Validation of a severity index in female urinary incontinence and its implementation in an epidemiological survey.
STUDY OBJECTIVE--The aim was to validate a simple severity index of female urinary incontinence for subsequent use in an epidemiological survey. DESIGN--The index was created by multiplying the reported frequency (four levels) by the amount of leakage (two levels). The resulting index value (1-8) was further categorised into slight (1-2), moderate (3-4), and severe (6-8). It was validated against a 48 hour "pad weighing" test. Thereafter, an anonymous postal questionnaire survey was performed and the index was used to assess the severity of the leakage. A question about the impact of incontinence was also included. SETTING--The outpatient clinic of the Department of Gynaecology and Obstetrics, Trondheim University Hospital and the rural community of Rissa, Norway. PARTICIPANTS--Altogether 116 incontinent women referred to the clinic by their GP and all 2366 adult women living in Rissa. RESULTS--The difference in median pad weights between moderate and slight incontinence was 9g/24h (95% confidence interval 0-27). The corresponding difference between severe and moderate incontinence was 17g/24h (95% CI 5-30). In the epidemiological survey 29.4% reported urinary incontinence (response rate 77%). The prevalence tended to be highest in middle life and old age. Forty six per cent were classified as slight, 27% moderate, and 27% severe. There was a strong correlation between severity and impact (R = 0.59, p < 0.001). CONCLUSION--The severity index may be a useful tool for assessing the severity of female urinary incontinence in epidemiological surveys. It is confirmed that urinary incontinence is very prevalent in adult women, but most should not be regarded as potential patients.