according to the international continence society ( ics ) , overactive bladder ( oab ) is a condition characterized by frequency ( > 8 micturitions per day ) and nocturia ( waking one or more times at night to void ) with or without urge incontinence ( involuntary emptying of the contents of the bladder ) .
many epidemiological and clinical studies have shown that oab affects the physical and mental health of patients and is an economic and social burden to patients .
epidemiological and clinical studies have surveyed the symptoms and causes and the prevalence of oab .
estimates of oab prevalence differ , but almost all studies have shown that its prevalence increases with age . there is also some evidence of an association with depression .
many previous studies on oab have been limited to the elderly or to subjects with incontinence [ 4 - 6 ] .
we conducted a cross - sectional study of subjects aged over 40 years in an urban and a rural region to measure the prevalence of oab in the community and assessed the risk factors for the condition .
the study participants were 1,226 subjects aged over 40 years in guri city and yangpyeong county , south korea , who were approached in october and november 2010 .
the response rate was 74.2% ( 940 responders out of 1,226 ) , and a few participants with incomplete questionnaire were excluded ( n=14 ) .
therefore , a total of 926 subjects were included in the final analysis ( fig .
the protocol of this study was developed by the department of preventive medicine , hanyang university college of medicine .
the survey was conducted with the overactive bladder symptom score ( oabss ) questionnaire ( table 1 ) .
oab was defined according to the ics as urgency with or without urge incontinence , and usually with frequency and nocturia . in this study ,
oab was defined as over 2 points for the urgency score and 3 points for the sum of total scores in the oabss questionnaire .
they included dwelling place ( rural or urban area ) , marital status , education , behavioral factors ( smoking , drinking , etc ) , and self - reported medical history , including hypertension , stroke , myocardial infarction , angina , hyperlipidemia , diabetes , osteoporosis , arthritis , tuberculosis , asthma , rhinitis , atopic dermatitis , cataract , hepatitis b , and depression .
the individuals surveyed were divided into three groups in relation to smoking : a never smoking group ( no history of smoking ) , an ex - smoking group , and a current smoking group . in the same way
, individuals were classified in three categories with regard to drinking : the never - drinkers ( no history of drinking ) , the ex - drinkers , and the current drinkers .
categorical variables were analyzed by using a logistic regression model and were adjusted for age by using a logistic regression model .
the characteristics of the subjects are shown in table 2 . of the 926 subjects , 403 subjects ( 43.52% ) were male and 81 were female ( 15.5% ) .
a total of 130 subjects ( 14.1% ) were diagnosed with oab , including 49 males ( 12.2% ) and 81 females ( 15.5% ) .
a total of 694 of the responders lived in the rural area ( yangpyeong county ) , and 79 of them were diagnosed with oab ; 332 responders lived in the urban area ( guri city ) , and 51 of them were diagnosed with oab ( p=0.20 ) .
the distribution of oab among individuals with various other characteristics is presented in table 2 . according to educational status ,
the prevalence of oab was below 10% in those with an educational status of high school graduate or above ; in those with less than a high school level of eduction , the prevalence of oab was over 90% .
there were 28 people with a history of stroke , and the prevalence of oab with a history of stroke was 9/28 ( 32.1% ) .
there were 83 patients with a history of osteoporosis , and the prevalence of oab with a history of osteoporosis was 23/83 ( 27.7% ) .
there were 27 patients with a history of asthma , and the prevalence of oab with a history of asthma was 9/27 ( 33.3% ) .
there were 100 subjects with cataract , of whom 32 ( 32.0% ) met the criteria for oab .
the prevalence of oab was not related to other risk factors except for those mentioned above .
we used age - adjusted p - values to assess the risk factors for oab .
educational status ( p<0.0487 ) , stroke ( p<0.0414 ) , osteoporosis ( p<0.0208 ) , asthma ( p<0.0091 ) , rhinitis ( p < 0.0150 ) , and cataract ( p<0.0008 ) were significantly associated with oab ( table 3 ) .
other factors ( dwelling place , marital status , smoking , drinking , hypertension , diabetes , hyperlipidemia , myocardial infarction , angina , tuberculosis , atopic dermatitis , hepatitis b , and depression ) were not significantly associated with oab .
the prevalence of oab reaches 16.6% , and increases to 22.1 to 41.9% in people over 70 years of age [ 7 - 10 ] . as part of the national overactive bladder evaluation program in the united states ,
a large - scale telephone survey was conducted of 5,204 respondents of both sexes aged 18 years .
the total prevalence of oab reached 857/5204 ( 16.5% ) and attained 25% or more in people aged over 65 .
the prevalence of oab with urge incontinence was 319/857 ( 6.1% ) and the prevalence of oab without urge incontinence was 538/857 ( 10.4% ) .
