The prevalence and predictors of erectile dysfunction in men with newly diagnosed with type 2 diabetes mellitus

Transcription

1 Original Article ERECTILE DYSFUNCTION IN DIABETICS AL-HUNAYAN et al. The prevalence and predictors of erectile dysfunction in men with newly diagnosed with type 2 diabetes mellitus Adel Al-Hunayan, Manal Al-Mutar, Elijah O. Kehinde, Lukman Thalib* and Mounir Al-Ghorory Departments of Surgery (Division of Urology) and *Community Medicine, Faculty of Medicine, Kuwait University and Ministry of Health, Primary care, Kuwait Accepted for publication 22 August 2006 OBJECTIVE To determine the prevalence of and risk factors for erectile dysfunction (ED) in men newly diagnosed with type 2 diabetes mellitus (DM). PATIENTS AND METHODS All consecutive samples of men newly diagnosed with type 2 DM attending the diabetes centre in the capital of Kuwait were included in the study. Face-to-face interviews with the men were conducted using the International Index of Erectile Function (IIEF)- 5 questionnaire. A threshold IIEF-5 score of <21 was used to identify men with ED. Pertinent clinical and laboratory characteristics were collected. RESULTS Of 323 men with newly diagnosed type 2 DM, 31% had ED; comparing potent men and men with ED, there were statistically significant differences for smoking, duration of smoking, hypertension, education level, body mass index and serum glycosylated haemoglobin level. Among these, age was the most important risk factor identified by multivariate logistic regression. CONCLUSION About a third of men with newly diagnosed type 2 DM had ED; this was associated with many variables, but most notably with age at presentation. KEYWORDS diabetes mellitus, erectile dysfunction, prevalence, risk factors, complications INTRODUCTION Type 2 diabetes mellitus (DM) is a common, serious disease leading to a risk of cardiovascular mortality that is two to four times that in people who do not have DM [1]. This higher risk is already present in newly diagnosed patients, and is one reason why screening is recommended for type 2 DM [2,3]. The risk is higher presumably because patients with type 2 DM have an asymptomatic phase between the onset of diabetic hyperglycaemia and clinical diagnosis that is estimated to last at least 4 7 years [4]. This untreated hyperglycaemia might explain the relatively high prevalence of microvascular complications (up to 48%) and macrovascular complications (up to 40%) in patients with newly diagnosed type 2 DM [4 6]. One common complication of type 2 DM is erectile dysfunction (ED) [7]. Under these conditions, ED is associated with a reduced quality of life [8], and occurs at an earlier age than in the general population [9]; it presents early in the course of the clinical disease and is occasionally the presenting problem [10,11]. Several studies examined the prevalence and predictors of ED in men with established type 2 DM [12 14], but we are not aware of any that addressed this issue in men newly diagnosed with type 2 DM. Early diagnosis and treatment of ED in such men might prevent or delay its progression and might improve the quality of life of these men. The aim of the present study was to estimate the prevalence and examine the risk factors for ED in men newly diagnosed with type 2 DM. PATIENTS AND METHODS The Diabetic Center of the Capital Governorate in Kuwait, where the study took place, serves all primary-care clinics in the governorate, and covers a catchment with a population of All patients found or suspected to have DM in these primary-care clinics are referred to this Center. In the Diabetic Center, from June 2004 to June 2005, those men found to have type 2 DM as defined below were included in the study. We also included men known to have type 2 DM diagnosed within 1 year from the time of the interview. In this way, 323 men with type 2 DM, aged years, were recruited. In accordance with WHO recommendations [15], type 2 DM was diagnosed when the following conditions were met: (i) for patients with no symptoms of hyperglycaemia, a fasting capillary whole-blood glucose measurement of 6.1 mmol/l or a fasting plasma glucose level (FPG) of 7.0 mmol/l on two separate occasions; (ii) for patients with symptoms of hyperglycaemia, one fasting capillary wholeblood glucose measurement of 6.1 mmol/l or one FPG of 7.0 mmol/l. All of the men were