Discriminant validity, responsiveness and reliability of the rheumatoid arthritis-specific Work Productivity Survey (WPS-RA)

Table 4 WPS-RA baseline responses by HAQ-DI and SF-36: home productivity and daily activities of all randomly assigned subjects in the modified intent-to-treat population

Instrument^a	Number of days of household work missed over the previous month, mean (SD)		Number of days with household productivity ≤ 50% over the previous month, mean (SD)		Number of days of missed family, social, or leisure activities over the previous month, mean (SD)		Number of days with outside help over the previous month, mean (SD)		Rate of arthritis interference with household WP^b over the previous month, mean (SD)
	Worst	Best	Worst	Best	Worst	Best	Worst	Best	Worst	Best
HAQ-DI (cutoff 0.75 and 1.75)	12.5 (10.79)	6.4^c (8.01)	14.0 (10.35)	9.4^c (9.53)	5.1 (7.80)	3.6^c (6.56)	1.5 (4.90)	1.1 (4.57)	7.0 (2.42)	5.1^c (2.82)
	n = 116	n = 96	n = 115	n = 96	n = 116	n = 96	n = 114	n = 95	n = 113	n = 95
SF-36 PCS (cutoff 21.98 and 33.0)	13.7 (10.91)	3.4^c (5.13)	14.7 (11.21)	6.2^c (7.06)	5.7 (7.94)	1.7^c (3.26)	1.4 (4.72)	0.5^c (1.24)	7.0 (2.77)	4.0^c (2.52)
	n = 55	n = 52	n = 54	n = 52	n = 55	n = 52	n = 55	n = 51	n = 55	n = 51
SF-36 MCS (cutoff 35.31 and 54.07)	14.0 (11.05)	4.7^c (6.16)	15.9 (10.13)	5.8^c (7.69)	6.9 (8.24)	0.6^c (1.19)	1.5 (4.74)	0.8 (4.20)	7.1 (2.51)	4.1^c (2.73)
	n = 53	n = 53	n = 53	n = 53	n = 53	n = 53	n = 52	n = 52	n = 52	n = 52

^aCutoff points represent first and third quartiles of baseline scores; 'worst' group (HAQ-DI score ≥ third quartile; SF-36 score ≤ first quartile) and 'best' group (HAQ-DI score ≤ first quartile, SF-36 ≥ third quartile). ^bScore on a scale of 0 to 10 points (0 = no interference and 10 = complete interference). WPS-RA recall period is 1 month; ^cP value ≤ 0.001 best versus worst; P values were obtained using the non-parametric bootstrap-t method. HAQ-DI, Health Assessment Questionnaire – Disability Index; SD, standard deviation; SF-36, Short Form-36 health survey; SF-36 MCS, Short Form-36 health survey – Mental Component Summary; SF-36 PCS, Short Form-36 health survey – Physical Component Summary; WP, work productivity; WPS-RA, Work Productivity Survey – Rheumatoid Arthritis.

ISSN: 1478-6362