Table 1

Patient-reported instruments used in the clinical trial

FeatureWOMAC15BPI-SF18BFI19
Number of items2415*9
Response format5-point scale: none, mild, moderate, severe, extreme0–10 numerical rating scale (10 indicates worst pain severity/interference)0–10 numerical rating scale
(10 indicates worst fatigue severity/interference)
Scores reported (number of items)Pain (n=5)
Stiffness (n=2)
Physical function (n=17)
Total score (n=24)
Worst pain (average) (n=1)†
Worst pain (greatest) (n=1)†
Pain severity (n=4)
Pain interference (n=7)
Worst fatigue (average) (n=1)‡
Worst fatigue (greatest) (n=1)‡
Fatigue severity (n=3)
Fatigue interference (n=6)
Global fatigue (n=9)
Recall period48 hours24 hours24 hours
XLH-specific meaningful change (MCIDs)§≥−10.0 total score
≥−11.0 pain
≥−10.0 stiffness
≥−8.0 physical function16
≥−1.72 worst pain
≥−1.0 pain interference17
≥−1.5 worst fatigue
≥−1.2 global fatigue
≥−1.2 fatigue interference20
  • *BPI-SF has 15 items in total, 11 items contribute to the scores reported in this analysis.

  • †BPI-SF question 3 asks subjects to rate their pain at its worst in the last 24 hours on a scale of 0 (no pain) to 10 (pain as bad as you can imagine). This study reports worst pain (average score for question 3 over 8 days) and worst pain (greatest score for question 3 over 8 days).18 27 28

  • ‡BFI question 3 asks subjects to rate their fatigue at its worst in the last 24 hours on a scale of 0 (no fatigue) to 10 (fatigue as bad as you can imagine). This study reports worst fatigue (average score over 8 days) and worst fatigue (greatest score over 8 days).19

  • §A guide for interpreting the mean in a group of subjects rather than a change in an individual.21

  • BFI, Brief Fatigue Inventory; BPI-SF, Brief Pain Inventory-Short Form; MCID, minimal clinically important difference; WOMAC, Western Ontario and the McMaster Universities Osteoarthritis Index; XLH, X-linked hypophosphataemia.