The International Continence Society defines urinary incontinence (UI) as "the complaint of any involuntary leakage of urine" [1]. UI is an important health problem resulting in psychological, social, and hygienic impairment, thus affecting the lives of the patients as well as their family [2]. However, there are no studies on the overall prevalence, risk factors, quality of life (QoL), and healthcare-seeking behaviors of women with UI in South Korea. The only available data are from rural areas and sanatoriums [3,4,5]. The aforementioned issues need to be addressed in order to promote health and organize the healthcare services related to UI. Therefore, we undertook the present study using data from the Korea National Health and Nutrition Examination Survey IV (KNHANES) to investigate information about adult female UI.

To the best of our knowledge, this is the first study evaluating the prevalence of female UI in South Korea. The prevalence of UI in this study was 7.9%, and this finding is similar to other Asian population studies that reported prevalence rates ranging from 4.8% to 13.0% [10,11]. According to the age group, the prevalence rates of UI among women over the ages of 40 and 60 years were 10.1% and 10.3%, respectively. This finding was lower than the overall UI prevalence rates reported in Japanese women over the age of 40 years (53.7%) [12] and Taiwanese women aged 65 years or older (27.7%) [13]. However, it is important to note that the response rate of the Japanese survey was 53% and data were collected by mailed survey. In addition, the Taiwanese study only included women over the age of 65 years, and population sampling was performed by randomly sampled town populations. These factors may account for the difference in the observed study results.

Parity, age, and obesity are the three most thoroughly studied factors associated with UI [14,15,16]. In the present study, multivariate analysis identified age, BMI, and marriage as significant independent risk factors for UI. We were unable to assess parity as a risk factor because this information was not available in KNHANES IV. However, marital status, which is related to parity, showed a significant association with UI. The number of unmarried mothers in Korea is lower than that in western countries, and Korean traditions dictate that childbirth should follow marriage. Thus, marriage could be interpreted as a proxy for parity in this study. The results of this study may be helpful in identifying cases of UI when establishing a health policy for women with UI in Korea.

In this study, hypertension, diabetes, and stroke, which were thought to be associated with neurogenic bladder dysfunction, were not related to UI. We were unable to study the subtypes of UI because of the lack of this data. This may explain why hypertension, diabetes, and stroke were not identified as risk factors in this study. Further follow-up studies are required to elucidate these risk factors.

Compared to the prevalence rate of UI in Korean women, the consultation rate for UI is significantly lower, which is concordant with the pattern observed worldwide. A recent review article reported that only one in four women with UI in the United States and one in three women in Europe had sought medical care for UI [15,17]. A study of UI in Japanese women showed that only 3% had ever consulted doctors or other healthcare professionals [12,16]. Chinese data show that the consultation rate was 25%. This low consultation rate may be explained by the common misconception that UI is not a disease, but a natural consequence of aging, and that UI is not treatable.

In this study, UI was associated with an impaired QoL. After adjusting for potential confounders, impaired mobility, usual activity, pain/discomfort, and anxiety/depression were still associated with UI. A cross-sectional study from Turkey reported that 87.2% of women indicated that UI has a negative impact on their QoL [2]. Another study from the United States reported that the UI group was almost twice as likely to feel depressed as the non-UI group, and that UI had a significant negative impact on all aspects of QoL after adjusting for comorbidities and demographic differences [18]. The aforementioned results collectively support the finding that UI is associated with an impaired QoL, regardless of ethnicity and nationality.

The success rate of UI treatment has been reported to be very high. In up to 70% of women with mild stress UI, pelvic floor (Kegel) exercises can result in better control of the bladder when coughing, laughing, sneezing, or exercising [19]. In addition, long-term follow-up studies of surgical treatment (tension-free vaginal tape) for severe stress UI report that the cure rate ranges from 77% to 84.7% [20,21]. Furthermore, diverse treatment options (anticholinergics, alpha-blocker, botulinum toxin A, and neuromodulation) are available based on the patient's condition and the type of UI (urge, mixed, overflow, and functional/neurogenic UI) [22]. Treatment of UI means improving the patient's QoL [23,24]. However, compared with the prevalence rate of UI in Korean women, the consultation rate for UI is significantly low. Recently, the Health Insurance Review and Assessment Service reported that the number of anti-incontinence surgeries have increased from 5,944 cases in 2001 to 44,691 cases in 2006. Despite this increase in the number of surgeries, the consultation rate for UI remains low. Therefore, we think that a more efficient health policy is required for women with UI in Korea.

The present study had several limitations. First, the cross-sectional nature of the dataset makes causal inferences problematic. Second, we cannot elucidate the relationship between UI and parity, which is a well-known risk factor for UI. In addition, we could not study the subtypes of UI, as this information was not available. Nevertheless, we think that our study provides meaningful results, as this is the first study to elucidate the prevalence, risk factors, healthcare-seeking behaviors, and QoL of women with UI in Korea.

In conclusion, UI is a common disease and is significantly associated with QoL. Compared to the prevalence rate of UI in Korean women, the consultation rate for UI is significantly lower. Our results suggest the importance of developing preventive measures and treatment policies for UI.