Sage Journals: Discover world-class research

Abstract

Objective

To examine the relationship between risk factors for cardiac disease and erectile dysfunction (ED) in men from Xi’an, China.

Methods

Participants were patients with cardiovascular disease who visited the Cardiovascular Medicine Department of Xi’an Jiaotong University First Affiliated Hospital between September 2011 and March 2012. Two hundred and fifty patients were issued with questionnaires and underwent a physical examination and blood test.Risk factors for ED were identified using univariate and multivariate analyses.

Results

In total, 222 participants returned valid questionnaires (89% response rate), underwent a physical examination and blood test, and were included in the study. The most common cardiovascular diseases were hypertension (n = 142; 64%), coronary heart disease (n = 90; 41%) and angina pectoris (n = 78; 35%). Most patients (n = 144; 65%) had two or more cardiovascular diseases. Age, smoking, body mass index, total cholesterol level, hypertension and the ratio of total cholesterol to high-density lipoprotein cholesterol were significantly associated with ED. Domestic location, level of education, participation in physical activity, diabetes and drinking alcohol were not associated with ED.

Conclusions

Common risk factors for cardiovascular disease are associated with ED in patients with cardiovascular disease. This study furthers understanding of the risk factors for ED in Chinese patients with cardiovascular disease and paves the way for further research into the prevention of ED.

Keywords

Cardiovascular disease erectile dysfunction hypertension diabetes total cholesterol

Introduction

Cardiovascular diseases are diseases of the heart and vascular system¹ that have similar aetiologies, clinical development and general treatment principles.² A prospective, population-based, cohort study conducted between 1985 and 2009 found the mortality rate of male city residents due to cardiovascular disease was >34%.³ Internationally recognized major risk factors for cardiovascular disease include age, family history, smoking, obesity, unhealthy diet, lack of physical activity, dyslipidaemia, hypertension and diabetes.⁴ These are also significant risk factors for cardiovascular disease in a Chinese population.⁵

Erectile dysfunction (ED) is diagnosed when a man cannot reach or maintain a full erection and is unsatisfied with his sex life.⁶ Cardiovascular disease and ED often coexist, and they share common risk factors.⁷ In ED, the damage that occurs to the penile artery within the corpus cavernosum is the same as that which occurs in the cardiovascular or endothelial system in cardiovascular disease; thus, ED is a complication of cardiovascular disease or is secondary to arterial disease.⁸ The occurrence of ED is higher (31%) in patients with cardiovascular risk factors than in patients without cardiovascular risk factors (20%).⁹

The aim of this study was to examine the relationship between ED and risk factors associated with cardiovascular disease in men from Xi’an in China. This research provides data on the relationship of these interrelated diseases from a fast developing city in China.

Patients and methods

Patients

This study recruited patients with cardiovascular disease who visited the inpatient Department of Cardiovascular Medicine at the Xi’an Jiaotong University First Affiliated Hospital, Xi’an, China between September 2011 and March 2012. The study sample size and power were not predetermined as this was a time-specified study. All participants had at least one of the following cardiovascular diseases: hypertension (controlled by medication); coronary heart disease (diagnosed by cardiac catheterization study and treadmill); arrhythmia (confirmed by electrocardiogram); angina or myocardial infarction. All participants had normal thinking ability, independent judgement, clarity of thought, ability to answer questions and were willing to co-operate in the study. Patients were excluded if they abused alcohol, were diagnosed with a psychological disease including psychological ED, had high lactation hyperlipidaemia, primary gonadal syndrome, a pituitary tumour, bilateral or unilateral cryptorchidism, testicular inflammation, severe anaemia, a prostate tumour, a genital mutilation deformity, a spinal cord injury, urinary genital mutilation, sexual maldevelopment, sex hormone disease, thyroid disease, an endocrine system disease such as hyperthyroidism, systemic lupus erythematosus, a connective tissue disease, a malignant tumour, a blood system disease, severe liver or renal damage or a sexually transmitted disease. Patients were also excluded if they were critically ill or were unable to independently complete the investigation.

