Psychometric analysis of international prostate symptom score for female lower urinary tract symptoms

Although the International Prostate Symptom Score (IPSS) has often been used for female lower urinary tract symptoms (FLUTS), the psychometric properties of IPSS for FLUTS have not been studied. We investigated the reliability and validity of IPSS for FLUTS.

Two samples were prepared. Sample A consisted of 227 women and 455 men who consulted a hospital doctor and sample B consisted of 519 women and 419 men who consulted a general practitioner. Eighty-nine percent of participants completed all IPSS items and quality of life index. Cronbach's alpha coefficients and Spearman's rho were calculated for reliability and validity assessment, respectively. A factor analysis was also conducted to explore the underlying structure.

Significant differences were found in age and each IPSS item score between the 2 samples. Cronbach's alpha of IPSS in women was approximately 0.8 in both samples, comparable to that in men. The relatively high Spearman's rho among most of IPSS voiding items and among most storage items and low Spearman's rho among most of the different categories described indicated good convergent and discriminant validity. The factor analysis showed 2 components in IPSS for FLUTES. The first was consistently related to IPSS items 1, 3, 5, and 6 and the second was related to IPSS items 2, 4, and 7. In men, however, IPSS item 4 comprised different components between samples A and B.

Although the subject background somewhat affects the psychometric properties, the IPSS can be relevant when used to examine women, as well as men.