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Abstract

Background:

Epidemiological studies on urinary incontinence that used a validated international standard questionnaire are limited in Japan, and few studies have examined the sociodemographic and behavioral correlates of urinary incontinence.

Objective:

The aim of this study was to estimate the prevalence of urinary incontinence according to the Japanese version of the International Consultation on Incontinence Questionnaire-Short Form, and its sociodemographic and behavioral correlates among Japanese women.

Design:

A web-based cross-sectional study.

Methods:

A randomly sampled cross-sectional Internet survey was conducted in Japan among 3030 women aged 20–64 years. The International Consultation on Incontinence Questionnaire-Short Form score, sociodemographic, body mass index, medical and childbirth history, practice of pelvic floor muscle training, and medical care use were obtained. Descriptive statistics, the chi-square test, and forced-entry logistic regression analysis were used in data analysis.

Results:

Participants’ average age was 43.4 years, and the response rate was 32.9%. The prevalence of urinary incontinence was 25.5%, and it increased with age. Stress urinary incontinence was the most common subtype (57.4%), followed by urge urinary incontinence (20.3%) and mixed urinary incontinence (16.7%). Less than 5% of those with urinary incontinence had experience with pelvic floor muscle training and medical care use. Middle-aged and older (p < 0.001), overweight and obesity (p < 0.001), vaginal delivery status (p < 0.001), low back pain (p = 0.008), and previous pelvic floor muscle training engagement (p < 0.001) were significantly associated with urinary incontinence.

Conclusion:

Increasing population awareness of urinary incontinence from an early age and developing effective interventions for the identified at-risk groups, such as the middle-aged and older, those with overweight and obesity, and those with previous pregnancies, are urgently needed.

Keywords

International Consultation on Incontinence Questionnaire-Short Form preventive behaviors urinary incontinence women younger and middle-aged

Introduction

Urinary incontinence (UI), defined as any involuntary leakage of urine,¹ is a common health problem worldwide in women. A review of population studies showed that the prevalence of UI ranged from approximately 5% to 70%, with most studies globally reporting a range of 25%–45%.² In Asia, a large-scale epidemiological study was conducted in China, where the prevalence among women has been reported as 38.0%.³ In the only large-scale epidemiological study based on residents aged 40 years and above in Japan, 44.0% of women aged 40 years and above were found to experience UI.⁴ A higher prevalence has been reported in women than in men (13.1% versus 5.4%).⁵ The prevalence of UI has been reported to increase with age.⁶ Thus, the overall prevalence of UI is expected to increase in the near future,⁷ especially in Japan, where life expectancy is long and the population is rapidly aging. UI has been revealed to be associated with reduced health-related quality of life (QOL), limited social activity, and high medical expenditures for individuals.⁸ In addition, the economic burden of UI care is substantial, with an estimated direct cost of US$19.5 billion in the United States alone,⁹ and the total cost in the United Kingdom was approximately £818 million.¹⁰ Therefore, it is a public health priority not only in Japan but also worldwide to prevent UI, especially in women.

To assess the trend of UI in the Japanese population and discuss the need for health actions and medical services, identifying the prevalence of UI is essential. However, the previously reported prevalence of UI among women was largely different depending on the studies by Milsom and Gyhagen,⁷ possibly due to variations in the definition used, heterogeneity of the study populations, and population sampling procedures. Definitions of UI influence estimates of UI prevalence among women; however, various definitions of UI have been used in previous studies. Many previous studies used their domestic definition of UI,^7,11 in which evaluations of urinary leakage differ on a daily, weekly, monthly, or annual basis.⁷ Such definitions tend not to be examined for their validity and reliability. An international standardized questionnaire, such as the International Prostate Symptom Score, International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF), and King’s Health Questionnaire, can provide precise estimates of UI and compare its prevalence between international countries. However, few studies have estimated the prevalence of UI using standardized questionnaires, especially in Japan.¹²

Furthermore, the precise estimates of UI prevalence can be obtained from the studies of representative populations.¹¹ Numerous previous studies reporting the prevalence of UI focused on at-risk subpopulations, such as older adults¹³ and parous women.^2,14 However, population-based studies conducted in Norway and China revealed that the prevalence of UI was 14.2% in those younger than 40 years of age and 28% in those in their 30s,^3,15 suggesting that UI may be a problem faced by women of all ages. Nevertheless, there is little epidemiological evidence regarding the prevalence of UI in Japanese women, including younger ones. Therefore, further research is needed to assess the prevalence of UI using standardized, reliable, and validated questionnaires, with a focus on avoiding selection bias and obtaining a high response rate.

