with age , men experience decreases in important health indicators like muscle amount , physical activity , and sexual drive . furthermore , lower urinary tract symptoms ( luts ) are highly prevalent in males , and it has been clearly shown that the prevalence of luts increases with age . the incidence of erectile dysfunction ( ed ) also increases with age , as does the incidence of cardiovascular disease risk factors , such as hypertension , obesity , and diabetes . additionally , ed has a significant negative impact on quality of life ( qol ) . satisfaction with sexual life and the existence of luts severely affect men 's qol and plague middle - aged men 's health . numerous studies have assessed qol in men with luts , benign prostatic hyperplasia ( bph ) , and ed , but an estimation of middle - aged men 's health in comparison to other comprehensive clinical parameters has not been reported previously in korea . questionnaires are one of the most commonly used techniques for collecting health - related information in clinical studies because of their ease and simplicity . the international prostate symptom score ( ipss ) questionnaire is used worldwide to measure luts . to evaluate various voiding symptoms , perineal or suprapubic pain , and sexual disturbance , the national institutes of health chronic prostatitis symptom index ( nih - cpsi ) is used to assess chronic prostatitis ( cp)/chronic pelvic pain syndrome . the androgen deficiency in aging males ( adam ) , premature ejaculation diagnostic tool ( pedt ) , and internal index of erectile function-5 ( iief-5 ) questionnaires are used worldwide to evaluate men 's sex lives . by using these five questionnaires to evaluate detailed clinical problems , we proposed to research several factors affecting middle - aged men 's general health . we evaluated the relationship of various clinical parameters that are related to men 's general health and the symptom scores of five widely used questionnaires for detecting men 's health problems . we determined the predictive abilities of two obesity indexes and other clinical parameters for screening for luts and sexual dysfunction in middle - aged men . we believe that this study may not only provide a clearer figure of the suffering caused in middle - aged men 's qol , but also widen the public 's understanding of middle - aged men 's general health . between march and september 2013 , a total of 1910 healthy korean men aged 40 to 59 years who participated in a health examination were included . all men underwent detailed clinical evaluations by use of the ipss , nih - cpsi , adam , iief-5 , and pedt questionnaires . blood and urine samples were obtained for serum prostate - specific antigen ( psa ) and testosterone measurement between 0700 and 0900 . the estimated glomerular filtration rate ( egfr ) was calculated and metabolic syndrome ( mets ) was evaluated . the egfr was calculated by using the abbreviated four - variable modification of diet in renal disease equation : gfr=186.3(serum creatinine)-1.154(age)-0.203(0.742 if female)(1.210 if black ) mets was defined by using the criteria established by the national cholesterol education program - adult treatment panel iii published in 2005 . mets was diagnosed when at least three of the following criteria were present : ( 1 ) waist circumference greater than 90 cm or body mass index ( bmi ) higher than 25 kg / m , ( 2 ) systolic blood pressure 130 mmhg or greater or diastolic blood pressure 85 mmhg or greater or use of antihypertensive medication , ( 3 ) fasting blood sugar greater than 110 mg / dl or self - reported diabetes medication use , ( 4 ) triglyceride greater than 150 mg / dl , and ( 5 ) high - density lipoprotein cholesterol less than 45 mg / dl or use of lipid medication . thereafter , all of the participants underwent a digital rectal examination ( dre ) to screen for prostate enlargement or nodules suggesting prostate cancer . next , transrectal ultrasound ( trus ) was performed and ultrasonographic inspection of the prostate was performed in each subject by using a 3.5-mhz transducer ( voluson 730 , general electronic , milwaukee , wi , usa ) . prostate volume was measured by using the prostate ellipsoid formula , multiplying the largest anteroposterior ( height , h ) , transverse ( width , w ) , and cephalocaudal ( length , l ) prostate diameters by 0.524 ( hxwxlxii/6 ) by using trus . bmi was calculated as the weight ( kg ) divided by the square of the height ( m ) , and waist - to - hip ratio ( whr ) was determined as the waist circumference divided by the hip circumference . waist circumference was measured by placing a tape measure snugly at the horizontal level between the subcostal margin and pelvic brim . exclusion criteria included presence of pyuria ( white blood cells>5 on urinalysis ) , the