Study procedures

Participants answered a questionnaire, providing information on their age (18–35 years, 36–49 years, 50–65 years or >65 years), marital status, level of education, economic situation, lifestyle, occupation, family, smoking status, alcohol consumption, level of physical activity and medical history (presence of hypertension, diabetes, hyperlipidaemia, coronary artery disease, arrhythmia, peripheral vascular disease and cerebrovascular illness). All participants underwent a general examination at which blood pressure, height, weight, waist and hip circumference and other indicators were measured; routine blood and urine laboratory examinations were also performed to determine liver and kidney profile, total cholesterol level, ratio of total cholesterol to high-density lipoprotein (HDL) cholesterol, fasting plasma glucose level, random blood glucose level and blood glucose level 2 h after an oral glucose tolerance test. Body mass index (BMI) was calculated from height and weight data. Blood pressure was classified as normal, mild hypertension, moderate hypertension or severe hypertension according to the 2010 Guidelines for the Prevention and Treatment of Hypertension in China.¹⁰ Diabetes mellitus (DM) was diagnosed according to the American Diabetes Association¹¹ as a fasting plasma glucose ≥7.0 mmol/l, a random blood sugar ≥11.1 mmol/l or glucose ≥11.1 mmol/l 2 h after an oral glucose tolerance test.

Erectile dysfunction was diagnosed if patients reported that they were unable to reach the erectile level necessary to perform sexual intercourse or had difficulty maintaining an adequate erection, and were unable to attain a satisfactory sex life for ≥6 months prior to the date of diagnosis. As part of the questionnaire, participants completed the International Index of Erectile Function 5 (IIEF-5).¹² ED was classified as severe if the IIEF-5 score was ≤7, moderate if the IIEF-5 score was 8–11, moderate to mild if the IIEF-5 score was 12–16 and mild if the IIEF-5 score was 17–21.

Ethics statement

Before the study began, the Xi’an Jiaotong University Ethics Committee approved the study plan, the method of obtaining informed consent from all participants and the statement of written informed consent. The study met all ethical principles for medical research involving human participants and did not invade the patients’ privacy. Written informed consent was obtained from all participants and all participants were provided with free access to the study results.

Statistical analyses

Statistical analyses were performed on the obtained data to calculate the significance of risk factors of cardiovascular disease on ED. Odds ratio and 95% confidence intervals for ED was calculated using Statistical Package for Social Sciences (SPSS® version l3.0; SSPS Inc, Chicago, IL, USA) software for univariate and multivariate analyses. Statistical significance was defined as a P-value <0.05.

Results

In total, 250 patients were enrolled in the study and issued with a questionnaire. Valid, completed questionnaires were recovered from 222 patients, giving a response rate of 89%. Twenty-two respondents (10%) were aged 18 – 35 years, 69 (31%) were aged 36 – 49 years, 73 (33%) were aged 50 – 65 years, and 58 (26%) were aged >65 years. The prevalence of cardiovascular disease was lower in the 18 – 35 year age group than in any other age group. Hypertension was the most prevalent cardiovascular disease (present in 142 of 222 patients; 64%), followed by coronary heart disease (90 of 222 patients; 41%) and angina pectoris (78 of 222 patients; 35%) (Figure 1). Over half of all patients (144; 65%) had more than one cardiovascular disease (n = 80 had two diseases and n = 64 had more than two diseases). The prevalence of hypertension and ED significantly increased with age (Tables 1, 2 and 3).

Figure 1.

Distribution of individual cardiovascular diseases in male inpatients in the Department of Cardiovascular Medicine (Xi’an Jiaotong University First Affiliated Hospital, Xi’an, China), participating in a study examining the relationship between erectile dysfunction and risk factors for cardiovascular disease.

Table 1.

Distribution of hypertension classification¹⁰ according to age group in inpatients at the Department of Cardiovascular Medicine (Xi’an Jiaotong University First Affiliated Hospital, Xi’an, China), participating in a study examining the relationship between erectile dysfunction and risk factors for cardiovascular disease who completed the erectile dysfunction questionnaire and examinations.

Age group, years	Normal blood pressure	Hypertension
Age group, years	Normal blood pressure	Mild	Moderate	Severe
18–35	15	5	2	0
36–49	44	17	6	2
50–65	14	43	15^a	2
>65	7	17	30^a	3

Contingency table Χ² analysis; P < 0.0001.

Table 2.

