Exploring the impact of changes in neurogenic urinary incontinence frequency and condition-specific quality of life on preference-based outcomes

Many trials do not measure quality-adjusted life years (QALYs). Therefore, decision analysts often map condition-specific outcomes to preference scores. We estimated the relationship between changes in preference scores and commonly reported condition-specific outcomes in patients with urinary incontinence (UI) due to neurogenic detrusor overactivity. In 59 patients recruited to a neurogenic UI trial, clinical outcomes (UI episodes), condition-specific quality of life (Incontinence Quality of Life Instrument (I-QOL)), and SF-6D preference scores were measured at enrollment and 24 weeks. We used multiple linear regression to estimate the impact on SF-6D scores of 50; 50-99 and 100% reductions in UI episodes and a 10-point improvement in I-QOL. By 24 weeks, mean (95% CI) daily UI episodes fell by 0.85 (0.04, 1.3) and mean I-QOL scores improved by 18 (12, 24). SF-6D scores increased by 0.03 (0.003, 0.058), due to improvements in role limitations. A a parts per thousand yen 50% reduction in UI episodes was achieved by 49% of patients and corresponded to a 0.09 (0.02, 0.16) SF-6D increase. A a parts per thousand yen 10-point increase in I-QOL was attained by 65% of patients and was associated with a 0.05 (-0.02, 0.12) SF-6D increase. These estimates provide preliminary data for decision analysts wishing to map neurogenic UI outcomes to preference scores.