interviewed by an experienced diabetologist, following a protocol approved by the local ethical committee. After obtaining informed consent, the men were asked about their sex life; during the interview, the diabetologist explained the meaning of ED before asking whether they had experienced ED in the past 12 months. An abbreviated version of the International Index of Erectile Function (IIEF)- 5 [16] was administered to all men. Men with a score of 21 (range of score of 5 25) were considered to have ED. A personal and medical history was taken for each man. Risk factors such as age, education level, smoking habits, and nationality were assessed by direct questioning. Body mass index (BMI) was based on the weight within 3 months of diagnosis. Blood pressure was 2006 BJU INTERNATIONAL doi: /j x x 1

2 AL-HUNAYAN ET AL. calculated as the mean of two measurements taken while sitting after 5 min of rest. Men were considered hypertensive if they had a diastolic blood pressure of 90 mmhg, a systolic blood pressure of 140 mmhg, and/or were taking antihypertensive medications [17]. Serum total cholesterol was measured using enzymatic techniques. Hypercholesterolaemia was defined as a serum total cholesterol level of >6.2 mmol/l, while borderline hypercholesterolaemia was defined as a level of mmol/l. Income was recorded in the local currency and converted to US dollars. The glycosylated haemoglobin (HbA1c) percentage was determined by ion-exchange HPLC. Statistical analysis began with descriptive methods followed by tests of associations between ED and potential risk factors. As the predictor variables were categorical or grouped, chi-square tests, including the test for trend (when the predictor variables were ordinal), were used to examine the association between the risk of ED and individual risk factors. Odds ratios of ED associated with the predictor variables were computed using univariate and multivariate logistic regression. Multivariate logistic regression allowed the identification of the independent predictors that were significantly associated with ED; P < 0.05 was considered to indicate statistical significance. RESULTS Table 1 shows the medical and social characteristics of the men. Of 651 men newly diagnosed with type 2 DM, 305 refused to participate and 23 could not be screened because of hearing or vision impairment, thus 323 men participated in the study. They had a mean age of 41.7 years, and about a third were Kuwaiti nationals. Current smokers constituted 13.9% of the sample, and about a quarter had hypertension. The overall mean (SEM) prevalence of ED in the study population was 31 (0.26)%. The prevalence was significantly associated with age (P < 0.05); as shown in the chi-square test for trend. The prevalence increased with increasing age; men aged years had a prevalence of 63% compared to 11% among men aged years. The association of other risk factors with ED is shown in Tables 1 and 2. Compared to potent men, men with ED had significant differences TABLE 1 The medical and social characteristics of the study patients (323 men) according to presence of ED Diabetic men Variable All With no ED With ED P Number of men Mean (SEM) age, years 41.7 (0.6) 39.1 (0.6) 47.5 (1.0) <0.001* N (%): Age group, years; n, (%) <0.001 < (47.1) 133 (59.6) 19 (19.0) (33.7) 67 (30.0) 42 (42.0) >50 62 (19.2) 23 (37.1) 39 (39.0) Nationality 0.02 Kuwaiti 107 (33.1) 83 (37.2) 24 (24) Not Kuwaiti 216 (66.9) 140 (62.8) 76 (76) Monthly income, US $ 0.70 < (85.1) 191 (85.7) 84 (84) > (14.9) 32 (14.3) 16 (16) Education level <High school 128 (39.6) 100 (44.8) 28 (28) <0.001 High school 159 (49.2) 105 (47.1) 54 (54) >High school 36 (11.1) 18 (8.1) 18 (18) Current smoking <0.001 No 278 (86.1) 204 (91.5) 74 (74) Yes 45 (13.9) 19 (8.5) 26 (26) Mean (SEM) duration of smoking, 12.8 (0.9) (1.1) 9.47 (1.2) <0.001* pack years Mean (SEM) HbA1c, % 6.59 (0.05) 6.44 (0.07) 6.93 (0.08) <0.001* Mean (SEM) serum cholesterol, mmol/l 5.1 (0.04) 5.06 (0.05) 5.2 (0.07) 0.127* N (%): BMI, kg/m 2 < (57.6) 146 (65.5) 40 (40.0) < (34.1) 66 (29.6) 44 (44.0) >30 27 (8.4) 11 (4.9) 16 (16) Hypertension Yes 87 (26.9) 48 (21.5) 39 (39) No 236 (73.1) 175 (78.5) 61 (61) *t-test; chi-square test; chi-square test for trend for serum HbA1c level, current smoking habits, duration of smoking, BMI, nationality, and hypertension. The other risk factor that was