Discriminant validity, responsiveness and reliability of the arthritis-specific Work Productivity Survey assessing workplace and household productivity within and outside the home in patients with axial spondyloarthritis, including nonradiographic axial spondyloarthritis and ankylosing spondylitis

Osterhaus, Jane T; Purcaru, Oana

doi:10.1186/ar4680

Table 4 Work Productivity Survey baseline scores by defined known-groups: workplace productivity (randomized set, observed cases) ^a

From: Discriminant validity, responsiveness and reliability of the arthritis-specific Work Productivity Survey assessing workplace and household productivity within and outside the home in patients with axial spondyloarthritis, including nonradiographic axial spondyloarthritis and ankylosing spondylitis

Instrument^b	Number of days of work missed over the previous month, mean		Number of days with productivity ≤50% at work over the previous month, mean		Rate of arthritis interference with work productivity over previous month, mean^c
	Worse	Better	Worse	Better	Worse	Better
BASDAI
axSpA (cutoff 5.20 and 7.50)	3.27^d	0.70	7.95^d	2.86	5.44^d	3.45
axSpA (cutoff 5.20 and 7.50)	n = 59	n = 57	n = 59	n = 57	n = 59	n = 57
AS (cutoff 5.20 and 7.30)	3.12^d	0.56	8.12^d	2.79	5.32^e	3.71
AS (cutoff 5.20 and 7.30)	n = 34	n = 34	n = 34	n = 34	n = 34	n = 34
nr-axSpA (cutoff 5.40 and 7.60)	3.19^f	0.79	9.63^f	3.85	5.74^d	3.26
nr-axSpA (cutoff 5.40 and 7.60)	n = 27	n = 28	n = 27	n = 28	n = 27	n = 28
BASFI
axSpA (cutoff 3.80 and 6.55)	4.02^d	0.68	7.34^f	4.22	5.79^d	3.55
axSpA (cutoff 3.80 and 6.55)	n = 56	n = 56	n = 56	n = 56	n = 56	n = 56
AS (cutoff 4.30 and 6.80)	3.09^e	0.87	5.47	2.73	5.31^d	3.40
AS (cutoff 4.30 and 6.80)	n = 32	n = 30	n = 32	n = 30	n = 32	n = 30
nr-axSpA (cutoff 3.20 and 6.40)	6.04^d	0.44	8.81	5.25	6.52^#	3.63
nr-axSpA (cutoff 3.20 and 6.40)	n = 27	n = 25	n = 27	n = 25	n = 27	n = 25
Total Spine Pain
axSpA (cutoff 6 and 8)	2.97^e	1.10	7.01^d	2.99	5.57^d	3.75
axSpA (cutoff 6 and 8)	n = 88	n = 82	n = 88	n = 82	n = 88	n = 82
AS (cutoff 6 and 8)	2.87^d	0.52	6.40^e	2.50	5.17^e	3.90
AS (cutoff 6 and 8)	n = 47	n = 42	n = 47	n = 42	n = 47	n = 42
nr-axSpA (cutoff 6 and 8)	3.07	1.70	7.71^e	3.51	6.02^d	3.59
nr-axSpA (cutoff 6 and 8)	n = 41	n = 40	n = 41	n = 40	n = 41	n = 40
SF-36 PCS
axSpA (cutoff 37.54 and 27.49)	2.85^e	0.76	6.13^f*	2.98	5.85^d	3.28
axSpA (cutoff 37.54 and 27.49)	n = 54	n = 55	n = 54	n = 55	n = 54	n = 55
AS (cutoff 37.44 and 27.93)	2.72^e	0.62	6.48	2.86	5.62^d	3.41
AS (cutoff 37.44 and 27.93)	n = 29	n = 29	n = 29	n = 29	n = 29	n = 29
nr-axSpA (cutoff 37.76 and 26.58)	3.84^f	0.92	6.52	3.12	6.64^d	3.12
nr-axSpA (cutoff 37.76 and 26.58)	n = 25	n = 26	n = 25	n = 26	n = 25	n = 26
SF-36 MCS
axSpA (cutoff 49.84 and 32.24)	4.78^d	0.81	8.18^e	3.54	5.58^e	3.93
axSpA (cutoff 49.84 and 32.24)	n = 55	n = 80	n = 55	n = 80	n = 55	n = 80
AS (cutoff 52.73 and 32.87)	3.86^e	0.89	7.00^f	3.00	5.07	4.18
AS (cutoff 52.73 and 32.87)	n = 29	n = 28	n = 29	n = 28	n = 29	n = 28
nr-axSpA (cutoff 46.98 and 30.79)	5.65^d	0.69	8.58^e	3.23	6.08^e	3.50
nr-axSpA (cutoff 46.98 and 30.79)	n = 26	n = 26	n = 26	n = 26	n = 26	n = 26
ASQoL
axSpA (cutoff 8.50 and 15.00)	4.40^d	0.62	8.00^d	3.35	6.26^d	2.98
axSpA (cutoff 8.50 and 15.00)	n = 58	n = 90	n = 58	n = 90	n = 58	n = 90
AS (cutoff 8.00 and 14.91)	3.77^d	0.42	7.53	3.61	5.73^d	3.03
AS (cutoff 8.00 and 14.91)	n = 30	n = 31	n = 30	n = 31	n = 30	n = 31
nr-axSpA (cutoff 9.00 and 15.00)	5.07^d	0.77	8.50^e	3.33	6.82^d	3.00
	n = 28	n = 30	n = 28	n = 30	n = 28	n = 30

^aASQoL: Ankylosing spondylitis quality of life; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; BASFI: Bath Ankylosing Spondylitis Functional Index; MCS: Mental Components Summary; PCS: Physical Components Summary; SF-36: Short form 36 items. ^bCutoff points represent the first and third quartiles of baseline scores: “Worse” state is defined for each individual measure as BASDAI score at or above the third quartile; BASFI score at or above the third quartile; Total Spine Pain score at or above the third quartile; ASQoL at or above the third quartile; SF-36 MCS at or below the first quartile; SF-36 PCS at or below the first quartile; “Better” state defined for each individual measure as BASDAI score at or below the first quartile; BASFI score at or below the first quartile; Total Spine Pain score at or below the first quartile; ASQoL score at or below the first quartile; SF-36 MCS, PCS at or above the third quartile; ^cWPS Q4 is scored on a 0 to 10 scale, where 0 = no interference and 10 = complete interference. ^dP ≤ 0.001; ^eP ≤ 0.01; ^fP ≤ 0.05; nonparametric bootstrap-t method with a variance stabilizing transformation, 10,000 replications.

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