Discriminant validity, responsiveness and reliability of the arthritis-specific Work Productivity Survey assessing workplace and household productivity in patients with psoriatic arthritis

Osterhaus, Jane T; Purcaru, Oana

doi:10.1186/ar4602

Table 4 Kendall association coefficients between WPS and clinical and HRQoL assessments at baseline (randomized set, observed cases)

From: Discriminant validity, responsiveness and reliability of the arthritis-specific Work Productivity Survey assessing workplace and household productivity in patients with psoriatic arthritis

	WPS question
	2: number of work days missed because of arthritis	3: number of days with work productivity reduced by one-half or more because of arthritis	4: rate of arthritis interference with work productivity on a scale of 0 to 10	5: number of days with no household work because of arthritis	6: number of days with household work productivity reduced by one-half or more because of arthritis	7: number of days missed of family, social, or leisure activities because of arthritis	8: number of days with outside help hired because of arthritis	9: rate of arthritis interference with household work productivity on a scale of 0 to 10
DAS28 (CRP)	0.16**	0.09	0.16**	0.22**	0.13**	0.15**	0.12*	0.24**
PASI^a	0.11	0.06	−0.02	−0.01	0.05	0	0.02	−0.04
HAQ-DI	0.25**	0.21**	0.32**	0.34**	0.26**	0.28**	0.22**	0.38**
SF-36 MCS	−0.16**	−0.16**	−0.22**	−0.23**	−0.24**	−0.34**	−0.24**	−0.28**
SF-36 PCS	−0.19**	−0.15**	−0.28**	−0.31**	−0.20**	−0.19**	−0.15**	−0.32**
SF-36 PF	−0.22**	−0.16**	−0.27**	−0.36**	−0.22**	−0.25**	−0.20**	−0.34**
SF-36 BP	−0.29**	−0.20**	−0.33**	−0.34**	−0.24**	−0.33**	−0.19**	−0.38**
SF-36 RE	−0.24**	−0.21**	−0.28**	−0.29**	−0.23**	−0.35**	−0.30**	−0.31**
SF-36 RP	−0.26**	−0.24**	−0.34**	−0.32**	−0.26**	−0.28**	−0.23**	−0.37**
SF-36 GH	−0.07	−0.09	−0.18**	−0.16**	−0.15**	−0.15**	−0.17**	−0.20**
SF-36 MH	−0.15*	−0.15*	−0.20**	−0.19**	−0.23**	−0.29**	−0.21**	−0.27**
SF-36 SF	−0.17**	−0.21**	−0.26**	−0.30**	−0.26**	−0.36**	−0.17**	−0.30**
SF-36 VT	−0.14*	−0.10*	−0.18**	−0.27**	−0.22**	−0.27**	−0.17**	−0.30**
PsAQoL	0.24**	0.23**	0.30**	0.28**	0.28**	0.37**	0.27**	0.35**
DLQI	0.11 ^#	0.03	0.06	0.08^#	0.09*	0.15**	0.08^#	0.10*
EQ-5D VAS	−0.09	−0.09	−0.19**	−0.15**	−0.13**	−0.14**	−0.12**	−0.20**

^aAssessed only in patients with at least 3% body surface area at baseline. **P ≤ 0.001. *P ≤ 0.01. ^#P ≤ 0.05.
WPS Questions 2 to 4 were assessed in employed patients only, whereas Questions 5 to 9 were assessed in all patients; Questions 4 and 9 are 0 to 10 scales, where 0 = no interference and 10 = complete interference. Correlation level (absolute value): low correlations, 0 to 0.1 (plain text), 0.1 (inclusive) to 0.3 (italic); moderate correlation, ≥0.3 to <0.5 (bold). HAQ-DI, lower score = better; DAS28, lower score = better; PASI, lower score = better; PsAQoL, lower score = better; DLQI, lower score = better; SF-36, higher score = better; EQ-5D VAS, higher score = better. BP, bodily pain; DAS28(CRP), Disease Activity Score – 28-joint count based on C-reactive protein; DLQI, Dermatology Life Quality Index; DMARD, disease-modifying antirheumatic drug; EQ-5D, EuroQoL-5 dimensions; GH, general health; HAQ-DI, Health Assessment Questionnaire – Disability Index; HRQoL, health-related quality of life; MCS, mental component summary; MH, mental health; PASI, Psoriasis Area and Severity Index; PCS, physical component summary; PsAQoL, Psoriatic Arthritis Quality of Life; PF, physical functioning; RE, role emotional; RP, role physical; SF, social functioning; SF-36, Short Form-36 items; VAS, visual analogue scale; VT, vitality; WPS, Work Productivity Survey.

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ISSN: 1478-6362

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