Classification of erectile dysfunction¹² according to age in inpatients at the Department of Cardiovascular Medicine (Xi’an Jiaotong University First Affiliated Hospital, Xi’an, China).

Age group, years	Erectile dysfunction
Age group, years	None	Mild	Mild-to-moderate	Moderate	Severe
18–35	19	3	0	0	0
36–49	42	17	7	2	1
50–65	8	15	35^a	12^a	4
>65	5	0	18^a	25^a	9^a

Contingency table Χ² analysis; P < 0.0001.

Table 3.

Distribution of erectile dysfunction (ED) classifications by hypertension diagnosis in inpatients at the Department of Cardiovascular Medicine (Xi’an Jiaotong University First Affiliated Hospital, Xi’an, China).

Blood pressure	Erectile dysfunction
Blood pressure	None	Mild	Mild-to-moderate	Moderate	Severe
Normal blood pressure	40 (50.0)	10 (12.5)	15 (18.8)	13 (16.3)	2 (2.5)
Mild hypertension	25 (30.5)	17 (20.7)	23 (28.0)	10 (12.2)	7 (8.5)
Moderate hypertension	8 (15.1)	8 (15.1)	19(35.8)^a	15(28.3)^a	3 (5.7)
Severe hypertension	1 (14.3)	0 (0.0)	3 (42.9)	1 (14.3)	2 (28.6)

Data expressed as n (%) of patients.

Contingency table Χ² analysis; P < 0.0009.

Univariate logistic regression analysis showed that age (odds ratio [95% confidence interval, CI]) 3.12 (2.04, 4.78); BMI 1.26 (1.11, 1.43); hypertension 1.72 (1.11, 2.66); coronary artery disease 2.24 (1.17, 4.28); total cholesterol level 1.77 (1.34, 2.34); ratio of total cholesterol to HDL cholesterol 1.72 (1.35, 2.18) and smoking 1.77 (1.20, 2.58) were significantly associated with increased odds of ED (Table 4). Residence, level of education, physical activity, alcohol consumption and DM were not significantly associated with ED. Multivariate logistic regression analysis confirmed that age, smoking, BMI, economic situation and the ratio of total cholesterol to HDL cholesterol were independent risk factors for ED (Table 5).

Table 4.

Univariate logistic regression analysis of the relationship between erectile dysfunction and risk factors for hypertension in inpatients at the Department of Cardiovascular Medicine (Xi’an Jiaotong University First Affiliated Hospital, Xi’an, China).

Factor	Parameter	Standard error	Wald effect	Statistical significance	OR	95% CI
Factor	Parameter	Standard error	Wald effect	Statistical significance	OR	Lower	Upper
Age	1.14	0.21	27.48	P < 0.001	3.12	2.04	4.78
Constant	−0.64	0.37	2.92	0.05	0.52
Family	0.58	0.35	2.82	NS	1.79	0.91	3.52
Constant	0.31	0.60	0.28	0.60	1.37
Education level	0.00	0.23	0.00	NS	1.00	0.63	1.58
Constant	1.29	0.57	5.11	0.02	3.64
Physical activity	0.15	0.23	0.40	NS	1.16	0.74	1.82
Constant	1.06	0.41	6.82	0.01	2.88
Smoking	0.57	0.19	8.65	P < 0.003	1.77	1.21	2.58
Constant	0.55	0.29	3.61	0.06	1.73
BMI	0.23	0.06	13.42	P < 0.001	1.26	1.11	1.43
Constant	−4.12	1.47	7.92	0.005	0.05
High blood pressure	0.54	0.22	5.89	P = 0.015	1.71	1.11	2.66
Constant	0.93	0.21	19.55	0.00	2.53
Coronary disease	0.80	0.33	5.91	P = 0.015	2.24	1.17	4.28
Constant	0.97	0.20	24.16	0.00	2.65
Arrhythmia	0.26	0.32	0.67	NS	1.30	0.69	2.43
Constant	1.21	0.18	43.22	0.00	3.35
TC	0.57	0.14	16.06	P < 0.001	1.77	1.34	2.34
Constant	−0.16	0.32	0.23	0.63	0.86
TC/HDL	0.54	0.12	19.35	P < 0.001	1.72	1.35	2.18
Constant	−0.15	0.30	0.24	0.62	0.86

OR, odds ratio; CI, confidence interval; BMI, body mass ratio; TC, total cholesterol, HDL, high density cholesterol; NS, not significant.