significantly different between the groups was the education level, which was inversely related to the prevalence of ED (P = 0.003). There were no significant associations between monthly income, serum cholesterol level and the risk of ED. When multivariate logistic models were used to identify the independent predictors of the ED, four important risk factors were significantly and independently associated with ED (Table 2), the most important of which was age. Compared to men aged <40 years, men aged years had almost five times the risk of having ED, whilst men aged >50 years had nine times the risk. Current smoking, hypertension and BMI were all independently associated with ED. Smokers were almost three times more likely to have ED than non-smokers, and men with hypertension had twice the risk of having ED after adjusting for other important factors. Obese and overweight men had a greater risk of ED, (five times and twice, respectively) than men with a normal BMI. DISCUSSION While the prevalence of undiagnosed type 2 DM in ED has been reported [18], we are not aware of previous data in men with newly BJU INTERNATIONAL

3 ERECTILE DYSFUNCTION IN DIABETICS TABLE 2 Risk factors associated with ED quantified by univariate and multivariate logistic regression among 323 men with newly diagnosed type 2 DM Univariate logistic regression Multivariate logistic regression Risk Factor Frequency Crude OR (95% CI) P Adjusted OR (95% CI) P Age, years < Reference Reference ( ) < ( ) <0.001 > ( ) < ( ) <0.001 Nationality Kuwaiti 216 Reference Not Kuwaiti ( ) Education <High school 128 Reference High school ( ) 0.25 >High school ( ) 0.01 Monthly income, US $ < Reference > ( ) 0.74 Current smoking No 278 Reference Reference Yes ( ) < ( ) Hypertension No 236 Reference Reference Yes ( ) < ( ) BMI, kg/m Reference Reference ( ) < ( ) > ( ) < ( ) HbA1c, % <8 305 Reference > ( ) 0.03 Serum cholesterol, mmol/l < Reference ( ) 0.90 > ( ) 0.39 average Kuwaiti. Whereas most Kuwaitis have partners, most expatriates are living without partners, either by choice or because they cannot afford to bring their families with them to Kuwait, given their low salaries and high living expenses, hence they are not in a stable sexual relationship. These circumstances might explain why, after adjusting for age, expatriates were 1.8 times more likely to report ED than citizens (Table 2). Moreover, it is possible that most expatriates were not embarrassed by the questions, whereas locals are sensitive to sex-related queries, as it is a taboo in Islamic culture. Therefore, they might have reported their ED more faithfully. In the present study, unlike Western reports [22,25], men with a higher education level had higher risks of ED. We attribute this to probably greater stresses associated with the careers of the educated men. An association between smoking and risk of ED was reported [26]. This association might be due to the positive association of cigarette smoking with atherosclerosis, which itself is thought to be an important cause of early ED in men with diabetes [26]. In the present study there was also a greater risk of ED in smokers; among those who smoked, the mean duration of smoking was significantly higher in men with ED (Table 1). When adjusted for age, hypertension and BMI, smokers had more than three times the risk of ED (Table 2). Smoking was also shown to increase the risk of ED in nondiabetic men [27]. OR, odds ratio. diagnosed type 2 DM. In the present study, the prevalence of ED was 31% and it increased with age. The main determinants of risk were age, hypertension, smoking and BMI. Many studies report that the prevalence of ED in established diabetics is 20 75% [12 14,19 23]. These studies were conducted during different periods, in different settings and in populations with different mean ages, and might be difficult to compare with the present study. In addition, many of those studies showed a significant positive correlation between the prevalence and the duration of diabetes. Therefore, it is not surprising that the prevalence of ED in known diabetics tends to be higher than in newly diagnosed cases. The influence of age on the prevalence of ED is well established in normal men [24] and in men with known DM [9,22]. Advancing age was significantly correlated with a higher ED prevalence, as shown in Tables 1 and 2. Compared