Validation of the Chinese version of the Pelvic Floor Distress Inventory-20 (PFDI-20) according to the COSMIN checklist.

INTRODUCTION AND HYPOTHESIS: The objective of this study was to translate the short version of the Pelvic Floor Distress Inventory (PFDI-20) into Chinese and to evaluate its psychometric properties in Chinese women with symptomatic pelvic floor dysfunction according to the Consensus-Based Standards for the Selection of Health Status Measurement Instruments (COSMIN) checklist.

METHODS: Between October 2017 and May 2018, a cross-sectional analysis of the clinical data of 126 patients who met the inclusion criteria was performed. The patients completed the questionnaires at the baseline (T1), 1-2 weeks later (T2), and 3 months after surgery (T3). Reliability testing included internal consistency, test-retest reliability, and measurement error. The methodical tests for validity were content validity, criterion validity, construct validity, and hypothesis testing. Responsiveness was also taken into consideration.

RESULTS: One hundred twenty-six patients completed all questionnaires. Internal consistency, measured by Cronbach's alpha value, was good, and the test-retest reliability was high, with an intraclass correlation coefficient (ICC) of 0.99. Construct validity was verified by factor analysis. All assumptions were confirmed, and there were no ceiling or floor effects in this study. Spearman's correlation coefficient between the PFDI-20 and the Pelvic Floor Impact Questionnaire (PFIQ-7) was 0.867, showing a significant correlation. Furthermore, the minimal important change (MIC) of 50.0 was less than the smallest detectable change (SDC) of 18.36, indicating the sufficient responsiveness.

CONCLUSIONS: The Chinese version of the PFDI-20 developed in this study is a reliable and valid instrument that provides good responsiveness to clinical changes.