Table 2 Questionnaires used in KetCRPS-2 study. Adapted from the Core Outcome Measurement set for complex regional PAin syndrome Clinical sTudies (COMPACT) [19]

Global Perceived Effect (GPE) [20]

The Global Perceived Effect asks the patient to rate, on a numerical scale, how much their condition has improved or deteriorated since some predefined time point.

T2, T3, T4

PROMIS-29 Profile version 2.1 [29]

Assesses 7 domains, each with 4 questions: depression, anxiety, physical function, pain interference, fatigue, sleep disturbance, and ability to participate in social roles and activities.

T0, T3

Short-form McGill Pain Questionnaire-2 (SF-MPQ-2) [30]

Six neuropathic items capturing the quality of pain

T0, T3

Pain Catastrophizing Scale [31]

To measure how catastrophizing affects the pain experience.

T0, T3

EQ-5D-5L [21]

To measure health state, comprising mobility, self-care, usual activities, pain/discomfort, anxiety/depression

T0, T3, T4

Pain Self-Efficacy Questionnaire [32]

The respondent considers how confident they are performing each activity, while taking their pain into account

T0, T3

CRPS severity score [14]

CRPS symptoms and signs based on the Budapest diagnostic clinical criteria

T0, T3