In addition, it is essential to understand the sociodemographic and behavioral correlates of UI to identify the characteristics of at-risk populations and develop effective interventions. Previously, the delivery status, body mass index (BMI), and education level have been consistently reported as correlates of UI worldwide.^13,16 Also, studies from South Korea¹⁷ and the United States¹⁸ have, respectively, reported employment status and household income as other sociodemographic factors associated with UI. However, in Japan, these factors have not been sufficiently examined. Moreover, pelvic floor muscle training (PFMT), an effective preventive behavior for UI, is recommended. However, no previous studies have examined the implementation rate of PFMT or whether PFMT is associated with UI prevalence among the general adult population. To further discuss public health and preventive strategies for UI, it is necessary to examine the implementation rate and population association of PFMT on UI.

Thus, this study examined the prevalence of UI using a validated international standard questionnaire (the ICIQ-SF) and its sociodemographic and behavioral correlates among Japanese women.

Methods

This study followed the Strengthening the Reporting of Observational studies in Epidemiology (STROBE) Guidelines.

Study design and participants

This cross-sectional Internet-based study was conducted in Japanese women aged 20–64 years. Data were obtained from registered individuals of a Japanese Internet research service company (MyVoice Communication, Inc., Tokyo, Japan). Data were collected in March 2019. This company’s database contains sociodemographic information on 1 million individuals across Japan who voluntarily participated in this database. The inclusion criteria were Japanese women, 20–64 years of age, and registration with the relevant Internet research company. The exclusion criterion was non-response or incomplete response to the items determining the UI.

Sample size determination

Sample size was calculated based on the prevalence of storage symptoms reported in a study by Botlero and colleagues (36.1%),¹⁴ with a 5% estimated error (d = 0.05), a 95% confidence interval (95% CI; α = 0.05, z = 1.96), and a 10% exclusion rate. The formula was as follows

\begin{array}{l} N = z^{2} \times \frac{p \times (1 - p)}{{(p \times d)}^{2}} \times (1 + 0.1) \\ = {1.96}^{2} \times \frac{(0.361 \times (1 - 0.361))}{{(0.361 \times 0.05)}^{2}} \times 1.1 \\ = 2991 \frac{44157}{45125} \end{array}

The set sample size and attributes in this study were as follows: 3000 adults, 20–64 years of age, and equity stratified by age group (20s, 30s, 40s, 50s, and 60s).

Data collection process

Candidates were randomly selected from a nationwide pool of 1 million individuals registered in the database of a Japanese Internet research services company, in accordance with the predetermined sample size and specified attributes. In total, 9199 women were randomly selected according to the set sample size and attributes from the database, and were subsequently invited to participate in this study via email with a link to access an online questionnaire in March 2019. All participants voluntarily completed an online informed consent form before answering the online questionnaire, and each participant received a reward point valued at 70 yen as an incentive to participate in the surveys. Final study participants responded to this questionnaire were 3030 women (response rate = 32.9%).

