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Table 1 Reference questionnaires

From: Development of the Japanese Core Outcome Measures Index (COMI): cross-cultural adaptation and psychometric validation

Questionnaire Content Scale Item number Score range COMI domains expected to correlate strongly
EQ-5D [18] General health status     Summary, QOL
 The descriptive system Mobility, self-care, usual activities, pain/discomfort, and anxiety/depression 3-point Likert 5 −0.111–1.000a  
 EQ-VAS   VAS 1 0–100b  
RDQ [19] Physical disability due to low back pain Dichotomous (yes or no) 24 0–24c Summary, Function, Disability
SF-8 [20] General health-related quality of life 5- or 6-point Likert 8   
 PCS     5.32–70.69d Summary, Pain, Function, Symptom-specific well-being, QOL
 MCS     10.11–74.51d Symptom-specific well-being, QOL
STarT [21] Potentially modifiable prognostic indicators
Five questions related to the psychological factors constitute the sub-score
5-point Likert and Dichotomous (agree or disagree) 9 0–9e Summary, Pain, Function, Disability
  1. aCalculated using the value set for the Japanese population [34]. The score of 1 denotes “full health” and 0 “death”
  2. bThe score of 0 indicates worst imaginable health state and 100 best possible health state
  3. cA higher score indicates greater disability
  4. dCalculated based on a norm-based scoring method given in the instrument guidelines [21]. A higher score indicates better health
  5. eA total score of 0–3 indicates low prognostic risk; a total score of ≥4 with sub score of ≤3, medium prognostic risk; sub score of ≥4, high prognostic risk
  6. EQ-5D: the EuroQol 5 Dimension; VAS: visual analogue scale; RDQ: Roland Morris Disability Questionnaire; SF-8: Short Form 8™ Health Survey; PCS: physical component summary; MCS: mental component summary; STarT: the Keele STarT Back Screening Tool