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Table 3 WPS-RA baseline responses by HAQ-DI and SF-36: work productivity of employed subjects in the modified intent-to-treat population

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

Instrumenta Number of days of work missed over the previous month, mean (SD) Number of days with productivity ≤ 50% at work over the previous month, mean (SD) Rate of arthritis interference with WPb over the previous month, mean (SD)
  Worst Best Worst Best Worst Best
HAQ-DI
(cutoff 0.5 and 1.5)
3.0 (7.19) 1.1c (3.45) 6.8 (8.96) 3.4c (6.88) 4.8 (2.77) 4.4d (2.67)
  n = 46 n = 35 n = 46 n = 35 n = 46 n = 35
SF-36 PCS
(cutoff 21.76 and 35.26)
2.9 (6.96) 1.3e (4.50) 8.7 (10.02) 2.2c (4.60) 6.0 (2.13) 3.5c (2.16)
  n = 21 n = 20 n = 21 n = 20 n = 21 n = 20
SF-36 MCS
(cutoff 38.36 and 54.67)
4.1 (8.07) 0.7c (1.59) 10.6 (11.07) 4.0c (7.83) 5.2 (2.89) 4.1c (2.47)
  n = 20 n = 21 n = 20 n = 21 n = 20 n = 21
  1. 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, dP value < 0.01, eP value ≤ 0.05 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.