Measures

Symptoms of UI

UI symptoms were evaluated using the Japanese version of the ICIQ-SF, which is a fully validated self-reported questionnaire.^19,20 The ICIQ-SF asks participants to report the frequency of UI, amount of leakage, overall impact of UI on QOL, and situation surrounding the leakage, which identifies the prevalence, subtype, severity, and severity of UI. The ICIQ-SF consists of four items including a self-diagnostic question regarding the subtypes of UI, which has been shown to be a good screening instrument when assessing the UI subtype.²¹ Total scores were calculated from three items except a self-diagnostic question of subtypes (total range: 0–21) and were classified into the following four severity categories in addition to no UI (0 point), slight (1–5 points), moderate (6–12 points), severe (13–18 points), and very severe (19–21 points).²¹ In the self-diagnostic question regarding the subtype of UI, respondents who selected either or both of the following symptoms: (1) leaks when you cough or sneeze or (2) leaks when you are physically active/exercising were classified as having stress urinary incontinence (SUI). Respondents who selected “leaks before you can get to the toilet” were classified as having urge urinary incontinence (UUI). Respondents with symptoms of both SUI and UUI were classified as having mixed urinary incontinence (MUI). All other responses were categorized as having other UI.

Sociodemographics

The following sociodemographic characteristics were self-reported by participants: age, sex, educational attainment (high school or less, 2 years of college, or 4 years of university or higher), employment status (full-time, part-time, or unemployed), and household income (<5,000,000, 5,000,000–7,000,000, 7,000,000–10,000,000, or ⩾ 10,000,000 yen).

Health-related and behavioral variables

A self-reported height and weight were used to estimate the BMI, which was classified as normal weight (< 25.0 kg/m²), overweight (25.0–29.0 kg/m²), or obese (⩾ 30.0 kg/m²). Data on the presence of gynecological diseases in women were obtained. Childbirth history, delivery, delivery method (vaginal or cesarean section), and parity were self-reported. The presence of back pain and constipation was also investigated. In addition, the status of PFMT engagement and medical care was assessed as health behaviors related to UI. Participants were asked to respond with the most suitable status as follows: currently, previously, or never.

Statistical analyses

After excluding those with missing data for the relevant variables (n = 521), 2509 women were included in the final analysis. The outcome variable was categorized as a binary variable (presence of UI = 1 and absence of UI = 0). Descriptive statistics (mean and standard deviation for continuous variables; frequency and percentage for categorical variables) were computed for sociodemographic, health-related, and behavioral variables stratified by the UI status (presence or absence of UI). The estimated prevalence of each UI subtype was reported as frequency and percentage. Chi-square and independent sample t-tests were used to compare differences in the sociodemographic, health-related, and behavioral variables between UI statuses. Forced-entry logistic regression analysis was used to evaluate the independent associations of these variables, excluding medical care use with UI, and the results were calculated for each variable as adjusted odds ratios with 95% CIs. All statistical analyses were performed using SPSS statistics version 27 (IBM Corp., Armonk, NY, USA), and the level of significance was set at p < 0.05.

Results

Basic characteristics of the study participants

Table 1 presents the basic characteristics of the study participants according to their UI status. Participants’ mean age was 43.4 ± 12.3 years (95% CI: 0.45–0.49). Of all participants, 43.0% (95% CI: 0.41–0.45) completed 4 years college or graduate school. Approximately two-fifths (39.0%, 95% CI: 0.37–0.41) of the population was employed full-time. The proportion of those who had a household income less than 5 million yen was 46.1% (95% CI: 0.44–0.48). Regarding health-related and behavioral variables, 85.7% (95% CI: 0.84–0.87) of participants were normal weight. Among those who had delivered a baby (48.9%), most had vaginal delivery (42.0%, 95% CI: 0.60–0.80). The prevalence of low back pain was 69.6% (95% CI: 0.68–0.71).

Table 1.

Sociodemographic health-related characteristics of the study participants (N = 2503).

