Development and evaluation of a crosswalk between the SF-36 physical functioning scale and Health Assessment Questionnaire disability index in rheumatoid arthritis

ten Klooster, Peter M; Oude Voshaar, Martijn AH; Gandek, Barbara; Rose, Matthias; Bjorner, Jakob B; Taal, Erik; Glas, Cees AW; van Riel, Piet LCM; van de Laar, Mart AFJ

doi:10.1186/1477-7525-11-199

Table 2 Rasch-based crosswalk for transforming PF-10 scores into HAQ-DI scores and vice versa

From: Development and evaluation of a crosswalk between the SF-36 physical functioning scale and Health Assessment Questionnaire disability index in rheumatoid arthritis

HAQ standard scoring (with aids and devices)				HAQ alternative scoring (without aids and devices)
Observed	Predicted	Observed	Predicted	Observed	Predicted	Observed	Predicted
HAQ-SDI	PF-10	PF-10	HAQ-SDI	HAQ-ADI	PF-10	PF-10	HAQ-ADI
score	score*	score*	score	score	score*	score*	score
0.000	95 (54.9)	100 (57.0)	0.000	0.000	95 (54.9)	100 (57.0)	0.000
0.125	90 (52.8)	95 (54.9)	0.000	0.125	85 (50.7)	95 (54.9)	0.000
0.250	85 (50.7)	90 (52.8)	0.125	0.250	80 (48.6)	90 (52.8)	0.125
0.375	75 (46.5)	85 (50.7)	0.250	0.375	75 (46.5)	85 (50.7)	0.125
0.500	75 (46.5)	80 (48.6)	0.250	0.500	70 (44.4)	80 (48.6)	0.250
0.625	70 (44.4)	75 (46.5)	0.375	0.625	65 (42.3)	75 (46.5)	0.375
0.750	65 (42.3)	70 (44.4)	0.625	0.750	55 (38.1)	70 (44.4)	0.500
0.875	60 (40.2)	65 (42.3)	0.750	0.875	50 (36.0)	65 (42.3)	0.625
1.000	55 (38.1)	60 (40.2)	0.875	1.000	45 (33.9)	60 (40.2)	0.625
1.125	50 (36.0)	55 (38.1)	1.000	1.125	45 (33.9)	55 (38.1)	0.750
1.250	45 (33.9)	50 (36.0)	1.125	1.250	40 (31.8)	50 (36.0)	1.000
1.375	45 (33.9)	45 (33.9)	1.375	1.375	35 (29.7)	45 (33.9)	1.125
1.500	40 (31.8)	40 (31.8)	1.500	1.500	30 (27.6)	40 (31.8)	1.250
1.625	35 (29.7)	35 (29.7)	1.625	1.625	25 (25.5)	35 (29.7)	1.375
1.750	30 (27.6)	30 (27.6)	1.750	1.750	25 (25.5)	30 (27.6)	1.500
1.875	25 (25.5)	25 (25.5)	1.875	1.875	25 (25.5)	25 (25.5)	1.750
2.000	20 (23.4)	20 (23.4)	2.125	2.000	20 (23.4)	20 (23.4)	2.000
2.125	20 (23.4)	15 (21.3)	2.250	2.125	15 (21.3)	15 (21.3)	2.125
2.250	15 (21.3)	10 (19.2)	2.375	2.250	10 (19.2)	10 (19.2)	2.250
2.375	10 (19.2)	5 (17.0)	2.625	2.375	10 (19.2)	5 (17.0)	2.625
2.500	5 (17.0)	0 (14.9)	2.750	2.500	5 (17.0)	0 (14.9)	2.750
2.625	5 (17.0)			2.625	5 (17.0)
2.750	0 (14.9)			2.750	0 (14.9)
2.875	0 (14.9)			2.875	0 (14.9)
3.000	0 (14.9)			3.000	0 (14.9)

*Scores are original 0–100 transformed scale scores, 1998 US norm-based T-scores are presented between brackets.

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ISSN: 1477-7525

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