How is your proctology patient really doing? Outcome measurement in proctology: development, design and validation study of the Proctoprom

Background The aim of the present study was to develop and evaluate the reliability and validity of proctology patient-reported outcome measurements (PROM): Proctoprom. Methods Development of the Proctoprom was based on interview rounds with experts (n = 4) and patients (n = 19) in open informal interview rounds regarding content and form. Once consensus was achieved on five items, data were collected between July 2014 and August 2016 from 991 patients recruited consecutively in a specialized proctology center. Reliability, construct validity and responsiveness of the PROM were determined through exploratory factor analysis, test-retest analysis and anchor-based hypothesis testing. We also estimated discriminant validity, standard error of measurement (SEM), minimal detectable change (MDC95%) and minimal clinically important difference (MCID). Results The five items loaded on one factor that reflected good internal consistency (Cronbach's alpha 0.81). Test-retest analysis showed good reliability with intraclass correlation of 0.81. Construct validity measurement resulted in AUCs of 0.85 and 0.90. Responsiveness measurement resulted in AUCs of > 0.76 for both hypotheses. SEM was estimated at 3.0 points and MDC at 4.8 points. We estimated an MCID of 10 points. Conclusions Proctoprom is a valid and reliable tool that is responsive to change and that meets consensus-based standards for the selection of health measurement instruments. It can be used to evaluate disease burden and effect of treatment in all adult proctology patients regardless of their proctologic diagnosis.