Internal structure and classification of pelvic floor dysfunction distress by PFDI-20 total score

Purpose To evaluate the internal structure (structural validity and internal consistency) and propose a classification for the distress caused by the presence of pelvic floor dysfunction (PFD) symptoms based on the total score of the Pelvic Floor Distress Inventory (PFDI-20). Methods Cross-sectional study conducted with Brazilian women over 18 years of age. Exploratory and confirmatory factor analysis were performed with Parallel Analysis and to test three models to compare them with the Root Mean Square Error of Approximation (RMSEA) and Comparative Fit Index (CFI). Internal consistency was calculated using Cronbach's alpha. Partial credit model (PCM) was performed to classify the total score of the PFDI-20. Results Data from 237 women (49.62 +/- 16.95 years) were analyzed. The one-dimensional structure had 43.74% of the explained variance with alpha = 0.929. The one-dimensional model was the most appropriate (CFI = 0.987 and RMSEA = 0.022). The total PFDI-20 score was classified as the absence of symptoms (score zero), symptoms with mild distress (1 to 15 points), symptoms with moderate distress (16 to 34 points), and symptoms with severe distress (35 to 40 points). Conclusion The PFDI-20 has an one-dimensional structure and the distress caused by the presence of PFD symptoms can be classified as mild, moderate and severe. Health professionals and future studies can use our classification to facilitate the understanding of the patient's health status and to obtain other analyses on the severity of the distress of the symptoms of PFD. Plain English summary There are limitations regarding the meaning of the total score of the Pelvic Floor Distress Inventory (PFDI-20) in clinical practice and scientific research. Thus, the aims of this study were to evaluate the internal structure (structural validity and internal consistency) and propose a classification for the distress caused by the presence of pelvic floor dysfunction (PFD) symptoms from the total score of PFDI-20. Cross-sectional study conducted with Brazilian women over 18 years of age. Data from 237 women (49.62 +/- 16.95 years) were analyzed. The PFDI-20 has one-dimensional structure and the distress caused by the presence of PFD symptoms can be classified as mild, moderate and severe.