Association Between Metabolic Syndrome and Male Overactive Bladder in a Japanese Population Based on Three Different Sets of Criteria for Metabolic Syndrome and the Overactive Bladder Symptom Score

Prostatic Diseases and Male Voiding Dysfunction Association Between Metabolic Syndrome and Male Overactive Bladder in a Japanese Population Based on Three Different Sets of Criteria for Metabolic Syndrome and the Overactive Bladder Symptom Score Kenji Ohgaki, Kazutaka Horiuchi, and Yukihiro Kondo OBJECTIVE METHODS

RESULTS

CONCLUSION

To investigate whether metabolic syndrome is a risk factor for overactive bladder (OAB) defined by the Overactive Bladder Symptom Score (OABSS). A digital rectal examination of the prostate and an OABSS questionnaire were conducted in 1031 men who visited our hospital for metabolic screening from April 2009 to March 2010. The OABSS includes scores for daytime frequency, nighttime frequency, urgency, and urgency incontinence. Relationships of OAB (defined as OABSS ⱖ3 with an urgency score ⱖ2) with metabolic syndrome diagnosed by Japan Society for the Study of Obesity (JASSO), National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III), and International Diabetes Federation (IDF) criteria were examined. The severity of OAB symptoms was compared among younger, middle-aged, and elderly men (⬍50, 50-64, and ⱖ65 years old, respectively) with and without metabolic syndrome. Diagnoses of metabolic syndrome were made in 16.4%, 16.9%, and 12.0% of the men using JASSO, NCEP-ATP III, and IDF criteria, respectively. Regardless of the presence of metabolic syndrome, aging was significantly associated with increased rates of moderate or severe OABSS findings and OAB defined by the OABSS. In middle-aged men, metabolic syndrome had a significant negative association with OAB rate. In elderly men, metabolic syndrome had a significant negative association with the total OABSS. A relationship between age and OAB was observed, but metabolic syndrome did not show a clear association with OAB. Our results suggest that OAB is associated with aging regardless of the presence of metabolic syndrome. UROLOGY 79: 1372–1378, 2012. © 2012 Elsevier Inc.

M

etabolic syndrome refers to a cluster of cardiovascular disease risk factors with an underlying pathophysiology that may be related to insulin resistance, elevated blood pressure, and atherosclerosis.1 Thus metabolic syndrome is a combination of hyperglycemia, lipid abnormalities, and hypertension, with visceral fat obesity as a common factor. The risk of developing metabolic syndrome is decreased by reducing

Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department of Urology; and Department of Urologic Surgery, Graduate School of Medicine, Nippon Medical School, Musashi Kosugi Hospital, Kawasaki, Kanagawa, Japan Reprint requests: Kenji Ohgaki, M.D., Department of Urology, Nippon Medical School, Musashi Kosugi Hospital, 1-396 Kosugi-cho Nakahara-ku, Kawasaki, Kanagawa, 211-8533, Japan. E-mail: [email protected] Submitted: November 5, 2011, accepted (with revisions): March 5, 2012

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© 2012 Elsevier Inc. All Rights Reserved

visceral fat because the overlap of each disease increases the risk of cardiovascular or cerebrovascular disease.2 The 2005 Japan Society for the Study of Obesity (JASSO) criteria,2 the 2005 National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) criteria,3 and the 2005 International Diabetes Federation (IDF) criteria4 are all used for diagnosis of metabolic syndrome in Japan. However, it is unclear which of the JASSO, NCEP-ATP III, and IDF criteria and which cutoff point for waist circumference are better predictors of the development of cardiovascular disease in the general Japanese population. Age- and multivariate-adjusted incidence of cardiovascular disease, coronary heart disease, and stroke are all significantly higher in men with metabolic syndrome defined by the NCEP-ATP III and IDF criteria compared with men without metabolic syndrome5; however, these results are not obtained using the JASSO criteria. The prevalence 0090-4295/12/$36.00 http://dx.doi.org/10.1016/j.urology.2012.03.006

Table 1. Comparison among JASSO, NCEP-ATP III, and IDF criteria for male metabolic syndrome Definition of Metabolic Syndrome Components Waist circumference High blood pressure

