Table 1

Sensitivity, specificity, and positive likelihood ratios (LRs) of clinical and laboratory SpA features in patients with ankylosing spondylitis (AS), controls with back pain, patients with any spondyloarthritis, or any controls. Listing of references according to the year of publication

	Sens. (%)	Spec. (%)	Positive LR	Group of patients and size of study group				Ref.
	Sens. (%)	Spec. (%)	Positive LR	AS (n)	Back pain controls (n)	All SpA (n)	Controls (n)*	Ref.
Figures in bold indicate the sensitivities, specificities, and positive LRs taken in our calculations.
Controls were in general patients with musculoskeletal diseases other than SpA; †apparently healthy sportsmen who had had an episode of back pain; ‡data on control patients were not available. Thus, the prevalence in the general population was assumed; §data from a German observational study on SpA (AS n = 138, unpublished); ¶sensitivity of HLA-B27 refers to SpA with axial involvement—that is, with inflammatory back pain; *MRI denotes magnetic resonance imaging.
Inflammatory back pain	95	76	4.0	42	21			22
	38	100	~	21			83	10
	65	79	3.1	27	422			25
	–	75†					774	24
	71	80	3.6	101	112			21
	75	76	3.1
Alternating buttock pain	20	97	6.6			403	674	14
	39	98	19.5			124	1964	16
	20	89	1.8			104	75	27
	43	95	9.6			218	1242	28
	43	100	~	44	29			30
	32	97	10.4			105	163	31
	37	88	3.7	101	112			21
	40	90	4.0
Heel pain (enthesitis)	16	90	1.6	70	32			34
	37	89	3.4			403	674	14
	25	90	2.5			104	75	27
	52	92	6.5			124	1964	16
	47	94	7.8			218	1242	28
	50	96	12.5	44	29			30
	52	93	7.4			105	163	31
	37	89	3.4
Peripheral arthritis	41	94	6.8	70	32			34
	40	90	4.0			403	674	14
	44	95	8.8			124	1964	16
	42	91	4.7			218	1242	28
	62	100	~	44	29			30
	26	98	13			105	163	31
	40	90	4.0
Dactylitis	18	96	4.5			403	674	14
	27	99	27			124	1964	16
	24	96	6			218	1242	28
	12	98	6			105	163	31
	18	96	4.5
Anterior uveitis	10	100	~	70	32			34
	19	–		42	12			12
	22	97	7.3			403	674	14
	14	99	14			124	1964	16
	13	99	13			218	1242	28
	4	100	~			105	163	31
	21	–		676				29
	22	97	7.3
Psoriasis	17	–		807				39
	1.2	–		676				29
	10	96‡	2.5					29
Inflammatory bowel disease	7	–		828				39
	1.7	–		676				29
	4	99‡	4
Positive family history for AS, reactive arthritis, IBD, psoriasis, anterior uveitis	7	100	~	70	32			34
	31	93	4.4			104	75	27
	32	95	6.4			403	674	14
	36	97	12			218	1242	28
	20	100	~	44	29			30
	15	99	15			105	163	31
	10	–		676				29
	32	95	6.4
Response to NSAIDs	77	85	5.1	69	769			16
	71	75	2.8			218	1242	28
	61	80	3.1			105	163	31
	64	–		676				29
	77	85	5.1
Raised acute phase reactants (CRP)	49	100	~	70	32			34
	69	67	3	42	12			12
	39	–		443				35
	38	–		149				36
	75	–		70				7
	51	75	2	101	112			21
	56§	–
	50	80	2.5
HLA-B27	96	96	24	40			906	37
	88	92	11	75			75	38
	83	95	16.6	70	32			34
	88	–		42	12			12
	–	91					1871	3
	89	94	14.8	101	112			21
	90¶	90	9.0
MRI**	93	100	~	25	12	15		40
	54	83	3.1		12	24		41
	83	93	11.8	36	53	36		42
	94	100	~		20	17		43
	90	–				41		44
	90	90	9.0