Table 2

Development of subset assessment of candidate improvement criteria for anti-TNFα agents in ankylosing spondylitis on the basis of the six domains of pain, patient global, function, inflammation, spinal mobility, and C reactive protein

Criterion	Improvement definition	Infliximab trial (n = 69)				Combined dataset of etanercept and infliximab trials (n = 69) (χ²)
Criterion	Improvement definition	Per cent improving in placebo group (n = 35)	Per cent improving in infliximab group (n = 34)	χ²	95% CI of the χ² value
Columns 3–7: infliximab trial, week 12. Last column: data from the combined dataset at week 6; to be comparable, n = 69 from n = 99 at random. The criteria that performed best are shown in bold.
*Candidate criteria with χ² values that are not statistically significant below reference criterion 1.
†Placebo response significantly above 10%.
CI, confidence interval.
Relative improvement
1	⩾20% change in any five of six domains	2.86	67.65	31.91*	18.02 to 46.94	27.43
2	⩾30% change in any five of six	2.86	50.00	19.88	9.05 to 32.53	15.89
3	⩾40% change in any five of six	2.86	44.12	16.48	6.99 to 27.81	15.95
4	⩾30% change in any four of six	5.71	64.71	26.46*	13.86 to 41.11	20.44
5	⩾40% change in any four of six	5.71	61.76	24.38*	11.52 to 39.20	23.09
6	⩾50% change in any four of six	5.71	52.94	18.69	7.93 to 32.38	19.48
7	⩾30% change in any three of six	22.86†	73.53	17.75	4.96 to 34.02	25.88
8	⩾40% change in any three of six	8.57	67.65	25.63*	12.72 to 40.36	22.35
9	⩾50% change in any three of six	8.57	61.76	21.51*	9.51 to 36.91	21.95

Relative and absolute improvement
10	⩾20%/10 units change in any five of six domains	2.86	64.71	29.69*	16.26 to 44.25	27.72
11	⩾30%/10 units change in any five of six	2.86	47.06	18.15	7.90 to 30.34	15.89
12	⩾40%/20 units change in any five of six	0.0	38.24	16.49	8.53 to 26.67	15.78
13	⩾30%/10 units change in any four of six	5.71	64.71	26.46*	13.86 to 41.11	20.84
14	⩾40%/20 units change in any three of six	8.57	67.65	25.63*	12.72 to 40.36	22.64
15	⩾50%/20 units change in any three of six	8.57	58.82	19.60*	8.32 to 33.75	21.95
16	⩾60%/30 units change in any three of six	0.0	47.06	21.44*	11.91 to 32.53	17.04

Relative improvement including pain
17	⩾20% change in any five of six domains, including pain	2.86	67.65	31.91*	18.02 to 46.94	27.43
18	⩾40% change in any four of six, including pain	5.71	58.82	22.40*	10.14 to 36.96	23.09

Combinations in relative improvement
19	⩾40% in four of six domains or ⩾30% in five of six	5.71	61.76	24.38*	11.52 to 39.20	20.69
20	⩾50% in four of six or ⩾30% in five of six	5.71	58.82	22.40*	10.14 to 36.71	20.69