Characteristic		Total sample2503	95% CI	UI present639 (25.5%)	UI absent1864 (74.5%)	95% CI^#	p^#
Age (years), M (SD)		43.38 (12.3)	0.45 to 0.49	47.00 (11.3)	42.13 (12.4)	−5.91 to −3.83	<0.001
Age group (years), n (%)	20–29	444 (17.7)	0.16 to 0.19	64 (10.0)	380 (20.4)	0.33 to 0.58	<0.001
	30–39	574 (22.9)	0.21 to 0.25	102 (16.0)	472 (25.3)	0.44 to 0.71
	40–49	589 (23.5)	0.22 to 0.25	169 (26.4)	420 (22.5)	1.01 to 1.52
	50–59	598 (23.9)	0.22 to 0.26	206 (32.2)	392 (21.0)	1.46 to 2.18
	60–65	298 (11.9)	0.11 to 0.13	98 (15.3)	200 (10.7)	1.16 to 1.96
Education level	High school or less	653 (26.1)	0.24 to 0.28	171 (26.8)	482 (25.9)	0.86 to 1.28	0.006
	2 years of college	773 (30.9)	0.29 to 0.33	225 (35.2)	548 (29.4)	1.08 to 1.58
	⩾4 years of university	1077 (43.0)	0.41 to 0.45	243 (38.0)	834 (44.7)	0.63 to 0.91
Employment, n (%)	Unemployed	897 (35.8)	0.34 to 0.38	245 (38.3)	652 (35.0)	0.96 to 1.39	0.013
	Part-time job	630 (25.2)	0.24 to 0.27	176 (27.5)	454 (24.4)	0.96 to 1.45
	Full-time job	976 (39.0)	0.37 to 0.41	218 (34.1)	758 (40.7)	0.63 to 0.91
Household income (yen), n (%)	<5,000,000	1153 (46.1)	0.44 to 0.48	266 (41.6)	887 (47.6)	0.66 to 0.94	0.061
	5,000,000–7,000,000	570 (22.8)	0.21 to 0.25	152 (23.8)	418 (22.4)	0.87 to 1.34
	7,000,000–10,000,000	486 (19.4)	0.18 to 0.21	136 (21.3)	350 (18.8)	0.94 to 1.46
	>10,000,000	294 (11.7)	0.11 to 0.13	85 (13.3)	209 (11.2)	0.93 to 1.59
BMI (kg/m²), M (SD)		21.42 (3.8)	0.92 to 0.94	22.63 (4.3)	21.01 (3.4)	−2.00 to −1.26	<0.001
BMI (kg/m²), n (%)	<25	2145 (85.7)	0.84 to 0.87	73 (11.4)	402 (21.6)	0.35 to 0.56	<0.001
	25–29	273 (10.9)	0.10 to 0.12	101 (15.8)	171 (9.2)	1.42 to 2.41
	⩾30	85 (3.4)	0.03 to 0.04	44 (6.9)	42 (2.3)	2.13 to 5.08
Delivery, n (%)	Nulliparity	1278 (51.1)	0.49 to 0.53	245 (38.3)	1033 (44.4)	0.42 to 0.60	<0.001
	Vaginal delivery	1051 (42.0)	0.60 to 0.80	360 (56.3)	691 (37.1)	1.83 to 2.63
	Cesarean section	174 (7.0)	0.40 to 0.44	34 (5.3)	140 (7.5)	0.47 to 1.02
Parity, n (%)	1	465 (18.6)	0.17 to 0.20	143 (22.4)	322 (17.3)	1.11 to 1.72	0.347
	2	580 (23.2)	0.22 to 0.25	185 (29.0)	395 (21.2)	1.24 to 1.86
	3 or more	180 (7.2)	0.06 to 0.08	66 (10.3)	114 (6.1)	1.29 to 2.43
Gynecological diseases, n (%)		304 (12.1)	0.87 to 0.89	100 (15.6)	204 (10.9)	1.17 to 1.96	0.002
Low back pain, n (%)		1742 (69.6)	0.68 to 0.71	480 (75.1)	1262 (67.7)	1.17 to 1.77	<0.001
Constipation, n (%)		492 (19.7)	0.18 to 0.21	124 (19.4)	368 (19.7)	0.78 to 1.23	0.853
PFMT engagement, n (%)	Never	2141 (85.5)	0.84 to 0.87	496 (77.6)	1645 (88.3)	0.37 to 0.58	<0.001
	Previously	214 (8.5)	0.08 to 0.10	100 (15.6)	114 (6.1)	2.14 to 3.79
	Currently	148 (5.9)	0.05 to 0.07	43 (6.7)	105 (5.6)	0.84 to 1.74
Medical care use, n (%)	Never	2396 (95.7)	0.95 to 0.97	594 (93.0)	1802 (96.7)	0.31 to 0.67	<0.001
	Previously	70 (2.8)	0.02 to 0.04	31 (4.9)	39 (2.1)	1.48 to 3.86
	Currently	37 (1.5)	0.01 to 0.02	14 (2.2)	23 (1.2)	0.92 to 3.51

CI: confidence interval; UI: urinary incontinence; BMI: body mass index; PFMT: pelvic floor muscle training; SD: standard deviation.