presence of neurogenic bladder dysfunction , confirmed prostate cancer , a history of recurrent urinary tract infections or bladder stones , or any other history of lower urinary tract disorder influencing urination . in addition , individuals who used medications affecting prostate growth , such as anti - androgens and 5--reductase inhibitors , or who had abnormal findings on the dre were excluded from the study . t - tests were conducted to compare the differences in men 's general health scores according to other parameters , such as psa , testosterone level , egfr , and total prostate volume ( tpv ) . chi - square or fisher exact test were conducted to compare the differences in mens ' general health scores according to mets , obesity , and central obesity . univariate and multivariate logistic regression analyses were performed for each group to determine the significance of age , psa , testosterone , egfr , and tpv as predictors of men 's health problems . the study protocol was approved by the institutional review board in national police hospital ( seoul , korea ; irb registration number-11100176 - 201412-hr-008 ) . between march and september 2013 , a total of 1910 healthy korean men aged 40 to 59 years who participated in a health examination were included . all men underwent detailed clinical evaluations by use of the ipss , nih - cpsi , adam , iief-5 , and pedt questionnaires . blood and urine samples were obtained for serum prostate - specific antigen ( psa ) and testosterone measurement between 0700 and 0900 . the estimated glomerular filtration rate ( egfr ) was calculated and metabolic syndrome ( mets ) was evaluated . the egfr was calculated by using the abbreviated four - variable modification of diet in renal disease equation : gfr=186.3(serum creatinine)-1.154(age)-0.203(0.742 if female)(1.210 if black ) mets was defined by using the criteria established by the national cholesterol education program - adult treatment panel iii published in 2005 . mets was diagnosed when at least three of the following criteria were present : ( 1 ) waist circumference greater than 90 cm or body mass index ( bmi ) higher than 25 kg / m , ( 2 ) systolic blood pressure 130 mmhg or greater or diastolic blood pressure 85 mmhg or greater or use of antihypertensive medication , ( 3 ) fasting blood sugar greater than 110 mg / dl or self - reported diabetes medication use , ( 4 ) triglyceride greater than 150 mg / dl , and ( 5 ) high - density lipoprotein cholesterol less than 45 mg / dl or use of lipid medication . thereafter , all of the participants underwent a digital rectal examination ( dre ) to screen for prostate enlargement or nodules suggesting prostate cancer . next , transrectal ultrasound ( trus ) was performed and ultrasonographic inspection of the prostate was performed in each subject by using a 3.5-mhz transducer ( voluson 730 , general electronic , milwaukee , wi , usa ) . prostate volume was measured by using the prostate ellipsoid formula , multiplying the largest anteroposterior ( height , h ) , transverse ( width , w ) , and cephalocaudal ( length , l ) prostate diameters by 0.524 ( hxwxlxii/6 ) by using trus . bmi was calculated as the weight ( kg ) divided by the square of the height ( m ) , and waist - to - hip ratio ( whr ) was determined as the waist circumference divided by the hip circumference . waist circumference was measured by placing a tape measure snugly at the horizontal level between the subcostal margin and pelvic brim . exclusion criteria included presence of pyuria ( white blood cells>5 on urinalysis ) , the presence of neurogenic bladder dysfunction , confirmed prostate cancer , a history of recurrent urinary tract infections or bladder stones , or any other history of lower urinary tract disorder influencing urination . in addition , individuals who used medications affecting prostate growth , such as anti - androgens and 5--reductase inhibitors , or who had abnormal findings on the dre were excluded from the study . t - tests were conducted to compare the differences in men 's general health scores according to other parameters , such as psa , testosterone level , egfr , and total prostate volume ( tpv ) . chi - square or fisher exact test were conducted to compare the differences in mens ' general health scores according to mets , obesity , and central obesity . univariate and multivariate logistic regression analyses were performed for each group to determine the significance of age , psa , testosterone , egfr , and tpv as predictors of men 's health problems . the study protocol was approved by the institutional review board in national police hospital ( seoul , korea ; irb registration number-11100176 - 201412-hr-008 ) . among 1,910 participants , 1,899 patients completed urological and psychiatric evaluations and did not