during erection (Shabsigh
et al.
, 1991;
et al.
, 1999). Cigarette smoking is associated with
arteriogenic ED and is a component of the general pro-
cess of atherosclerosis (Shabsigh
et al.
, 1991; Sullivan
et al.
, 1999). Arterio-insuf±ciency also hinders erectile
function by decreasing penile perfusion pressures, result-
ing in increased times to maximal erection and decreased
rigidity during erection (Dean & Lue, 2005).
Diabetes also contributes to ED through both micro-
vascular and macrovascular damage (Maiorino
et al.
2014). Studies have shown that
50% of diabetics have
some degree of ED (Giuliano
et al.
, 2004; Thorve
et al.
2011). Furthermore, men with diabetes have a 3-fold
increase in risk for developing ED (Feldman
et al.
, 1994).
Among a group of 51 464 middle-aged and elderly Chi-
nese men, smokers were found to have a hazard ratio of
1.25 with regard to developing type 2 diabetes compared
to nonsmokers (Shi
et al.
, 2013). As such, not only does
cigarette smoking directly impact the physiologic mecha-
nisms of erectile function, but it also contributes to the
development of other medical conditions independently
associated with ED.
Effects of smoking cessation on erectile function
The current literature has yet to reach a consensus as to
the magnitude of the bene±ts for smoking cessation spe-
ci±cally with regard to ED. Indeed, in multiple cross-sec-
tional studies, former smokers (de±ned as having quit
1 year prior to the study) have an increased
risk of suffering from any form of ED compared to men
who have never smoked (Austoni
et al.
, 2005; Gades
et al.
, 2005; Bacon
et al.
, 2006). Former smokers have
also been shown to have increased risk compared to cur-
rent smokers, even when adjusted for age (Ghalayini
et al.
, 2010). However, the study was compromised due
to a small sample size and no data to describe total
smoking history or the presence of speci±c confounders
such as vascular disease (Ghalayini
et al.
, 2010). In a sep-
arate study that excluded patients with cardiovascular dis-
ease, former smokers had same signi±cantly increased risk
for ED as current smokers (He
et al.
, 2007). Thus, it
2014 Blackwell Verlag GmbH
, 1087–1092
J. R. Kovac
et al.
Smoking and male erectile function