The minimum important differences for the urinary scales of the Pelvic Floor Distress Inventory and Pelvic Floor Impact Questionnaire.
OBJECTIVE
We sought to estimate the minimum important difference (MID) for the Urinary Distress Inventory (UDI), UDI-stress subscale of the Pelvic Floor Distress Inventory, and Urinary Impact Questionnaire (UIQ) of the Pelvic Floor Impact Questionnaire.


METHODS
We calculated MID using anchor- and distribution-based approaches from a randomized trial for nonsurgical stress incontinence treatment. Anchors included a global impression of change, incontinence episodes from a urinary diary, and the Incontinence Severity Index. Effect size and standard error of measurement were the distribution methods used.


RESULTS
Anchor-based MIDs ranged from -22.4 to -6.4 points for the UDI, -16.5 to -4.6 points for the UDI-stress, and -17.0 to -6.5 points for the UIQ. These data were supported by 2 distribution-based estimates.


CONCLUSIONS
Reasonable estimates of MID are 11, 8, and 16 points for the UDI, UDI-stress subscale, and UIQ, respectively. Statistically significant improvements that meet these thresholds should be considered clinically important.
Obstetrics, Gynecology, and Women's Health Institute, Cleveland Clinic, Cleveland, OH, USA.
Matthew D
MD
Barber
Cathie
C
Spino
Nancy K
NK
Janz
Linda
L
Brubaker
Ingrid
I
Nygaard
Charles W
CW
Nager
Thomas L
TL
Wheeler
D000328:Adult; D000342:Affective Symptoms / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008875:Middle Aged; D017773:Pelvic Floor; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014550:Urinary Incontinence, Stress / Q000503:physiopathology / Q000523:psychology / Q000628:therapy