Table 5.

Multivariate logistic regression analysis of the relationship between erectile dysfunction and risk factors for hypertension in inpatients at the Department of Cardiovascular Medicine (Xi’an Jiaotong University First Affiliated Hospital, Xi’an, China).

Factor	Parameter	Standard error	Wald effect	Statistical significance	OR	OR 95% CI
Factor	Parameter	Standard error	Wald effect	Statistical significance	OR	Lower	Upper
BMI	0.35	0.11	9.62	P = 0.002	1.41	1.14	1.76
Age	1.61	0.40	15.90	P < 0.001	4.99	2.26	11.00
TC	−0.05	0.25	0.04	NS	0.95	0.58	1.56
TC/HDL	0.69	0.35	4.02	P = 0.045	2.00	1.02	3.94
Smoking	0.75	0.30	6.33	P = 0.012	2.11	1.18	3.77
Occupation	0.15	0.29	0.26	NS	1.16	0.66	2.05
Family	−1.17	0.74	2.48	NS	0.31	0.07	1.33
Level of education	−0.61	0.47	1.71	NS	0.54	0.22	1.36
Economic situation	1.03	0.47	4.91	P = 0.027	2.80	1.13	6.98
Physical activity	0.36	0.42	0.73	NS	1.43	0.63	3.25
High blood pressure	−0.15	0.33	0.19	NS	0.87	0.45	1.66
Diabetes mellitus	−0.09	0.29	0.09	NS	0.92	0.52	1.63
Coronary disease	0.42	0.47	0.79	NS	1.52	0.60	3.83
Arrhythmia	−0.37	0.49	0.56	NS	0.69	0.26	1.81

OR, odds ratio; CI, confidence interval; TC, total cholesterol, HDL, high density cholesterol; NS, not significant.

Discussion

This study was performed in men with cardiovascular disease, attending the First Affiliated Hospital of Xi’an Jiaotong University. The data obtained from hospitalized patients have high stability and accuracy, thus the use of hospitalized patients is an effective way to avoid information bias.¹³ In addition, standardized survey processes were used, with uniform diagnostic criteria and reliable data filtering to reduce the risk of mixed bias and to increase the validity of these results.

A previous report suggested that the incidence of ED in patients with cardiovascular disease was similar in urban and rural areas.¹⁴ With the ongoing development of the Chinese economy, the difference between urban and rural areas will continue to decrease, and cardiovascular disease will no longer be a ‘rich man’s disease’ specific to economically developed regions or cities.¹⁵ A further study used multivariate logistic regression analysis to indicate that economic situation was an independent risk factor for ED in patients with cardiovascular disease.¹⁶ People across China now have reasonable standards of living and leisure, and an increasing intake of high protein, high cholesterol foods, but undertake less physical activity. A low level of physical exercise, obesity and high blood cholesterol are all risk factors for ED.¹⁷

As societies develop, the average lifespan increases,¹⁸ and the health-related quality of life as individuals age becomes of increasing concern.¹⁹ ED shows a close relationship with old age.²⁰ The perception among the general population is that as people age, decline in sexual function is a natural phenomenon. Although the news media provide excessive publicity about treatments available for sexually related diseases and sexual dysfunction, individuals who experience a decline in sexual function are embarrassed to seek medical help.²¹

In this study, most of the participants had at least two types of cardiovascular disease and a number of factors contributing to ED.²² The prevalence of ED increased with age, supporting previous reports that the prevalence of ED is higher in individuals aged ≥50 years than in individuals aged ≤50 years.²³ Univariate and multivariate logistic regression analyses showed that age was a risk factor for ED. This supports previous studies in China and abroad, such as the Zhang Qingjiang survey of 2,226 men in three cities in China, which reported that the prevalence of ED was 15.6% in men aged ≤30 years, 24.5% in those aged 3 l–40 years, 26.1% in those aged 51–60 years, 43.4% in those aged 61–70 years and 65.3% in those aged >70 years.²⁴