Fasting plasma glucose Dyslipidemia

JASSO, (1) ⫹ Any 2 or More of (2)-(4) (1) ⱖ85 cm (2) ⱖ130/85 mm Hg and/ or antihypertensive medication (3) ⱖ110 mg/dL and/or antidiabetic medication (4) Triglyceride ⱖ150 mg/ dL and/or HDL cholesterol ⬍40 mg/dL antihypertriglyceridemic medication and/or antihypercholesterolemic medication

of metabolic syndrome in Japanese middle-aged (40-64 years) and elderly (65-79 years) men are 13.3% vs 18.9%, 19.0% vs 21.4%, and 14.0% vs 14.8% using the JASSO, NCEP-ATP III, and IDF criteria, respectively, with no significant difference between middle-aged and elderly men using each of these sets of criteria.6 Overactive bladder (OAB) is defined by the International Continence Society (ICS) as a syndrome with urgency, with or without urge incontinence, and usually with frequency and nocturia.7 OAB symptoms are commonly observed in men with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH).8 Epidemiologic studies have demonstrated that LUTS, including OAB, occurs commonly in both men and women and shows an age-related increase in both sexes.9 The prevalence of male OAB symptoms, which are defined as daily urinary frequency of ⱖ8 times and urgency once or more per week in Japan, among adults aged ⱖ40 years old is approximately 14%.10 The Overactive Bladder Symptom Score (OABSS) is a self-assessment questionnaire for investigation of OAB symptoms. The OABSS includes 4 questions on daytime frequency, nighttime frequency, urgency, and urgency incontinence.11 OAB is defined as a total OABSS score ⱖ3 with an urgency score ⱖ2.11 LUTS may be a risk factor for metabolic syndrome, and correlations of LUTS with other risk factors for metabolic syndrome have been examined.12 However, several studies have found no correlation between LUTS and metabolic syndrome.13,14 A clear association between OAB and metabolic syndrome has also not been shown. With this background, we investigated whether metabolic syndrome is a risk factor for OAB defined by the OABSS.

MATERIAL AND METHODS

NCEP-ATP III for Asians, 3 or More of (1)-(5) (1) ⱖ 90 cm (2) ⱖ 130/85 mm Hg and/or antihypertensive medication (3) ⱖ100 mg/dL and/or antidiabetic medication (4) Triglyceride ⱖ150 mg/dL antihypertriglyceridemic medication (5) HDL cholesterol ⬍40 mg/dL antihypercholesterolemic medication

IDF for Asians, (1) ⫹ Any 2 or More of (2)-(5) (1) ⱖ 90 cm (2) ⱖ 130/85 mm Hg and/ or antihypertensive medication (3) ⱖ100 mg/dL and/or antidiabetic medication (4) Triglyceride ⱖ150 mg/dL antihypertriglyceridemic medication (5) HDL cholesterol ⬍40 mg/dL antihypercholesterolemic medication

sure of OAB. The presence of metabolic syndrome was also evaluated. Age, height, weight, waist circumference, blood pressure, fasting blood glucose, blood chemistry (including measurement of high density lipoprotein [HDL]), and prostate-specific antigen (PSA) level were evaluated in the general check-up and a digital rectal examination (DRE) was performed.

Evaluation of OAB The men completed the OABSS questionnaire for evaluation of daytime frequency, nighttime frequency, urgency, and urgency incontinence. Scores on the questionnaire of ⱕ5 were defined as mild and those of ⱖ6 as moderate or severe.11 OAB is defined as OABSS ⱖ3 with an urgency score ⱖ2.11

