Further validation of the short form versions of the pelvic floor Distress Inventory (PFDI) and pelvic floor impact questionnaire (PFIQ)

Abstract

To evaluate validity and responsiveness of PFDI and PFIQ short forms across four multi-center studies and develop conversion formulas between short and long versions. 1,006 participants in four prospective studies of pelvic floor disorders completed long versions of the PFDI, PFIQ, and SF-36 (or SF-12) at baseline and 3 and 12 months after treatment. Responses were used to calculate scores for the short versions. We calculated correlations between scale versions using Pearson's correlation coefficient and compared their relative responsiveness using the standardized response mean. PFDI and PFIQ short form scale scores demonstrated excellent correlations with long versions and similar responsiveness. Responsiveness was good to excellent for PFDI-20 urinary and prolapse scales, moderate for PFDI-20 colorectal scale and each of the PFIQ-7 scales, and poor for SF-36 (or SF-12) summary scores. Conversion formulas demonstrated excellent goodness of fit. The long and short forms of the PFDI and PFIQ correlate well and have similar overall responsiveness in participants from four different prospective multicenter studies consisting of diverse patient populations with a broad range of pelvic floor disorders. The short forms provide a reliable and valid alternative in situations where reduced response burden is desired.