Smoking is a major risk factor for cardiovascular disease²⁵ and the incidence of hypertension, coronary heart disease and myocardial infarction is markedly higher in smokers than in nonsmokers.²⁶ Nicotine causes vascular endothelial dysfunction, reduces sex hormone secretion, increases dysfunction of sperm, reduces the grade-b sperm count, causes abnormal sperm morphology and reduced motility, resulting in infertility.²⁷ Smoking also affects blood circulation and reduces genital blood flow, which can lead to sexual dysfunction.²⁸ Results from the present study indicate that smoking was an independent risk factor for ED. This is consistent with the results of existing research results in China and abroad. A meta-analysis by Tengs and Osgood showed that smoking was an important factor in ED,²⁹ and the Zhang Qingjiang study reported that the incidence of ED was 42.3% in individuals who smoked >20 cigarettes/day.²⁴ In this study, no statistically significant relationship was found between alcohol consumption and ED, which supports the report of Nicolosi et al.³⁰

Obesity increases the risk of cardiovascular disease and can also affect the function of the endocrine system.³¹ BMI is a simple height-to-weight ratio, which, with the body fat percentage content, has major relevance to CHD.³² Obesity is an independent risk factor for coronary heart disease and stroke,^33,34 and a BMI ≥ 24 increases the risk of coronary heart disease in patients with high blood pressure, diabetes and dyslipidaemia.³⁵ Here, BMI was significantly associated with ED in patients with cardiovascular disease. There are several mechanisms by which obesity may increase the risk of ED. The high blood pressure, high blood sugar and high blood cholesterol associated with obesity will accelerate the formation of atherosclerotic plaques, which will have an effect on penile artery endothelium and blood flow dynamics.³⁶ Endocrine factors, such as reduced testosterone ketone secretion, and increased female hormone secretion can also impact ED.³⁷ Obesity can also cause psychological inferiority and lead to poor social adjustment, which can cause psychological obstacles to sexual performance. In addition, a large amount of fat in the abdominal area and around the fat pad at the base of the penis can be an obstacle to sexual performance.³⁸

Studies on the relationship between metabolism of blood lipids and erectile function are common both in China and in other countries.³⁹ Gholami et al.⁴⁰ concluded that hyperlipidaemia not only affects the vascular smooth muscle tissue of the penis, but also affects the peripheral cavernous nerve. Seftel et al.⁴¹ reported that between 1995 and 2002, 42.4% of ED patients in the USA had hyperlipidaemia-related ED. A decrease in high density lipoprotein an elevation of total cholesterol/HDL are both correlated with ED⁴² and are important risk factors for ED.⁴³ Results of the present study further indicate that the ratio of total cholesterol to HDL cholesterol is a risk factor for ED.

Hypertension may also be caused by mental and neurological factors,⁴⁴ problems with the renin-angiotensin system,⁴⁵ sodium retention (which leads to increased extracellular water and increased heart output volume),⁴⁶ or genetic factors.⁴⁷ Results of the present study showed that 76.1% of patients with essential hypertension had ED and that hypertension was a risk factor for ED.

Univariate logistic regression analysis showed that DM was not significantly associated with ED, which may have been due to the good control of blood sugar levels by the patients with DM involved in this study.

One limitation of this study was that the sample size and power were not predetermined.

In conclusion, this study confirms that risk factors for cardiovascular disease, i.e. economic situation, smoking, hypertension, coronary heart disease, diabetes and total cholesterol are also risk factors for ED. This study furthers our understanding of the risk factors for ED in Chinese patients with cardiovascular disease and paves the way for further research regarding prevention of ED.

Footnotes

Declaration of conflicting interest

The authors had no conflicts of interest to declare in relation to this article.

Funding

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

References

Grundy

Brewer

Jr Cleeman

. Definition of metabolic syndrome: report of the national heart, lung, and blood institute/American heart association conference on scientific issues related to definition. Circulation 2004; 109: 433–438.

Miura

Daviglus

Dyer

. Relationship of blood pressure to 25-year mortality due to coronary heart disease, cardiovascular diseases, and all causes in young adult men: the Chicago heart association detection project in industry. Arch Intern Med 2001; 161: 1501–1508.

Lakka

Laaksonen

Lakka

. The metabolic syndrome and total and cardiovascular disease mortality in middle-aged men. JAMA 2002; 288: 2709–2716.