Diagnosis of Metabolic Syndrome Metabolic syndrome was diagnosed based on the 2005 JASSO criteria, the 2005 NCEP-ATP III criteria, and the 2005 IDF criteria (Table 1). The JASSO criteria define metabolic syndrome as a waist circumference ⱖ85 cm for men plus either systolic blood pressure (SBP) ⱖ130 mm Hg or diastolic blood pressure (DBP) ⱖ85 mm Hg (or treatment of previously diagnosed hypertension), fasting plasma glucose (FPG) ⱖ110 mg/dL (or previously diagnosed type 2 diabetes), and triglyceride level ⱖ150 mg/dL or HDL cholesterol ⬍40 mg/dL (or treatment for a lipid abnormality).2 The NCEP-ATP III criteria define metabolic syndrome as the simultaneous occurrence of at least 3 of the following 5 risk factors: waist circumference ⱖ90 cm for men, SBP ⱖ130 mm Hg or DBP ⱖ85 mm Hg (or treatment of previously diagnosed hypertension), FPG ⱖ100 mg/dL (or previously diagnosed type 2 diabetes), triglyceride level ⱖ150 mg/dL, and HDL cholesterol ⬍40 mg/dL (or treatment for a lipid abnormality).3 The IDF criteria define metabolic syndrome as a waist circumference ⱖ90 cm for men plus either SBP ⱖ130 mm Hg or DBP ⱖ85 mm Hg (or treatment of previously diagnosed hypertension), FPG ⱖ100 mg/dL (or previously diagnosed type 2 diabetes), triglyceride level ⱖ150 mg/dL, and HDL cholesterol ⬍40 mg/dL (or treatment for a lipid abnormality).4

Health Survey The study included 1031 men who participated in a general health check-up from April 2009 to March 2010. All of the men completed the Japanese version of the OABSS as a meaUROLOGY 79 (6), 2012

Statistical Analysis The 1031 men were classified into age groups based on age at the check-up. Men aged ⬍50, 50-64, and ⱖ65 years were 1373

1374

.005 .004 .001 1.36 ⫾ 1.21 0.0 2.4 1.84 ⫾ 1.81 5.0 11.1 .016 NS .002 1.49 ⫾ 1.40 2.3 4.0 1.84 ⫾ 1.81 4.8 11.3 1.59 ⫾ 1.51 3.6 5.9 1.82 ⫾ 1.80 4.5 10.9

NS ⫽ not significant; MS ⫽ metabolic syndrome.

0.31 ⫾ 0.65 0.07 ⫾ 0.27 0.46 ⫾ 0.86 0.09 ⫾ 0.39

NS NS NS

.012 NS 0.26 ⫾ 0.49 0.04 ⫾ 0.20 .040 NS

0.46 ⫾ 0.87 0.09 ⫾ 0.39

0.29 ⫾ 0.59 0.06 ⫾ 0.26

.014 NS

0.46 ⫾ 0.86 0.09 ⫾ 0.39

NS 0.73 ⫾ 0.69 0.81 ⫾ 0.82 NS 0.75 ⫾ 0.75 0.81 ⫾ 0.81 0.82 ⫾ 0.79 0.79 ⫾ 0.80

NS

.003 0.39 ⫾ 0.48 0.48 ⫾ 0.52 .023 0.39 ⫾ 0.49 0.48 ⫾ 0.52 0.39 ⫾ 0.49 0.48 ⫾ 0.52

.038

P Value NS NS NS 124 56.39 ⫾ 7.98 1.24 ⫾ 1.21 4.8 857 56.58 ⫾ 9.38 1.29 ⫾ 1.26 8.2

174 56.61 ⫾ 8.10 1.24 ⫾ 1.14 5.7

P Value NS NS NS

907 56.61 ⫾ 9.33 1.29 ⫾ 1.24 8.2

MS IDF Non-MS NCEP-ATP III MS Non-MS

P Value NS NS NS 169 57.60 ⫾ 7.66 1.24 ⫾ 1.17 6.5 862 56.38 ⫾ 9.43 1.29 ⫾ 1.25 8.0

Number Age (y) PSA (ng/mL) Enlarged prostate (%) OABSS Daytime frequency score Nighttime frequency score Urgency score Urgency incontinence score Total OABSS OABSS severity(%) OAB(%)