meet the previous exclusion criteria . the median age of the patients was 53 years , and the median values of bmi and whr were 24.8 kg / m and 0.93 , respectively . bmi was categorized into two groups : nonobese ( < 24.8 kg / m ) and obese ( 24.8 kg / m ) because 24.8 kg / m was the median value in the healthy volunteers . we also divided the patients into two groups by their whr , either above or below 0.93 , the median value in the healthy volunteers . the data on the patients ' ages , serum psa levels , and testosterone levels and the results of the anthropometric measurements are summarized in table 1 . in addition , the median scores on the ipss , nih - cpsi , adam , iief-5 , and pedt are summarized in table 1 . we examined men 's general health by using several clinical parameters , including obesity - related parameters . to analyze differences in men 's general health according to various clinical parameters , we divided the five questionnaire groups into two subgroups each depending on the degree of symptom severity ( table 2 ) . in this study , moderate to severe luts was defined as an ipss score8 , and the group with moderate to severe luts had relatively greater tpv than did the group with no or mild luts ( p=0.001 ) . other clinical parameters were not significantly different between the two groups divided by severity of luts . moderate to severe nih - cpsi was defined as a score over 14 , and inversely , those men showed a lower prevalence of mets ( p=0.023 ) than did men in the group with no or mild cpsi . other clinical parameters , including obesity - related parameters , did not differ significantly between the two groups divided by severity of nih - cpsi . to evaluate the sex life of the patients , we divided the subjects by iief-5 score . moderate to severe ed was defined as a score less than 12 . in this study , the group with moderate to severe ed showed a relatively higher prevalence of mets ( p=0.012 ) and central obesity ( measured by whr0.93 ) ( p<0.001 ) . there were no statistically significant differences in other clinical parameters between the two groups divided according to the severity of their iief-5 scores . for the two remaining questionnaires , adam and pedt , there were no significant differences between subgroups . we evaluated the predictive value of several factors for moderate to severe luts by looking at ipss scores over 7 . multiple logistic regression analyses revealed that age and total tpv were independent predictors of moderate to severe luts in the multivariate analysis ( p=0.001 , odds ratio [ or ] , 1.034 ; 95% confidence interval [ ci ] , 1.014 - 1.056 ; p=0.010 , or , 1.019 ; 95% ci , 1.004 - 1.033 ; respectively ) ( table 3 ) we evaluated the predictive value of several factors for moderate to severe cp - like symptoms by nih - cpsi scores over 14 . as determined by logistic regression analysis , mets was the only significant negative predictive factor for moderate to severe cpsi scores ( p=0.022 ; or , 0.747 ; 95% ci , 0.581 - 0.959 ) ( table 4 ) . we evaluated the predictive value of several factors for moderate to severe aging male 's symptoms by adam scores over 36 . multiple logistic regression analyses revealed that age was the only significant independent predictor for moderate to severe adam score ( p=0.018 ; or , 1.024 ; 95% ci , 1.004 - 1.045 ) . the degree of ed was considered moderate to severe when the score on the iief-5 questionnaire was 11 or lower . the logistic regression analysis showed that age and mets were independent predictive factors for moderate to severe ed in the multivariate analysis ( p<0.001 , or , 1.121 ; 95% ci , 1.087 - 1.156 ; p=0.036 , or , 1.323 ; 95% ci , 1.018 - 1.720 ; respectively ) . whr had a statistically significant value for predicting moderate to severe ed in the univariate analysis ( p=0.016 ; or , 47.683 ; 95% ci , 2.080 - 1,093.027 ) ( table 6 ) . thus , higher age , existence of mets , and central obesity measured by whr had predictive ability for ed . among 1,910 participants , 1,899 patients completed urological and psychiatric evaluations and did not meet the previous exclusion criteria . the median age of the patients was 53 years , and the median values of bmi and whr were 24.8 kg / m and 0.93 , respectively . bmi was categorized into two groups : nonobese ( < 24.8 kg / m ) and obese ( 24.8 kg / m ) because 24.8 kg / m was the median value in the healthy volunteers . we also divided the patients into two groups by their whr , either above or below 0.93 , the median value in the healthy volunteers . the data on the patients ' ages , serum psa levels , and testosterone levels and the results of the anthropometric measurements are summarized in table 1 . in addition , the median scores on the ipss , nih - cpsi , adam , iief-5 , and pedt are summarized in