Van Gaal

Rissanen

Scheen

. Effects of the cannabinoid-1 receptor blocker rimonabant on weight reduction and cardiovascular risk factors in overweight patients: 1-year experience from the RIO-Europe study. Lancet 2005; 365: 1389–1397.

Sung

Choi

. Waist circumference and body mass index in Chinese children: cutoff values for predicting cardiovascular risk factors. Intern J Obes (London) 2006; 31: 550–558.

Lue

. Erectile dysfunction. N Engl J Med 2000; 342: 1802–1813.

Thompson

Tangen

Goodman

. Erectile dysfunction and subsequent cardiovascular disease. JAMA 2005; 294: 2996–3002.

Billups

Bank

Padma-Nathan

. Erectile dysfunction is a marker for cardiovascular disease: results of the minority health institute expert advisory panel. J Sex Med 2005; 2: 40–50. discussion 50–42.

Kirby

Jackson

Betteridge

. Is erectile dysfunction a marker for cardiovascular disease? Int J Clin Pract 2001; 55: 614–618.

10.

Liu

. Writing Group of 2010 Chinese Guidelines for the Management of Hypertension. [2010 Chinese guidelines for the management of hypertension]. Zhonghua Xin Xue Guan Bing Za Zhi 2011; 39: 579–615. [in Chinese, English Abstract].

11.

American Diabetes Association. The American Diabetes Association (ADA) has been actively involved in the development and dissemination of diabetes care standards, guidelines, and related documents for many years. Introduction. Diabetes Care 2009; 32(Suppl 1): S1–S2.

12.

Rosen

Cappelleri

Smith

. Development and evaluation of an abridged, 5-item version of the International Index of Erectile Function (IIEF-5) as a diagnostic tool for erectile dysfunction. Int J Impot Res 1999; 11: 319–326.

13.

Guan

Xue

Dai

. Down-regulation of survivin expression by small interfering RNA induces pancreatic cancer cell apoptosis and enhances its radiosensitivity. World J Gastroenterol 2006; 12: 2901–2907.

14.

Akkus

Kadioglu

Esen

. Prevalence and correlates of erectile dysfunction in Turkey: a population-based study. Eur Urol 2002; 41: 298–304.

15.

Naughton B. The Chinese economy: Transitions and growth. MIT Press Books (Cambridge, Massachusetts), 2007; p 1.

16.

Lewis

Fugl-Meyer

Bosch

. Epidemiology/risk factors of sexual dysfunction. J Sex Med 2004; 1: 35–39.

17.

Derby

Mohr

Goldstein

. Modifiable risk factors and erectile dysfunction: can lifestyle changes modify risk? Urology 2000; 56: 302–306.

18.

Aísa

Pueyo

. Endogenous longevity, health and economic growth: a slow growth for a longer life? Economics Bulletin 2004; 9: 1–10.

19.

Hellström

Hallberg

. Perspectives of elderly people receiving home help on health, care and quality of life. Health Soc Care Community 2001; 9: 61–71.

20.

Johannes

Araujo

Feldman

. Incidence of erectile dysfunction in men 40 to 69 years old: longitudinal results from the Massachusetts male aging study. J Urol 2000; 163: 460–463.

21.

Benbadis

. The problem of psychogenic symptoms: is the psychiatric community in denial? Epilepsy Behav 2005; 6: 9–14.

22.

Kang

Izumo

. Apoptosis in heart: basic mechanisms and implications in cardiovascular diseases. Trends Mol Med 2003; 9: 177–182.

23.

Braun

Sommer

Haupt

. Lower urinary tract symptoms and erectile dysfunction: co-morbidity or typical “aging male” symptoms? results of the “cologne male survey”. Eur Urol 2003; 44: 588–594.

24.

Zhang

Zhu

. Male sexual function study in three Chinese cities on 2226 males. Chin J Androl 2003; 17: 191–193.

25.

Ridker

. High-sensitivity C-reactive protein: potential adjunct for global risk assessment in the primary prevention of cardiovascular disease. Circulation 2001; 103: 1813–1818.

26.

Yusuf

Hawken

Ounpuu

. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet 2004; 364: 937–952.

27.

Arabi

. Nicotinic infertility: assessing DNA and plasma membrane integrity of human spermatozoa. Andrologia 2004; 36: 305–310.

