Table 3 Sensitivity and specificity of the experts’ criteria for inflammatory back pain (IBP) in comparison with other IBP criteria in the workshop patients (n = 20 patients) and in the Assessment of Spondyloarthritis International Society (ASAS) validation study (n = 648 patients) against global expert judgement on presence or absence of IBP

	ASAS workshop* (n = 20 patients)		ASAS validation study† (n = 648 patients)
	Sensitivity (%)	Specificity (%)	Sensitivity (%)	Specificity (%)
IBP according to experts:
At least 3/5 present	91.8	56.3	95.1	47.5
At least 4/5 present	77.0	91.7	79.6	72.4
All 5/5 present	41.0	100	38.6	91.9
Calin criteria:‡
At least 4/5 present	82.0	73.0	89.9	52.5
Berlin criteria:¶
At least 2/4 present	83.6	62.5	70.0	81.4

Note that sensitivity and specificity refer to presence of IBP, not to diagnosis.
*ASAS Workshop patients: in total, 109 judgements on IBP were made by 13 experts in 20 patients; †ASAS validation study: in total 648 judgements on IBP in 648 patients from 25 centres worldwide were made by the local rheumatologist; ‡Calin criteria refers to IBP criteria by Calin et al,4 which are fulfilled if at least 4 of the following 5 items are present: (1) age at onset <40 years; (2) back pain >3 months; (3) insidious onset; (4) associated with morning stiffness; (5) improvement with exercise; ¶Berlin criteria refers to IBP criteria by Rudwaleit et al,6 which are fulfilled if at least 2 of the following 4 items are present: (1) morning stiffness >30 min; (2) improvement with exercise but not with rest; (3) awakening in the second half of the night because of back pain; (4) alternating buttock pain.