Norwegian translation, and validation, of the Pelvic Floor Distress Inventory (PFDI-20) and the Pelvic Floor Impact Questionnaire (PFIQ-7)

The goal was to translate into Norwegian, and validate, short versions of the Pelvic Floor Distress Inventory (PFDI-20) and the Pelvic Floor Impact Questionnaire (PFIQ-7) using a sample of women with symptomatic pelvic organ prolapse and pelvic floor dysfunction. Modified European Organization for Research and Treatment of Cancer Guidelines were used for translation and cultural adaptation. Of 212 eligible Norwegian women who consented to participate, 205 completed the questionnaires, of whom 50 were retested after 1 - 3 weeks, and 76 were tested 6 months after surgery. Reliability, validity and responsiveness were evaluated. Additionally, interpretability, the smallest detectable change, the standard error of measurement, floor and ceiling effects, and the percentages of missing items are reported. Reliability ranged from 0.66 to 0.93 and intraclass correlation coefficients from 0.85 to 0.94. Both construct validity and responsiveness were found to be adequate. The responsiveness of the PFDI-20 was further supported by areas under the curve above 0.70. Estimates were lower for the PFIQ-7. The smallest detectable changes at the individual level were 15 - 21 % and 17 - 27 % for the PFDI-20 and PFIQ-7, respectively. The absolute values of the minimal important changes in the total scores were 48 and 47, respectively. No floor or ceiling effects were evident in the distributions of the PFDI-20 and PFIQ-7 total scores. The translated questionnaires provided adequate reliability, validity and good responsiveness to change. These short versions of the PFDI and PFIQ are robust measuring instruments that will enable symptom severity and health-related quality of life to be evaluated in the Norwegian context.