Severity of OAB The relationship of OAB-related factors with age is shown in Table 3. PSA level and a prostate larger than the normal size were more common in elderly men. The rates of moderate or severe total OABSS scores and OAB defined by the OABSS were also significantly higher in elderly men. Other factors had odds ratios from 1.0403.195 compared with the middle-aged and younger groups and elderly and middle-aged groups. Relationships between OAB-related factors and metabolic syndrome in each age group are shown in Table 4. There were no significant differences in OAB-related factors in younger patients with and without metabolic syndrome based on each of the 3 sets of criteria. The urgency subscore and rate of OAB had negative associations with metabolic syndrome based on the NCEP-ATP III criteria in middle-aged men. The daytime frequency subscore, rate of moderate or severe OABSS, and OAB were negatively

JASSO MS

Background of Subjects Of the 1031 men in the study, a diagnosis of metabolic syndrome was made in 169 (16.4%) based on the JASSO criteria, with rates of 12.4%, 17.6%, and 16.0% in the younger, middle-aged, and elderly men, respectively; in 174 (16.9%) based on the NCEP-ATP III criteria, with rates of 16.1%, 17.6%, and 14.7% in the respective age groups; and in 124 (12.0%) based on the IDF criteria, with rates of 11.4%, 13.2%, and 7.7%, respectively. There were no significant differences in the rates among the age groups based on any of the definitions of metabolic syndrome. Relationships of various factors with the presence of metabolic syndrome based on each set of criteria are shown in Table 2. There was no significant difference in age, DRE findings, or PSA level between patients with and without metabolic syndrome. The daytime frequency and urgency subscores were significantly higher in men without metabolic syndrome based on all criteria. Total OABSS scores were higher and OAB defined by the OABSS was significantly more common in men without metabolic syndrome based on the NCEP-ATP III and IDF criteria.

Non-MS

RESULTS

Table 2. Relationships between variables, including OABSS scores and the presence or absence of metabolic syndrome based on 3 sets of criteria

classified as younger, middle-aged, and elderly, respectively. The relationship of the presence of metabolic syndrome with each OABSS subscore or age group was investigated. The OABSS severity and OAB defined by the OABSS were also examined in subjects with and without metabolic syndrome and in different age groups. Discrete variables are shown as counts or frequencies, and differences were evaluated by chi-square test, Fisher exact test, or logistic regression analysis. Data with a skewed distribution (age, PSA level, and OABSS total scores and subscores) are shown as the median and interquartile range, and differences were analyzed by Student t-test and Mann– Whitney U test. SPSS version 4.0 was used for all analyses (SPSS, Inc., Chicago, IL) All statistical tests were 2-tailed with P ⬍.05 considered significant.

UROLOGY 79 (6), 2012

Table 3. Relationships between OAB-related factors and age

PSA (ng/mL) Enlarged prostate (%) OABSS severity (%) OAB (%)

PSA (ng/mL) Enlarged prostate (%) OABSS severity (%) OAB (%)

Younger Men

Middle-Aged Men

P Value

Odds Ratio

0.80 ⫾ 0.42 1.6 0.0 4.1

1.23 ⫾ 1.07 6.9 3.8 9.8

⬍.001 .003 .003 .013

4.688 (1.443-15.230) 1.040 (1.024-1.055) 2.519 (1.188-5.341)

Middle-Aged Men

Elderly Men

P Value

Odds Ratio

1.23 ⫾ 1.07 6.9 3.8 9.8

2.11 ⫾ 1.97 19.2 12.2 18.6

⬍.001 ⬍.001 ⬍.001 .003

2.791 (1.827-4.263) 3.195 (1.815-5.623) 1.892 (1.269-2.821)

Younger men ⫽ ⬍50 years old; middle-aged men ⫽ 50-64 years old; elderly men ⫽ ⱖ65 years old; NS ⫽ not significant.

associated with metabolic syndrome based on the IDF criteria in middle-aged men. The total OABSS score had a negative association with metabolic syndrome based on all criteria in elderly men. The nighttime frequency subscore was negatively associated with metabolic syndrome based on the IDF criteria in elderly men.