Test statistics estimated using the chi-square or t-test.

Characteristics of participants with UI

The mean age (p < 0.001) and BMI (p < 0.001) of participants with UI were significantly higher than those of participants without UI. Those with UI were significantly less likely to have a higher educational attainment (p = 0.006) and full-time employment (p = 0.013). However, those with UI were significantly more likely to have had vaginal delivery (p < 0.001), gynecological diseases (p = 0.002), and lower back pain (p < 0.001) than those without UI. Regarding behavioral variables related to UI, only 6.7% (95% CI: 0.84–1.74) and 2.2% (95% CI: 0.92–3.51) of the participants with UI reported to currently engage in PFMT and use medical care; the likelihoods of current and previous engagement in PFMT (p < 0.001) and medical care use (p < 0.001) were significantly higher in those with UI than in those without UI.

Prevalence of UI

The prevalence of UI was 25.5% (n = 639), with 14.4% of women in their 20s, 17.7% in their 30s, 28.7% in their 40s, 34.4% in their 50s, and 32.8% in their 60s. Furthermore, the severities of UI were slight in 53.5% of participants, moderate in 41.9%, severe in 4.2%, and very severe in 0.3%. The mean ICIQ-SF score was 6.33 ± 3.06. The estimated prevalence of UI subtypes according to age group is shown in Figure 1. The prevalence of UI increased with age in those up to their 50s and decreased in those in their 60s. The most frequent UI subtype was SUI (57.4%), followed by UUI (20.3%), MUI (16.7%), and other UI (5.5%). The prevalence of SUI was similar in all age groups, whereas those of UUI and MUI increased with age.

Figure 1.

Prevalence of urinary incontinence by age.

Correlates of UI

Table 2 shows the associations of sociodemographic, health-related, and behavioral factors with UI. Age, the BMI, delivery status, presence of low back pain, and PFMT engagement status were significantly associated with the presence of UI. More specifically, women aged 40 years or older (p < 0.001) and those with a BMI ⩾ 25 kg/m² (p < 0.001), vaginal delivery (p < 0.001), and low back pain (p = 0.008) were significantly more likely to have UI than their counterparts. However, no significant associations were observed between the education level (p = 0.288, 0.679), employment status (p = 0.751, 0.519), and gynecological diseases (p = 0.083). In addition, those with previous PFMT engagement had a significantly higher odds of UI than those without (p < 0.001). There was no significant association between PFMT engagement and UI (p = 0.105).

Table 2.

Associations of sociodemographic, health-related, and behavioral factors with UI.

	AOR	95% CI	p
Age group, years
20–29	1.00	Ref.
30–39	1.01	0.71–1.44	0.959
40–49	2.00	1.42–2.80	<0.001
50–59	2.39	1.70–3.35	<0.001
60–65	2.16	1.46–3.20	<0.001
BMI category (kg/m²)
<25	1.00	Ref.
25–29	1.93	1.46–2.55	<0.001
⩾30	4.20	2.64–6.69	<0.001
Education
High school	1.00	Ref.
2 years of college	1.14	0.89–1.47	0.288
⩾4 years of university	1.05	0.82–1.35	0.679
Employment
Unemployed	1.00	Ref.
Part-time job	1.04	0.82–1.32	0.751
Full-time job	1.08	0.85–1.37	0.519
Delivery
Nulliparous	1.00	Ref.
Cesarean section	0.72	0.47–1.10	0.131
Vaginal delivery	1.71	1.38–2.12	<0.001
Gynecological diseases
No	1.00	Ref.
Yes	1.27	0.97–1.67	0.083
Low back pain
No	1.00	Ref.
Yes	1.33	1.08–1.65	0.008
PFMT engagement, n (%)
Never	1.00	Ref.
Previously	2.65	1.95–3.59	<0.001
Currently	1.38	0.94–2.02	0.105

AOR: adjusted odds ratio; 95% CI: 95% confidential interval; BMI: body mass index; PFMT: pelvic floor muscle training.