table 1 . we examined men 's general health by using several clinical parameters , including obesity - related parameters . to analyze differences in men 's general health according to various clinical parameters , we divided the five questionnaire groups into two subgroups each depending on the degree of symptom severity ( table 2 ) . in this study , moderate to severe luts was defined as an ipss score8 , and the group with moderate to severe luts had relatively greater tpv than did the group with no or mild luts ( p=0.001 ) . other clinical parameters were not significantly different between the two groups divided by severity of luts . moderate to severe nih - cpsi was defined as a score over 14 , and inversely , those men showed a lower prevalence of mets ( p=0.023 ) than did men in the group with no or mild cpsi . other clinical parameters , including obesity - related parameters , did not differ significantly between the two groups divided by severity of nih - cpsi . to evaluate the sex life of the patients , we divided the subjects by iief-5 score . moderate to severe ed was defined as a score less than 12 . in this study , the group with moderate to severe ed showed a relatively higher prevalence of mets ( p=0.012 ) and central obesity ( measured by whr0.93 ) ( p<0.001 ) . there were no statistically significant differences in other clinical parameters between the two groups divided according to the severity of their iief-5 scores . for the two remaining questionnaires , adam and pedt , there were no significant differences between subgroups . we evaluated the predictive value of several factors for moderate to severe luts by looking at ipss scores over 7 . multiple logistic regression analyses revealed that age and total tpv were independent predictors of moderate to severe luts in the multivariate analysis ( p=0.001 , odds ratio [ or ] , 1.034 ; 95% confidence interval [ ci ] , 1.014 - 1.056 ; p=0.010 , or , 1.019 ; 95% ci , 1.004 - 1.033 ; respectively ) ( table 3 ) we evaluated the predictive value of several factors for moderate to severe cp - like symptoms by nih - cpsi scores over 14 . as determined by logistic regression analysis , mets was the only significant negative predictive factor for moderate to severe cpsi scores ( p=0.022 ; or , 0.747 ; 95% ci , 0.581 - 0.959 ) ( table 4 ) . we evaluated the predictive value of several factors for moderate to severe aging male 's symptoms by adam scores over 36 . multiple logistic regression analyses revealed that age was the only significant independent predictor for moderate to severe adam score ( p=0.018 ; or , 1.024 ; 95% ci , 1.004 - 1.045 ) . the degree of ed was considered moderate to severe when the score on the iief-5 questionnaire was 11 or lower . the logistic regression analysis showed that age and mets were independent predictive factors for moderate to severe ed in the multivariate analysis ( p<0.001 , or , 1.121 ; 95% ci , 1.087 - 1.156 ; p=0.036 , or , 1.323 ; 95% ci , 1.018 - 1.720 ; respectively ) . whr had a statistically significant value for predicting moderate to severe ed in the univariate analysis ( p=0.016 ; or , 47.683 ; 95% ci , 2.080 - 1,093.027 ) ( table 6 ) . thus , higher age , existence of mets , and central obesity measured by whr had predictive ability for ed . because qol has improved in recent years , more attention is being paid to diseases that influence qol rather than to only life - threatening diseases . luts , ed , and premature ejaculation are such diseases that affect qol in elderly men . to further our understanding about the seriousness of middle - aged men 's health , we assessed the severity of men 's urinary tract symptoms , sexual function , and premature ejaculation by using validated questionnaires . over the past decades , many different groups have investigated the influence of obesity on the development of bph and luts with conflicting results . most of these groups concluded that overall obesity , abdominal obesity , and whr can increase the risk of bph and luts , at least to some degree . in our study , to minimize the effect of comorbidity by senility , the age of patients was confined to 40 to 59 years , representing middle - aged men . a total of 1899 healthy korean men aged 40 to 59 years were included , and the age range was selected because it encompassed the aged most closely associated with prostatitis and ed . first , we showed that clinical parameters including obesity - related parameters did not differ significantly between the groups divided by ipss , nih - cpsi , iief-5 , adam , and pedt scores , except for tpv and mets . our results indicated that the group with moderate to severe luts had a relatively greater tpv . second , the group with moderate to severe nih - cpsi scores had a lower prevalence of mets . third , according to iief-5 , the group with moderate to severe ed showed a relatively higher prevalence of mets and central obesity as measured by whr . fifth , mets was the only significant negative predictive factor for moderate to severe cpsi scores . we could not find a definite reason for the negative relationship between mets and cp - like symptoms in our study . however , we suspect that effects of dietary and healthy behaviors could be important issues in this relationship . suggested that cp / chronic pelvic pain syndrome ( cpps ) is a multifactorial disease . cigarette smoking , a high - calorie diet with low fruit and vegetable consumption , constipation , slow digestion , a sexual relationship with more than one partner , and coitus interruptus were more likely in patients with cp / cpps than in controls . in addition , zhang et al .   reported that higher leisure - time physical activity was associated with a lower risk of cp / cpps . patients diagnosed with mets often give a lot of attention to their eating habits and lifestyle . further studies are needed to better characterize the etiopathogenesis in individuals to define the optimal approach to diagnosis and treatment . sixth , we revealed that age was the only significant independent predictor for moderate to severe adam scores . finally , we revealed that aging , the existence of mets , and central obesity measured by whr had predictive ability for ed . interestingly , we found no evidence that higher bmi in middle age is associated with an increased risk of luts , ed , or other related men 's health concerns . overall , there are clear advantages of using whr ; it is convenient and simple to measure and an easy metric in diagnosing not only the sequelae normally associated with mets , but also voiding dysfunction . whr may therefore be both useful and important as a measure of success for possible future treatment options for patients with ed . active reduction of waist circumference via treatment of mets in addition to treatment of pelvic inflammation and ischemia may lead to durable and material improvement in ed . other studies have also shown that weight loss significantly improves insulin sensitivity , erectile function , and testosterone levels in men . to our knowledge , this is first study simultaneously assessing several clinical parameters including obesity - related parameters and the five questionnaires for assessing middle - aged men 's health . we studied a large number of subjects in a population - based study , and there are few asian studies in which more than 1,500 subjects were analyzed . this is the first large - scale study of korean middle - aged men using the five validated questionnaires . the number of patients in this study was large enough to achieve a representation of middle - aged men . although several studies have shown an association of luts and obesity , there are few studies regarding the effects of the five validated questionnaires representing men 's urinary symptoms and sexual function according to several clinical parameters . our data showed median values and several functional status indexes of middle - aged korean men . although the five questionnaires that we used were validated , studies based on questionnaires have limitations in that they do not include basic disease development and limited information can be obtained , particularly regarding diagnostics . because we only used the five questionnaires to assess luts and sexual function , we lacked the detailed medical and social history of the patients . another limitation of this study was that the data were cross - sectional and did not provide information regarding the temporal cause - effect relationship between the clinical parameters and middle - aged men 's general health . the baseline demographics of the men enrolled in this study were not fully inspected or randomized ; thus , the baseline comorbidity of each patient may have affected the patients ' responses to the questionnaires . because this study consisted of data from a single institution , there may be a potential selection bias as well . in the future , local population - based studies and randomized controlled trials it is meaningful that this study showed a relationship of several clinical parameters with middle - aged men 's general health in a population - based study . our data showed that tpv is a significant predictor of luts , and our results indicated that age and tpv were associated with the severity of luts symptoms . it is suggested that patients with mets are not prone to cp - like symptoms . also , we showed that aging , the existence of mets , and central obesity measured by whr had predictive ability for ed . whr is a convenient and simple measurement , so it may therefore be useful and important as a measure of success for future treatment .