COMMENT OAB and BPH have been studied epidemiologically as causes of LUTS. OAB symptoms were found in 15.6% of male subjects ⬎40 years old in the European general population and were shown to increase with advancing age.15 A study in the United States reported a prevalence of OAB in male subjects ⬎18 years of 16.0% and also found an increase with age.16 Similarly, an epidemiologic study based on International Prostate Symptom Score (IPSS) scores in Western subjects found prevalences of moderate or severe symptoms of about 10% for men in their 40s and around 40% for men aged ⬎70 years.17,18 Surveys in several populations have also been conducted to identify risk factors for male LUTS. These studies have suggested relationships among LUTS, metabolic syndrome, and lifestyle-related diseases caused by lack of exercise, drinking, smoking, obesity, hypertension, hyperlipidemia, and cardiovascular disease.19 Basic research has suggested an association between OAB and metabolic syndrome, but clinical studies are scarce. Rahman et al found that rats fed a high-fat diet, leading to hyperlipidemia, had enlarged prostates and bladder overactivity.20 Persson et al showed that spontaneously hypertensive rats developed autonomic hyperactivity and prostatic hyperplasia, with subsequent detrusor overactivity and increased urinary frequency.17 Azadzoi et al found that arterial insufficiency in rabbits resulted in bladder overactivity, fibrosis, neuropathy, and decreased bladder compliance.18 We investigated whether metabolic syndrome is a risk factor for OAB using the OABSS. Several questionnaires are used for assessment of OAB. The Overactive Bladder Questionnaire (OAB-q) and the Patient Perception of Bladder Condition (PPBC) are useful for measuring OAB-related symptoms and health-related quality of life; therefore, these tools are more effective for evaluating UROLOGY 79 (6), 2012

treatment outcomes rather than for assessment of OAB symptoms themselves.21,22 The OAB-q is a 33-item, condition-specific measure designed to assess the impact of OAB symptoms on health-related quality of life (HRQL). The OAB-q consists of a Symptom Bother scale and four HRQL subscales (Coping, Concern, Sleep, and Social Interaction). All scale scores are transformed to a 0- to 100point scale, with higher Symptom Bother scores indicating greater symptom severity and lower HRQL subscale scores indicating greater impact.21 The PPBC is a single item that assesses the patients’ subjective impression of their current urinary problems. Patients are asked to rate their perceived bladder condition on a 6-point scale ranging from 1 (no problems at all) to 6 (many severe problems). To assess the change in the PPBC from baseline to the end of the study, the baseline value was subtracted from the value at the end of the study. The score changes typically ranged from ⫺2 to 2, with a negative value indicating improvement.22 In contrast, the OABSS is an assessment tool designed to quantify OAB symptoms in a single score. The OABSS, which has been validated in a cohort of Japanese patients, combines the response scores of 4 questions on individual symptoms. The recommended diagnostic criteria for OAB are “an urgency score for Question 3 of 2 or more, and a total OABSS of 3 or more.” The distribution of scores on the OABSS showed a clear separation between patients with OAB and asymptomatic controls. The OABSS is useful when evaluating symptoms because the score is obtained as the simple sum of 4 scores for daytime voiding, nighttime voiding, urgency, and urgency incontinence.11 In a previous study, we failed to find a positive association between metabolic syndrome and LUTS using the IPSS.14 No significant difference in age, digital rectal examination findings, or PSA level was found between men with and men without metabolic syndrome. In those without metabolic syndrome, a moderate or severe urgency score was significantly more common using the JASSO criteria; moderate or severe total IPSS and voiding subscores were significantly more common using the NCEP-ATP III criteria, and moderate or severe frequency and nocturia scores and total IPSS were significantly more common using the IDF criteria.14 These results suggest that waist circumference does not always 1375

1376 Table 4. Relationships between OAB-related factors and metabolic syndrome in each age group JASSO Younger Men Age (y) PSA (ng/mL) Enlarged prostate (%) OABSS Daytime frequency score Nighttime frequency score Urgency score Urgency incontinence score Total OABSS OABSS severity (%) OAB (%) Middle-Aged Men Age (y) PSA (ng/mL) Enlarged prostate (%) OABSS Daytime frequency score Nighttime frequency score Urgency score Urgency incontinence score Total OABSS OABSS severity(%) OAB(%) Elderly Men

