Table 3. Overview of published population-based studies assessing the prevalence of overactive bladder (OAB^*) among both sexes (MEDLINE and PubMed search to December 2006) with present study (in chronological order).

	Origin of the study sample
	European [3]	USA [4]	Canada [9]	Japan [6]	Porto Alegre [7]	Matsu [15]	International [16]	Finland
Design	Telephone interview (85%)†	Telephone interview	Telephone interview	Mailed questionnaire	Mailed (?) questionnaire	Questionnaire administered by nurse	Telephone interview	Mailed questionnaire
Respondents	16,776	5,204	3,249	4,570	913	1,921	19,165	3,727
Response rate (%)	Not reported	44.5/57.1‡	43.4	45.3	Not reported	67.0	33.0	62.4
Age range (years)	40–75+	18–75+	35–75+	40–100	15–55	30–79	18–70+	18–79
Representative age-distribution of adults §	No	Yes	No	No	No	No	Yes	Yes
Current definition of OAB	No	No	No	No	Yes	No	Yes	Yes
Time period	Not defined	Last 4 weeks	Past month	Past month	Not defined	Past 4 weeks	Not defined	Last 2 weeks
Exclusion criteria - UTI * /other	Yes/No	Yes/Yes	No/No	No/No	Yes/Yes	No/Yes	No/No	Yes/Yes
Non-response analysis for prevalence estimate	No	No	No	No	No	No	No	Yes
Prevalence of OAB (%)	17	16	18	12	19	17	12	8

^*OAB, overactive bladder; UTI, urinary tract infection

^†In the European study, in five out of six countries, telephone interview was used (excluding Spain where direct interviews were conducted due to lower proportion of households having telephone)

^‡Out of 11,740 participants (of 17,231 households contacted), 5,539 were considered ineligible. To calculate response rate, the number of respondents was divided by eligible participants (the former response rate). If same proportion of non-participants, as there were ineligible among participants (47%), were also considered ineligible, response rate was greater (the latter response rate).

^§Study sample was close to representative of the general population regarding age, and/or age-standardization was used.