Aim: 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.
Methods: 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.
Results: 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.
Conclusions: 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.