UROLOGY 79 (6), 2012

Age (y) PSA (ng/mL) Enlarged prostate (%) OABSS Daytime frequency score Nighttime frequency score Urgency score Urgency incontinence score Total OABSS OABSS severity(%) OAB(%)

Non-MS n ⫽ 169

MS n ⫽ 24

41.61 ⫾ 4.78 0.79 ⫾ 0.43 1.2 0.38 ⫾ 0.51 0.30 ⫾ 0.58 0.17 ⫾ 0.51 0.00 ⫾ 0.00 0.86 ⫾ 1.10 0.0 4.1

NCEP-ATP III P Value

Non-MS n ⫽ 162

MS n ⫽ 31

44.75 ⫾ 3.91 0.83 ⫾ 0.36 4.2

.002 NS NS

41.65 ⫾ 4.80 0.81 ⫾ 0.44 1.9

0.21 ⫾ 0.41 0.42 ⫾ 0.58 0.13 ⫾ 0.45 0.00 ⫾ 0.00 0.75 ⫾ 0.99 0.0 4.2

NS NS NS NS NS NS NS

0.38 ⫾ 0.51 0.30 ⫾ 0.58 0.17 ⫾ 0.52 0.00 ⫾ 0.00 0.85 ⫾ 1.12 0.0 4.3

IDF P Value

Non-MS n ⫽ 171

MS n ⫽ 22

P Value

43.84 ⫾ 4.31 0.74 ⫾ 0.32 0.0

.019 NS NS

41.72 ⫾ 4.80 0.80 ⫾ 0.43 1.8

44.18 ⫾ 4.15 0.77 ⫾ 0.33 0.0

.023 NS NS

0.29 ⫾ 0.46 0.39 ⫾ 0.56 0.13 ⫾ 0.43 0.00 ⫾ 0.00 0.81 ⫾ 0.95 0.0 3.2

NS NS NS NS NS NS NS

0.37 ⫾ 0.51 0.30 ⫾ 0.57 0.17 ⫾ 0.51 0.00 ⫾ 0.00 0.84 ⫾ 1.10 0.0 4.1

0.32 ⫾ 0.48 0.45 ⫾ 0.60 0.14 ⫾ 0.47 0.00 ⫾ 0.00 0.91 ⫾ 1.02 0.0 4.5

NS NS NS NS NS NS NS

n ⫽ 562

n ⫽ 120

P Value

n ⫽ 562

n ⫽ 120

P Value

n ⫽ 592

n ⫽ 90

P Value

57.63 ⫾ 3.71 1.23 ⫾ 1.07 7.5

57.79 ⫾ 3.97 1.21 ⫾ 1.10 4.2

NS NS NS

57.68 ⫾ 3.70 1.22 ⫾ 1.07 18.0

57.58 ⫾ 3.99 1.25 ⫾ 1.08 12.8

NS NS NS

57.68 ⫾ 3.70 1.22 ⫾ 1.06 13.4

57.50 ⫾ 4.11 1.28 ⫾ 1.18 10.6

NS NS NS

0.48 ⫾ 0.51 0.78 ⫾ 0.73 0.46 ⫾ 0.87 0.07 ⫾ 0.36 1.80 ⫾ 1.68 3.9 10.7

0.43 ⫾ 0.50 0.81 ⫾ 0.76 0.33 ⫾ 0.65 0.08 ⫾ 0.26 1.63 ⫾ 1.49 3.3 5.8

NS NS NS NS NS NS NS

0.48 ⫾ 0.51 0.79 ⫾ 0.73 0.47 ⫾ 0.88 0.08 ⫾ 0.36 1.82 ⫾ 1.70 4.3 11.2

0.41 ⫾ 0.49 0.77 ⫾ 0.74 0.30 ⫾ 0.53 0.07 ⫾ 0.25 1.54 ⫾ 1.35 1.7 3.3

NS NS .045 NS NS NS .006

0.49 ⫾ 0.51 0.79 ⫾ 0.74 0.46 ⫾ 0.87 0.08 ⫾ 0.36 1.82 ⫾ 1.69 4.4 11.0

0.34 ⫾ 0.48 0.78 ⫾ 0.68 0.28 ⫾ 0.50 0.06 ⫾ 0.23 1.46 ⫾ 1.25 0.0 2.2

.014 NS NS NS NS .037 .007

n ⫽ 25

P Value

n ⫽ 133

n ⫽ 23

P Value

n ⫽ 144

n ⫽ 12

P Value

NS NS NS

70.11 ⫾ 4.60 2.17 ⫾ 2.01 19.5

68.74 ⫾ 3.91 1.85 ⫾ 1.71 17.4

NS NS NS

69.86 ⫾ 4.54 2.14 ⫾ 1.97 20.1

70.42 ⫾ 4.48 1.80 ⫾ 2.00 8.3

NS NS NS

0.62 ⫾ 0.52 1.48 ⫾ 0.89 0.79 ⫾ 1.03 0.24 ⫾ 0.62 3.13 ⫾ 2.17 12.8 20.3

0.39 ⫾ 0.50 1.17 ⫾ 0.83 0.48 ⫾ 0.79 0.09 ⫾ 0.42 2.13 ⫾ 1.77 8.7 8.7

0.60 ⫾ 0.52 1.49 ⫾ 0.88 0.78 ⫾ 1.03 0.24 ⫾ 0.61 3.10 ⫾ 2.16 13.2 20.1

0.33 ⫾ 0.49 0.83 ⫾ 0.83 0.33 ⫾ 0.49 0.00 ⫾ 0.00 1.50 ⫾ 1.17 0.0 0.0

n ⫽ 131 70.07 ⫾ 4.60 2.18 ⫾ 2.01 19.1

69.04 ⫾ 4.07 1.78 ⫾ 1.74 20.0

0.62 ⫾ 0.52 1.47 ⫾ 0.89 0.80 ⫾ 1.03 0.24 ⫾ 0.62 3.13 ⫾ 2.19 13.0 20.6

0.40 ⫾ 0.50 1.28 ⫾ 0.89 0.44 ⫾ 0.77 0.08 ⫾ 0.40 2.20 ⫾ 171 8.0 8.0

NS ⫽ not significant; MS ⫽ metabolic syndrome.

NS NS NS NS .046 NS NS

NS NS NS NS .038 NS NS

NS .014 NS NS .012 NS NS

