Patient-reported outcome measures in core outcome sets targeted overlapping domains but through different instruments

There is no comprehensive assessment of which patient-reported outcomes (PROs) are recommended in core outcome sets (COS), and how they should be measured. The aims of this study are to review COS that include patient-reported outcomes measures (PROMs), identify their target health domains, main characteristics, and their overlap within and across different disease areas.

We selected COS studies collected in a publicly available database that included at least one recommended PROM. We gathered information on study setting, disease area, and targeted outcome domains. Full-text of recommended instruments were obtained, and an analysis of their characteristics and content performed. We classified targeted domains according to a predefined 38-item taxonomy.

Overall, we identified 94 COS studies that recommended 323 unique instruments, of which: 87% were included in only one COS; 77% were disease-specific; 1.5% preference-based; and 61% corresponded to a full questionnaire. Most of the instruments covered broad health-related constructs, such as global quality of life (25%), physical functioning (22%), emotional functioning and wellbeing (7%).

The wealth of recommended instruments observed even within disease areas does not fit with a vision of systematic, harmonized collection of PROM data in COS within and across disease areas.