The minimal important difference of the Australian Pelvic Floor Questionnaire

The aim of this study was to establish the minimal important difference (MID) of the Australian Pelvic Floor Questionnaire (APFQ) in women undergoing surgery for stress urinary incontinence or symptomatic pelvic organ prolapse. A further aim was to estimate dysfunction scores dependent on the bothersomeness in a community cohort.

The APFQ was completed before and 6 weeks after pelvic floor surgery by 183 women (n = 80 suburethral tape insertion; n = 103 laparoscopic sacrocolpopexy). Distribution and anchor-based methods were used to establish the effect size, standardised response mean and MID (calculated as the difference between women who stated no change or a little better in the Patient Global Impression of Improvement [PGI-I]). In a community cohort of 470 women aged 42-80 years, the APFQ was analysed according to disclosed bothersomeness.

For the suburethral tape group, the effect size in the bladder domain was 1.5 and the PGI-I-based MID 1.3. For the POP surgery, group the effect size in the prolapse domain was calculated at 2.2 and the PGI-I-based MID at 1.0. The domain scores for women who declared no bother were significantly different from those who were a little bothered (bladder domain 2.2 vs 4.0, bowel 0.6 vs 1.7, POP 0.1 vs 3.2, sex 1.8 vs 3.0) with wide variations.

The MID of the APFQ ranged from 1.0 to 1.3 in the domains after POP or continence surgery respectively. This is corroborated by the differences in domain scores from community-based women who were bothered versus not bothered by pelvic floor symptoms.