increase with age because the volumes of abdominal subcutaneous fat and abdominal muscle decrease more quickly than accumulation of visceral fat. Japanese men are less likely to progress to BPH owing to differences in the Asian diet, lifestyle, and environment compared with the Western population.23 Similarly, in the current study, we did not find a clear association between metabolic syndrome and OAB using the OABSS. The reasons for the absence of this positive association may also lie in the Asian-specific diet and lifestyle, which cause Asians to have less severe obesity.24 Okumura et al found that subjects with moderate or severe OAB comprised 5% of those with a mild IPSS grade, 25-33% with a moderate IPSS grade, and 50-67% with a severe IPSS grade, indicating that the proportion of moderate or severe OAB cases increased with an increased IPSS grade.25 Jin et al suggested that prostate growth might accelerate after exposure to a Western diet, lifestyle, and environment because Chinese men living in China were found to have smaller prostate volumes compared with age-matched native-born Chinese men who had immigrated to Australia.23 Link et al demonstrated a dose-response relationship between adiposity and OAB for a body mass index (BMI) ⱖ27.5 kg/m2 and suggested that men with a greater pelvic floor, with 0.95 for the waist-to-hip circumference ratio, might be less susceptible to abdominal and intravesical pressure, thus avoiding symptoms caused by increased weight until reaching significant obesity.26 In all subjects, a higher BMI tended to decrease the rate of OAB symptoms, 3.7%, 11.0%, 8.7%, and 3.3% in underweight (BMI ⬍18.5 kg/m2), normal range (18.5 ⱕBMI ⬍25.0 kg/m2), overweight (25.0 ⱕBMI ⬍30.0 kg/m2), and obese (30.0 kg/m2 ⱕ BMI), respectively, because the prevalence of metabolic syndrome increased in middle-aged men compared with that in older men in this study. Metabolic syndrome is a worldwide phenomenon, with reports of prevalences of 25-30% in different European populations,27 24.0% in male subjects ⬎20 years old in the United States,28 and 12-24% in different Asian populations.27 An increased prevalence of metabolic syndrome with age may cause an association between metabolic syndrome and OAB. Therefore, it is of note that Ford et al found that the prevalence of metabolic syndrome increased with age28 and that Kuzuya et al showed that the prevalence of metabolic syndrome based on JASSO criteria was higher in males aged 40-59 years old.29 In a cross-sectional survey in China, Gu et al found that the prevalence of metabolic syndrome increased among men until 65 years old and then decreased slightly in older men.30 These findings suggest a similarity of age-specific changes in the prevalence rates of metabolic syndrome in Japanese and Chinese ethnic groups, although with some difference in the age of peak prevalence in males.29 However, an association between metabolic syndrome and OAB in men has not been reported and our results did not show a positive association beUROLOGY 79 (6), 2012

