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.