Psychometric properties of the pelvic organ prolapse symptom score

OBJECTIVE: To assess the internal consistency, construct validity and sensitivity to change of a pelvic organ prolapse symptom score (POP-SS). DESIGN: Analysis of data from three prolapse studies, including symptomatic and asymptomatic women who completed the POP-SS. SETTING: (1) A community setting in New Zealand, (2) two gynaecology outpatient departments in Scotland and (3) a gynaecological surgery department in Scotland. POPULATION OR SAMPLE: (1) Participants from a survey of postnatal women at 12-year follow up, invited to complete a prolapse questionnaire and have prolapse assessment, (2) new gynaecology outpatients presenting with prolapse symptoms, randomised to pelvic floor muscle training (PFMT) or control and (3) women having anterior and/or posterior prolapse surgery, randomised to mesh insert or no mesh. METHOD: Data were analysed to assess internal consistency, construct validity and sensitivity to change of the POP-SS. MAIN OUTCOME MEASURES: Cronbach's alpha, significance of differences in POP-SS scores between studies and significance of difference in POP-SS scores pre- to post-intervention. RESULTS: For internal consistency, Cronbach's alpha ranged from 0.723 to 0.828. Women having surgery had higher POP-SS scores than those having conservative management (mean difference 5.0, 95% CI 3.1-6.9), who in turn had higher scores than the asymptomatic women (mean difference 5.9, 95% CI 4.4-7.4). Significant differences in POP-SS score were detected after surgery and PFMT. The improvement due to surgery was significantly greater than that associated with PFMT (z =-3.006, P = 0.003). CONCLUSION: The POP-SS has good internal consistency and construct validity and is sensitive to change.