with similar age groups, the prevalence in the present study, as expected, is one of the lowest reported. The longer the duration of diabetes, the greater the chance of ED, supporting the aetiological significance of DM in the development of ED. Expatriates in Kuwait are mainly from the Indian subcontinent, Middle East or North Africa, and the vast majority are unskilled workers with salaries much lower than the Medical conditions such as hypertension, depression, cardiac disease and pelvic trauma or surgery can be associated with a greater risk of ED [25]. In hypertension, the relationship with ED is complex and might involve both the direct effects of elevated blood pressure and the effects of antihypertensive medication on the microcirculation [28]. In the present study, while adjusting for age, BMI and smoking, men with hypertension were twice as likely to report ED as those who were not hypertensive. This is consistent with the finding in Italian diabetic men where, while controlling for age and other risk factors, there was a 67% increase in the relative risk of ED in those who were hypertensive compared to those who were normotensive [29]. Although there was no significant association between monthly income and the risk of ED, this does not necessarily mean that income 2006 BJU INTERNATIONAL 3

4 AL-HUNAYAN ET AL. level is not related to ED. This is because we measured income level in two categories (< or >$1500). Most men earned <$1500, so the variability in income levels might not have been captured well. It is also possible that other factors related to income, such as smoking or hypertension, could confound the income-ed relationship. Elevated HbA1c end-products associated with hyperglycaemia in men with DM have been postulated to decrease nitric oxide activity and reduce endothelium-dependent relaxation factors associated with an increased risk of ED [23]. McCulloch et al. [30] found a positive association of poor glycaemic control and the 5-year incidence of ED in men with DM. Those findings support the present results where, compared to men with HbA1c levels of <8%, men with HbA1c levels of >8.1% were almost three times more likely to report ED. In the present study there was also a significant association between ED and BMI even after adjusting for other significant risk factors, indicating that BMI is independently related to ED. In addition, there was a significant linear trend that enabled us to refine this association to a suggestion that the proportion of men with ED increased with an increase in BMI. The study population consisted of newly diagnosed men referred to the diabetes centre in the Capital governorate. They might not represent all newly diagnosed diabetics, as other (albeit smaller) centres in the country treat DM. Most patients seen in this clinic are expatriates, and this might lead to underrepresentation of newly diagnosed men. Also, some newly diagnosed diabetics with more severe forms of ED might go directly to the governorate hospital for treatment, especially those with multiple medical problems, who will need ambulatory hospital care. Therefore, the present study might include some men with less severe comorbid medical conditions. Population-based studies would therefore be needed to estimate the true prevalence of ED in newly diagnosed diabetics in our community. The strengths of the present study were that this was an opportunity to analyse the prevalence of ED in men newly diagnosed with type 2 DM for the first time, and was conducted by direct interviews with the patients by an experienced full-time diabetologist. This should minimize patient misunderstanding of the questions, and obviate interobserver differences. In conclusion, ED appears to be common in men with newly diagnosed type 2 DM and its prevalence is affected by many factors, including age, hypertension, smoking and BMI. CONFLICT OF INTEREST None declared. REFERENCES 1 Kannel WB, McGee DL. Diabetes and cardiovascular disease. The Framingham study. JAMA 1979; 241: De Vegt F, Dekker JM, Stehouwer CD, Nijpels G, Bouter LM, Heine RJ. Similar 9-year mortality risks and reproducibility for the World Health Organization and American Diabetes Association glucose tolerance categories: the Hoorn Study. Diabetes Care 2000; 23: Engelgau MM, Narayan KM, Herman WH. Screening for type 2 diabetes. Diabetes Care 2000; 23: