Table 1

Comparative measurement range of five physical function instruments with 90% reliability

PF-10

HAQ

PROMIS PF-10

PROMIS PF-20

PROMIS PF CAT-10


Floor

-2.5

-4.5

-2.9

-4.5

-4.5

Ceiling

-0.2

-0.4

0.2

0.2

1.2

Range

2.3

4.1

3.1

4.8

5.7


Each unit below zero (the population mean) is scored as a negative of standard deviations toward the floor, and each unit above zero (the population mean) is a standard deviation in the direction of the ceiling "range" as the algebraic sum of standard deviations of positive and negative [15]. 1 Instruments: PF-10 - 10-item physical function scale of the SF-36 [3]; HAQ - 20-item Health Assessment Questionnaire [2]; PROMIS PF-10 - PROMIS PF-10, 10-item Physical Function assessment form [5]; PROMIS PF-20 - PROMIS PF-20, 20-item physical function assessment form [5]; PROMIS PF CAT-10 - PROMIS PF 10-item Computerized Assessment Testing [5]

Bruce et al. Arthritis Research & Therapy 2013 15:R144   doi:10.1186/ar4327

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