Table 1.

Patient-reported instruments used in the clinical trial

Feature	WOMAC15	BPI-SF18	BFI19
Number of items	24	15*	9
Response format	5-point scale: none, mild, moderate, severe, extreme	0–10 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 period	48 hours	24 hours	24 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.