Agreement between patient global impression scale of improvement, pelvic floor distress inventory and 15D in measuring the outcome of pelvic organ prolapse surgery

Abstract

Aims: To evaluate the correlation between three commonly used patient-reported outcome measures, two generic and one condition-specific instrument, in assessing the change in health-related quality of life following pelvic organ prolapse surgery.

Methods: The generic health-related quality of life measure 15-dimensional instrument (15D), Patient Global Impression of Improvement (PGI-I), and prolapse-specific Pelvic Floor Distress Inventory (PDFI-20) were used to assess the effectiveness of pelvic organ prolapse surgery in the national FINPOP study of 3535 surgeries (83% of all pelvic organ prolapse operations) performed in Finland in 2015. Spearman correlations between PGI-I, change in 15D and its dimensions and change in PFDI-20 and its subscales over a 2-year follow-up were investigated. The proportion of concordant ratings was also studied by investigating the proportion of women rated similarly (worse/no change/better/much better) by two instruments according to validated cutoffs.

Results: Among 2248 women for whom the 2-year change in all instruments could be measured, changes in PFDI-20 and 15D and its dimensions were weak (ρ < 0.2 for all except excretion; ρ = 0.39 and sexual activity; ρ = 0.27). PFDI-20 change (ρ = 0.39) and its subscales (ρ = 0.19-0.40, all P < .001) were more strongly correlated with PGI-I. The proportion of fully concordant ratings were higher for PFDI-20 and PGI-I (50.6%) than for PFDI-20 and 15D (33.0%).

Conclusion: The weak correlations between 15D, PGI-I, and PDFI-20 observed in this study show that the quantified health gains are strongly dependent on the chosen patient-reported outcome measures. This demonstrates the importance of using condition-specific sensitive outcome measures in assessing the impact of surgical treatment in pelvic organ prolapse.

Keywords: 15D; HRQoL; Health-related Quality of Life; PFDI-20; PGI-I; POP; PROM; Patient Global Index of Improvement; Patient-Reported Outcome Measure; Pelvic Floor Distress Inventory; QoL; Quality of Life; pelvic organ prolapse; pelvic reconstructive surgery; surgery; urogynecology.