28.

Feldman

Johannes

Derby

. Erectile dysfunction and coronary risk factors: prospective results from the Massachusetts male aging study. Prev Med 2000; 30: 328–338.

29.

Tengs

Osgood

. The link between smoking and impotence: two decades of evidence. Prev Med 2001; 32: 447–452.

30.

Nicolosi

Moreira

Jr Shirai

. Epidemiology of erectile dysfunction in four countries: cross-national study of the prevalence and correlates of erectile dysfunction. Urology 2003; 61: 201–206.

31.

Yusuf

Hawken

Ounpuu

. Obesity and the risk of myocardial infarction in 27, 000 participants from 52 countries: a case-control study. Lancet 2005; 366: 1640–1649.

32.

Ogden

Carroll

Flegal

. High body mass index for age among US children and adolescents, 2003–2006. JAMA 2008; 299: 2401–2405.

33.

Freedman

Khan

Dietz

. Relationship of childhood obesity to coronary heart disease risk factors in adulthood: the Bogalusa heart study. Pediatrics 2001; 108: 712–718.

34.

Malik

Wong

Franklin

. Impact of the metabolic syndrome on mortality from coronary heart disease, cardiovascular disease, and all causes in United States adults. Circulation 2004; 110: 1245–1250.

35.

Rexrode

Buring

Manson

. Abdominal and total adiposity and risk of coronary heart disease in men. Int J Obes Relat Metab Disord 2001; 25: 1047–1056.

36.

Yudkin

Kumari

Humphries

. Inflammation, obesity, stress and coronary heart disease: is interleukin-6 the link? Atherosclerosis 2000; 148: 209–214.

37.

Pitteloud

Hardin

Dwyer

. Increasing insulin resistance is associated with a decrease in Leydig cell testosterone secretion in men. J Clin Endocrinol Metab 2005; 90: 2636–2641.

38.

Carr

Friedman

. Is obesity stigmatizing? body weight, perceived discrimination, and psychological well-being in the United States. J Health Soc Behav 2005; 46: 244–259.

39.

Boyanov

Boneva

Christov

. Testosterone supplementation in men with type 2 diabetes, visceral obesity and partial androgen deficiency. Aging Male 2003; 6: 1–7.

40.

Gholami

Rogers

Chang

. The effect of vascular endothelial growth factor and adeno-associated virus mediated brain derived neurotrophic factor on neurogenic and vasculogenic erectile dysfunction induced by hyperlipidemia. J Urol 2003; 169: 1577–1581.

41.

Seftel

Sun

Swindle

. The prevalence of hypertension, hyperlipidemia, diabetes mellitus and depression in men with erectile dysfunction. J Urol 2004; 171(6 Pt 1): 2341–2345.

42.

Rao

Yang

. [Hyperlipidemia and erectile dysfunction]. Zhonghua Nan Ke Xue 2006; 12: 643–646. [in Chinese, English Abstract].

43.

Roumeguere

Wespes

Carpentier

. Erectile dysfunction is associated with a high prevalence of hyperlipidemia and coronary heart disease risk. Eur Urol 2003; 44: 355–359.

44.

Dhalla

Temsah

Netticadan

. Role of oxidative stress in cardiovascular diseases. J Hypertens 2000; 18: 655–673.

45.

Mogensen

Neldam

Tikkanen

. Randomised controlled trial of dual blockade of renin-angiotensin system in patients with hypertension, microalbuminuria, and non-insulin dependent diabetes: the candesartan and lisinopril microalbuminuria (CALM) study. BMJ 2000; 321: 1440–1444.

46.

Obarzanek

Proschan

Vollmer

. Individual blood pressure responses to changes in salt 6intake: results from the DASH-Sodium trial. Hypertension 2003; 42: 459–467.

47.

Wolf-Maier

Cooper

Banegas

. Hypertension prevalence and blood pressure levels in 6 European countries, Canada, and the United States. JAMA 2003; 289: 2363–2369.

Risk factors for erectile dysfunction in patients with cardiovascular disease

Abstract

Objective

Methods

Results

Conclusions

Keywords

Introduction

Patients and methods

Patients

Study procedures

Ethics statement

Statistical analyses

Results

Discussion

Footnotes

Declaration of conflicting interest

Funding

References