Odds ratio were calculated after adjustment for all variables listed in the table.

Discussion

This may be the first study to examine the prevalence of UI using an internationally standardized questionnaire and the association of sociodemographic, health-related, and behavioral factors with UI among Japanese women with a wide age range. The results revealed that the total estimated prevalence of UI was 25.5%. SUI was the most common UI subtype. Although the prevalence of UI was higher with advanced age, approximately 15% of younger women had the symptoms of UI. This study also found that > 90% of women with UI had no experience with PFMT and medical care use. Finally, being middle-aged and older, overweight or obese, and having vaginal delivery, low back pain, and previous PFMT engagement were found to be sociodemographic, health-related, and behavioral correlates of UI. These findings imply that developing and disseminating effective public health or population-based strategies to prevent and improve UI symptoms are crucial for not only middle-aged and older women but also younger women because of the low prevalence of well-known and effective strategies for UI, such as PFMT engagement and medical use. The sociodemographic and health-related correlates identified herein can be useful for prioritizing them as further intervention targets and determining more tailored intervention content for the at-risk population.

In this study, one in four younger and middle-aged women experienced symptoms of UI. Based on this finding, it is estimated that approximately 8.6 million women in Japan have some symptoms of UI. Previously, a limited number of previous population-based studies examined the prevalence of UI using an internationally standardized questionnaire such as the ICIQ-SF and reported prevalences of 39.0%, 46.4%, 48.0%, and 30.0% in France, Denmark, Germany, and China, respectively.^2,12,22,23 The present findings were much lower than results of these previous studies. One possible reason for this difference could be the age of the participants. All previous studies, except that from France, included adult women aged 18 or 20–80 years, whereas the age range of participants in the current study ranged from 20 to 64 years. Ethnic differences might be another possible reason.²⁴ When comparing the same age intervals, such as 30s, 40s, and 50s, between the present and previous European studies, the UI prevalence reported in European countries was still approximately 20% higher than that found in this Japanese study. Similarly, a large epidemiological study in Japan revealed that the average prevalence of UI was also much lower (21.4%) in women aged 20–79 years.¹¹ Considering the results of the Chinese study (30.0%) too, European women might be more vulnerable to UI than Asian women, partly due to a higher BMI.²⁵ Thus, it is necessary to conduct surveys in each country and take measures tailored to the characteristics of each ethnic group.²⁴ Both previous and present findings in Japan were only from women who registered with the Internet research service. Therefore, sampling bias may have occurred. Further population-based studies using the ICIQ-SF by means other than the Internet are required in Japan.

Regarding the subtype of UI, SUI was the most common type of UI, which was consistent with findings of many previous studies conducted worldwide.^15,26 In addition, the prevalence of SUI in this study seemed to have a tendency to decrease after 40 years of age, which is somewhat similar to previous findings.²⁷ A review of population studies from numerous countries reported that UUI and MUI increased with age, whereas SUI tended to be more dominate among younger women than among older women.² This tendency could be because of the progression of pure SUI to MUI. Thus, it is important to take public health action for SUI before 40 years of age to prevent the transition to MUI because MUI is challenging to diagnose and treat, as urinary symptoms are variable and guidelines for treatment are unclear.²⁸