tween metabolic syndrome and OAB. This may be because we evaluated OAB symptoms using the OABSS only and we did not exclude OAB symptoms caused by bladder cancer, bladder calculus, interstitial cystitis, prostate cancer, bacterial cystitis, prostatitis, urethritis, and urinary retention. The prevalence of OAB was dependent on age, but the prevalence of metabolic syndrome was independent of age in our study. Again, this may be caused by Asian diet, lifestyle, and environment. An association of metabolic syndrome and OAB might not have been found because of the small increase in metabolic syndrome with age.

CONCLUSIONS Our results show that elderly Japanese men have an increased frequency of OAB but do not have a higher frequency of metabolic syndrome. Various criteria are used to define metabolic syndrome, and the prevalences of OAB and metabolic syndrome differ between Japanese and Western populations. However, regardless of these variables, we conclude that Japanese men with metabolic syndrome are not at an increased risk for OAB. References 1. Reaven GM. Banting lecture 1988. Role of insulin resistance in human disease. Diabetes. 1988;37:1595-1607. 2. Committee on Criteria for Metabolic Syndrome. Definition and criteria for metabolic syndrome. J Jpn Soc Intern Med. 2005;94:794809. 3. Grundy SM, Cleeman JI, Daniels SR, et al; American Heart Association; National Heart, Lung, and Blood Institute. Diagnosis and management of the metabolic syndrome: an American Heart Association/National Heart, Lung, and Blood Institute scientific statement. Circulation. 2005;112:2735-2752. 4. Alberti KG, Zimmet P, Shaw J. Metabolic syndrome—a new worldwide definition. A consensus statement from the international Diabetes Federation. Diabet Med. 2006;23:469-480. 5. Doi Y, Ninomiya T, Hata J, et al. Proposed criteria for metabolic syndrome in Japanese based on prospective evidence: the Hisayama study. Stroke. 2009;40:1187-1194. 6. Arai H, Yamamoto A, Matsuzawa Y, et al. Prevalence of the metabolic syndrome in elderly and middle-aged Japanese. J Clin Gerontol Geriatr. 2010;1:42-47. 7. Abrams P, Cardozo L, Fall M, et al; Standardisation Sub-committee of the International Continence Society. The standardisation of terminology of lower urinary tract function: report from the Standardisation Sub-Committee of the International Continence Society. Neurourol Urodyn. 2002;21:167-178. 8. Lee JY, Kim HW, Lee SJ, et al. Comparison of doxazosin with or without tolterodine in men with symptomatic bladder outlet obstruction and an overactive bladder. BJU Int. 2004;94:817820. 9. Irwin DE, Milsom I, Hunskaar S, et al. Population-based survey of urinary incontinence, overactive bladder, and other lower urinary tract symptoms in five countries: results of the EPIC study. Eur Urol. 2006;50:1306-1314. 10. Homma Y, Yamaguchi O, Hayashi K, et al. An epidemiological survey of overactive bladder symptoms in Japan. BJU Int. 2005;96: 1314-1318. 11. Homma Y, Yoshida M, Seki N, et al. Symptom assessment tool for overactive bladder syndrome— overactive bladder symptom score. Urology. 2006;68:318-323.

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