Validation of the Sinhala translations of the Pelvic Floor Distress Inventory and the Pelvic Floor Impact Questionnaire in a Sri Lankan population

Abstract

This study was to translate and validate self-reported questionnaires, the Pelvic Floor Distress Inventory (PFDI-20) and the Pelvic Floor Impact Questionnaire (PFIQ-7) into Sinhala, the language spoken by the majority of Sri Lankans. A total of 270 patients were enrolled in this study. Two groups were selected with pelvic organ prolapse (POP)—cases and without POP—controls in a ratio of 1:2 respectively. Psychometric properties of the questionnaires were assessed using content validity, face validity, convergent validity, construct validity, internal consistency, and reliability. Pelvic Organ Prolapse Quantification (POP-Q) was used as the test to quantify POP. Excellent content validity was demonstrated by a content validity ratio for all items by experts. Face validity was confirmed by non-experts using a five-point Likert scale and Mann–Whitney U test for all items. Internal consistency was found to be high for both questionnaires (Cronbach’s alpha >0.8) in all items. Construct validity was assessed by receiver-operating characteristic curves and the area under the curve is above 0.5 in all items in both questionnaires. Convergent validity was assessed using Pearson coefficient correlation, which was above 0.8 for all subscales. Reliability was low for all subscales in the paired t test. The Sinhala versions of PFDI-20 and PFIQ-7 were valid, consistent, responsive, but have low reliability in the Sri Lankan setting.