Previously, a few studies have identified factors associated with the presence of UI among Japanese women. After adjusting for other factors in the model, age ⩾ 40 years was deleteriously associated with UI. Similarly, previous studies have revealed that the prevalence of UI increases with age.^2,3,27 This can be a result of anatomical and physiological changes in the urogenital system.²⁹ Moreover, menopause and hormonal factors may affect the increased prevalence of SUI among women aged ⩾ 40 years.³⁰ Similar to several previous studies that reported one factor consistently associated with UI,²² BMI was strongly related to the presence of UI in this study. A high BMI causes an increase in intra-abdominal and pelvic pressure during daily activities, which in turn may stress the pelvic floor secondary to increased pressure.³¹ Recurrence of these conditions contributes to functional disorders of the pelvic floor and urinary tract, particularly UI. Regarding delivery, the present finding is also consistent with numerous studies reporting a negative influence of vaginal delivery on UI. However, no apparent association between cesarean section and UI in this study was contrary to the findings of a previous study examining SUI.³² This might be due to the difference in the type of UI focused on and the few reports of cesarean section (8.7%) in this study. Further studies are required to draw conclusions. Low back pain was also found to be associated with UI in this study, which is similar to the findings of Welk and Baverstock.³³ The mechanism for this relationship is still unclear. However, UI may have been caused by a decreased inner unit resulting from chronic back pain.

Herein, previous PFMT engagement was identified as a factor associated with UI, suggesting that PFMT provided in Japan may have some issues in terms of feasibility and accessibility. In fact, only 6.7% of women who responded to the questionnaire reported to currently engage in PFMT, even though PFMT was recommended for the prevention and treatment of SUI and MUI by the International Consultation on Incontinence. In addition, those with previous and current medical care accounted for only < 5% of the study population. As one of the possible reasons for such a low prevalence of engaging in preventive behaviors, including PFMT and medical care use, Abhyankar et al.³⁴ reported that many women with UI often delay seeking help for their symptoms because of lack of awareness, embarrassment, and stigma. Thus, they might prefer to buy incontinence aids instead of contacting health professionals first.³⁵ However, further investigation is needed to clarify this because of the lack of previous findings except the present study.

This study has some limitations. First, it was based on a self-report questionnaire, and no objective measures were taken. However, the ICIQ-SF is a reliable, well-validated tool that correlates well with objective measures. Second, this study used a cross-sectional design, which does not imply a causal relationship. Third, web-based surveys allow easier data collection compared with traditional surveys, but it is difficult to control for selection bias, given that not all women have the same level of comfort on the Internet. The generalizability of the results is limited by the selection bias caused by the low response rates. Finally, setting an age limit for the study participants might have resulted in an underestimation of the true prevalence of UI in Japan.

Nevertheless, this study highlights the importance of early detection of UI, considering that most women with UI continue to experience UI for > 10 years and few have complete remission of UI.³⁶ In Japan, there is a lack of epidemiological evidence concerning the prevalence of UI among the general population of Japanese women, including younger individuals, using standardized questionnaires. In addition, there are no previous reports examining the correlation between UI and sociodemographic characteristics, and the implementation rate of PFMT, a preventive measure for UI. This study used globally standardized questionnaires to unveil the prevalence of UI among Japanese women, excluding the older adult population. Furthermore, this is the first study in Japan to investigate the correlation between UI prevalence and sociodemographic characteristics and behavioral factors. The present findings can be useful in providing an updated view of UI among adults and may help in developing new strategies and interventions to promote public health and well-being in Japan.

Conclusion

In Japan, one-fourth of younger and middle-aged women have UI. Although preventive behaviors, including PFMT engagement and medical care use, are effective in preventing and improving symptoms, few participants have been previously or are currently engaged in them. Age after 40 years, overweight and obesity, vaginal delivery, and low back pain were revealed as independent sociodemographic, health-related, and behavioral correlates of UI. Based on the present findings, promoting public awareness of the onset of UI in early adulthood and developing tailored and feasible interventions for the identified at-risk group are urgently needed to prevent UI onset and progression.

Supplemental Material

sj-docx-1-whe-10.1177_17455057231207754 – Supplemental material for Prevalence and sociodemographic correlates of urinary incontinence in Japanese women: A web-based cross-sectional study

Supplemental material, sj-docx-1-whe-10.1177_17455057231207754 for Prevalence and sociodemographic correlates of urinary incontinence in Japanese women: A web-based cross-sectional study by Aki Onishi and Ai Shibata in Women’s Health

Footnotes

Acknowledgements

None.

Declarations

ORCID iD

Aki Onishi

Supplemental material

Supplemental material for this article is available online.

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