Part B: evaluation of measurement properties of the included PROMs

Descriptions of terminology for measurement properties are provided in online supplemental appendix 3. Each measurement property was evaluated in three separate sub-steps:

Two authors (SAS and SGFA) independently evaluated the measurement properties in each article against the COSMIN Risk of Bias checklist. A priori hypotheses for construct validity and responsiveness were set (online supplemental appendix 4, table 1). Study quality was assessed separately for each measurement property using a four-point rating system (very good, adequate, doubtful or inadequate). The ‘worst score counts’ principle was used, where the overall rating for each measurement property is given by the lowest rating of any standard in the box.²⁵

Two authors (SAS and SGFA) independently extracted data on: PROM characteristics (intended construct for measurement, measurement properties, method of administration), study sample (number of patients, patient demographics, diagnosis) and study details (setting, country, language). The few disagreements were resolved through discussion. The results from each study on a measurement property were assigned a quality rating as: sufficient (+), insufficient (−) or indeterminate (?).

This section refers to rating the quality of the PROM as a whole. PROMs were qualitatively summarised and assigned a four-point quality rating. A modified Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach (omitting publication bias) was used to assign evidence quality as high, moderate, low or very low.²⁶