Kohner EM, Aldington SJ, Stratton IM et al. United Kingdom Prospective Diabetes Study, 30: diabetic retinopathy at diagnosis of non-insulin-dependent diabetes mellitus and associated risk factors. Arch Ophthalmol 1998; 116: Harris MI, Klein R, Welborn TA, Knuiman MW. Onset of NIDDM occurs at least 4 7 yr before clinical diagnosis. Diabetes Care 1992; 15: Spijkerman AM, Henry RM, Dekker JM et al. Prevalence of macrovascular disease amongst type 2 diabetic patients detected by targeted screening and patients newly diagnosed in general practice: the Hoorn Screening Study. J Intern Med 2004; 256: Melman A, Gingell JC. The epidemiology and pathophysiology of erectile dysfunction. J Urol 1999; 161: De Berardis G, Franciosi M, Belfiglio M et al; The Quality of Care and Outcomes in Type 2 Diabetes (QuED) Study Group. Erectile dysfunction and quality of life in type 2 diabetic patients: a serious problem too often overlooked. Diabetes Care 2002; 25: McCulloch DK, Campbell IW, Wu FC, Prescott RJ, Clarke BF. The prevalence of diabetic impotence. Diabetologia 1980; 18: Rubin A, Babbott D. Impotence and diabetes mellitus. J Am Med Assoc 1958; 168: Deutsch S, Sherman L. Previously unrecognized diabetes mellitus in sexually impotent men. JAMA 1980; 244: Yamasaki H, Ogawa K, Sasaki H et al. Prevalence and risk factors of erectile dysfunction in Japanese men with type 2 diabetes. Diabetes Res Clin Pract 2004; 66 (Suppl. 1): S Roth A, Kalter-Leibovici O, Kerbis Y et al. Prevalence and risk factors for erectile dysfunction in men with diabetes, hypertension, or both diseases: a community survey among 1412 Israeli men. Clin Cardiol 2003; 26: Cavan DA, Barnett AH, Leatherdale BA. Diabetic impotence: risk factors in a clinic population. Diabetes Res 1987; 5: Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care 1997; 20: Rosen RC, Cappelleri JC, Smith MD, Lipsky J, Pena BM. 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: World Health Organization- International Society of Hypertension. Guidelines for the management of hypertension. Guidelines Subcommittee. J Hypertens 1999; 17: Sairam K, Kulinskaya E, Boustead GB, Hanbury DC, McNicholas TA. Prevalence of undiagnosed diabetes mellitus in male erectile dysfunction. BJU Int 2001; 88: Giuliano FA, Leriche A, Jaudinot EO, de Gendre AS. Prevalence of erectile dysfunction among 7689 patients with diabetes or hypertension, or both. Urology 2004; 64: Nathan DM, Singer DE, Godine JE, Perlmuter LC. Non-insulin-dependent diabetes in older patients. Complications and risk factors. Am J Med 1986; 81: Feldman HA, Goldstein I, Hatzichristou DG, Krane RJ, McKinlay JB. Impotence and its medical and psychosocial correlates: results of the Massachusetts BJU INTERNATIONAL

5 ERECTILE DYSFUNCTION IN DIABETICS Male Aging Study. J Urol 1994; 151: Klein R, Klein BE, Lee KE, Moss SE, Cruickshanks KJ. Prevalence of selfreported erectile dysfunction in people with long-term IDDM. Diabetes Care 1996; 19: Brunner GA, Pieber TR, Schattemberg S et al. [Erectile dysfunction in patients with type I diabetes mellitus]. Wien Med Wochenschr 1995; 145: Martin CE. Factors affecting sexual functioning in year-old married males. Arch Sex Behav 1981; 10: Fedele D, Coscelli C, Santeusanio F et al. Erectile dysfunction in diabetic subjects in Italy. Gruppo Italiano Studio Deficit Erettile nei Diabetici. Diabetes Care 1998; 21: Virag R, Bouilly P, Frydman D. Is impotence an arterial disorder? A study of arterial risk factors in 440 impotent men. Lancet 1985; 26: Shabsigh R, Fishman IJ, Schum C, Dunn JK. Cigarette smoking and other vascular risk factors in vasculogenic impotence. Urology 1991; 38: Muller SC, el-damanhoury H, Ruth J, Luc TF. Hypertension and impotence. Eur Urol 1991; 19: Fedele D, Coscelli C, Cucinotta D et al. Incidence of erectile dysfunction in Italian men with diabetes. J Urol 2001; 166: McCulloch DK, Young RJ, Prescott RJ, Campbell IW, Clarke BF. The natural history of impotence in diabetic men. Diabetologia 1984; 26: Correspondence: Adel A. Al-Hunayan, Department of Surgery (Section of Urology), Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, Kuwait. alhunayan@gmail.com Abbreviations: ED, erectile dysfunction; DM, diabetes mellitus; FPG, fasting plasma glucose level; IIEF, International Index of Erectile Function; BMI, body mass index; HbA1c, glycosylated haemoglobin BJU INTERNATIONAL 5