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Table 2 Differences in responses to extremes of response options between selected legacy (original) and rewritten PF-10a a and HAQ-DI b items

From: Better assessment of physical function: item improvement is neglected but essential

   PF-10  
  Legacyc Rewrittend
  Original Stem: During a typical day does your health now limit you in ... If so, how much? New Stem: How much does your health now limit you ...
Items Total Completing Item
(n)
Yes, limited
a lot (%)
No, not limited at all
(%)
Total Completing Item
(n)
Cannot do
(%)
Not at
all
(%)
   1. Bathing and dressing yourself 81 0 65 74 4 61
   2. Climbing one flight of stairs 77 8 55 71 24 41
   3. Walking several hundred yards 75 20 55 81 19 48
   4. Walking more than a mile 81 32 33 78 31 22
   5. Vigorous activities (running, lifting heavy objects, participating in strenuous sports       
Mean instrument score: All 10 PF-10 items 19.8 44.9   23.6 35.6*
   HAQ-DI    
  Legacy c Rewritten d
  Original stem: Over the past week, have you been able to ... New stem: Are you able to ...
  Total completing item
(n)
Unable to do (%) Without any difficulty (%) Total completing item
(n)
Unable to do
(%)
Without any difficulty (%)
1. Lift full cup or glass to mouth 81 0 91 78 0 88
2. Climb up five steps 81 2 69 75 4 71
3. Get in and out of a car 71 3 61 71 1 54
4. Reach and get down a 5 lb. object from above your head 78 10 62 81 9 48
5. Chores such as vacuuming/yard work 74 18 35 71 21 30
Mean instrument score: All 20 HAQ-DI items 4.8 73.2   4.7 66.3**
  1. aPF-10: 10-item physical function scale of the SF-36.
  2. bHAQ-DI: Health Assessment Questionnaire Disability Index.
  3. Response option sets:
  4. cLegacy PF-10: Yes, limited a lot; yes, limited a little; no, not limited at all
  5. dRewritten PF-10: Not at all, very little, somewhat, quite a lot, cannot do
  6. eLegacy HAQ-DI: Without any difficulty, with some difficulty, with much difficulty, unable to do
  7. fRewritten HAQ-DI: Without any difficulty, with a little difficulty, with some difficulty, with much difficulty, unable to do
  8. * P < 0.01; ** P < 0.05 between Legacy and Rewritten items.