The minimal important change of the PRAFAB questionnaire in women with stress urinary incontinence: Results from a prospective cohort study

Abstract

To estimate the minimal important change (MIC) of the total PRAFAB questionnaire (PRAFAB-Q) score in women referred for physiotherapy intervention following primary or recurrent episodes of stress urinary incontinence. MIC values could be applied to individual patients and used as a threshold by which practitioners decide to continue, change or end a specific intervention. Data were derived from a prospective cohort study of 279 mainly Caucasian women. MIC values were determined by: (1) the 'mean change' method, (2) the ROC method, and (3) the 95% limit cut-off point, visualized by the 'anchor-based MIC distribution'. These MIC values were compared to the smallest detectable change (SDC) accounting for measurement error. The effect of initial baseline scores on the MIC was assessed. The results of all methods used to define the MIC ranged from 1.9 to 2.7 points (SDC = 1.6) for the non-severe and 3.6-4.1 (SDC = 2.3) for the severe stratified patients. All MIC estimates were larger than the measurement error as determined by the SDC. The total PRAFAB-Q score is a brief and simple outcome measure that easily can be used to monitor progress and to interpret meaningful improvement in individual women with stress UI in everyday clinical practice.