in addition , in japan , many epidemiologic surveys and clinical studies have shown that the prevalence reaches 12.4% ; in individuals aged 70 to 79 years , it reaches 22.6% , and in those over 80 it reaches 36.8% [ 11 - 13 ] .
the prevalence of oab was found to increase with age in countries including korea [ 14 - 16 ] . in our study , oab prevalence was a little higher than in the korean european prospective investigation into cancer and nutrition ( epic ) study .
however , the study populations differed slightly between the korean epic study and our study ; our study population consisted of community - based subjects .
in particular , the korean epic study showed that storage lower urinary tract symptoms ( luts ) were more prevalent than voiding or post - micturition luts . in our study also , storage luts were more prevalent than other voiding symptoms .
we obtained the same result for age dependence and also identified other risk factors , though age was the most important risk factor .
the differences in oab prevalence between countries may be related to cultural factors including race and cultural circumstances .
stewart et al .   showed that the prevalence of oab without urge incontinence increased more steeply with age in men than in women and was significantly different by sex . in men ,
oab without urge incontinence increased approximately three - fold , whereas oab without urge incontinence gradually increased in women less than 44 years of age and reached a plateau in women over the age of 44 years . in our study , the prevalence of oab by sex was not significantly different .
this was probably because of differences between the populations studied in the united states and those studied in korea .
studies of other risk factors in japanese persons over 70 found that depression ( multiple adjusted odds ratio=2.07 ) , a recent drinking history , and obesity ( body mass index ) were significantly linked to the prevalence of oab . in our study
these variables were not risk factors , probably because of differences between the populations studied in japan and in korea , especially in terms of age . in our study , the age - adjusted p - value for depression was 0.0671 .
other studies have examined the relationship between oab and lifestyle , especially smoking , alcohol use , and diet , and reported that controlling these factors improved or prevented oab . in the present study , however , residential area , marital status , smoking , alcohol consumption , hypertension , diabetes , hyperlipidemia , myocardial infarction , angina , tuberculosis , atopic dermatitis , and hepatitis b were found to be unrelated to the risk of oab .
this difference may be due to differences in diet and national make - up between the groups surveyed .
previous studies have , like ours , found a clear relationship between lower educational status and risk of oab .
there is also a close relationship between socioeconomic status and educational level and it is the former that probably relates most directly to the risk of oab .
persons with a higher educational level are more likely to seek better health behaviors and may have healthier lifestyles , whereas persons with a lower educational level may have a higher prevalence of smoking , poor diet , more labor , and exposure to toxins .
the prevalence of oab in the general population is sizeable ; considering the odd ratio , it could be over - estimated .
second , the oab group identified by the questionnaire did not receive any clinical follow - up . despite these limitations ,
however , our study has clarified the prevalence of oab in korea and has identified several associated risk factors .
this study aimed at surveying the prevalence of oab in the community and the multiple risk factors for oab . analyzing the risk factors for oab may help in the diagnosis of oab .
use of these risk factors may be helpful for creating new criteria for oab with multiple risk factors .
the prevalence of oab in the community in korea was 14.1% and the identified risk factors for oab were age , educational status , stroke , osteoporosis , asthma , rhinitis , and cataract .
knowledge of these risk factors should facilitate the diagnosis and also the treatment of oab .
 purposeto evaluate the risk factors for overactive bladder ( oab ) in a population aged 40 years and over in the community.materials and methodswe conducted a community - based survey of oab in a population aged 40 years and over in guri city and yangpyeong county , south korea , by use of the overactive bladder symptom score ( oabss ) questionnaire . 
 a total of 926 subjects were included in the final analysis . 
 the definition of oab was more than 2 points for the urgency score and 3 points for the sum of scores . 
 in addition , the subjects were asked about age , dwelling place , marital status , educational status , behavioral factors ( smoking , drinking , etc ) , and medical history . 
 categorical variables were analyzed by using the logistic regression model and were adjusted for age by using the logistic regression model.resultsoverall oab prevalence was 14.1% ( 130/926 ) , made up of 49/403 males ( 12.2% ) and 81/523 females ( 15.5% ) . 
 oab prevalence increased with age ( p<0.0001 ) . 
 risk factors for oab were educational status ( age - adjusted p=0.0487 ) , stroke ( p=0.0414 ) , osteoporosis ( p=0.0208 ) , asthma ( p=0.0091 ) , rhinitis ( p=0.0008 ) , and cataract . other factors ( dwelling place , marital status , smoking , drinking , hypertension , diabetes , hyperlipidemia , myocardial infarction , angina , tuberculosis , atopic dermatitis , hepatitis b , and depression ) were not associated with oab.conclusionsthe prevalence of oab in our study was about 14.1% and the risk factors for oab were educational status , stroke , osteoporosis , asthma , rhinitis , and cataract . 
 knowledge of these risk factors may help in the diagnosis and treatment of oab . 