Psychometric Properties of the Patient Reported Outcomes Burdens and Experiences (PROBE) Questionnaire

Objective:To assess the psychometric properties of The Patient Reported Outcomes, Burdens and Experiences (PROBE) questionnaire.

Methods: This study was a cross-sectional, multi-national study. Participants were enrolled if they were 10 years or older and patients with hemophilia A or B or people without bleeding disorder. Participants were invited through non-governmental hemophilia patient organizations in 17 countries between 04/08/2015 and 12/28/2015, and completed the PROBE questionnaire. The following psychometric properties: item responses, missing data, floor and ceiling effects, exploratory factor analysis, and internal consistency reliability were examined. A PROBE Score was derived and assessed for its convergent and known groups validity.

Results: The study enrolled a total of 677 participants with median age of 40.0 (interquartile range 26.0 to 54.5) years, 71.9% male. Missing data was up to 2.5% for the section concerning patient reported outcomes (PROs). More than 15% of participants presented floor effect for all items but two, and a ceiling effect for two items. Factor analysis identified three factors explaining the majority of the variance. Cronbach's alpha coefficient indicated good internal consistency reliability (0.83). PROBE items showed moderate to strong correlations with corresponding EQ-5D-5L domains. The PROBE Score has a strong correlation (r=0.72) with EQ-5D-5L utility index score. The PROBE Score has a discriminative validity among known groups.

Conclusions: The results of this study suggest that PROBE is a valid questionnaire for evaluating PROs in people with hemophilia, as well as control population. The discriminative property of PROBE will allow its use in future clinical trials, longitudinal studies, health technology assessment studies, routine clinical care or registries.