Table 3

Results for outcome disease activity*

Baseline predictors (within 6 months after diagnosis)	Number of studies
Baseline predictors (within 6 months after diagnosis)	−	<†	NS	>†	+	References
Demographics
Gender: female		1/1	4			24^, 36^, 37^, 39–41
Higher age at onset			5	1/0	1	24^, 36^, 37^, 39–42
Higher age at diagnosis		1/1				36^, 38
Longer time from onset to diagnosis	2					36^, 40
Family history of AS in first degree relative	1					37
JIA category‡			1			39
Oligoarticular persistent				0/1		42
Oligoarticular extended		0/1		0/1		24^, 42
Systemic	1	0/1		1/1		24^, 36^, 41^, 42
Poly RF−	1	0/2	1			24^, 36^, 40^, 41
Poly RF+		0/3	2			24^, 36^, 38^, 40^, 41
Psoriatic			1			36
ERA		0/1	1			34^, 36
Undifferentiated
Disease activity
Higher active joint count	1	1/0	1			36^, 41^, 42
Higher limited joint count			2			36^, 42
Higher PGA		1/0				36
Higher parent/patient GA		1/0				36
Higher pain VAS		1/0				36
Higher CHAQ score		1/0				36
Higher JAQQ score	1					36
Hip involvement	1					34
Ankle involvement	1					37
Sacroiliitis present	1					34
Enthesitis present	1					34
Uveitis		1/0				41
Laboratory
ANA positive		1/0	3			24^, 36^, 39^, 41
RF positive	1	1/0				36^, 41
Higher ESR			2			36^, 42
Higher number of months with elevated ESR (in first 6 months)	1					41
Higher CRP			2			36^, 42
α₂- or γ-globulins			1			42
Genetics
HLA-B27 positive	1	1/1				34^, 41^, 42
HLA-DRB1*08	2					37^, 41
RANTES −28G allele		0/1				35
RANTES −403A allele			1			35
Imaging
Erosions or joint space narrowing on images		0/1				38

*Values are the number of studies that found that particular result for the respective predictors.
†The first number in this column refers to the number of studies that performed a multivariate analysis disconfirming the univariate finding (studies in which the multivariate analysis confirmed the univariate finding, are shown in the columns labelled − and +, respectively). The second number in this column refers to the number of studies that did not perform a multivariate analysis.
‡In studies that evaluated onset categories oligoarticular, polyarticular and systemic, results have been duplicated for oligoarthritis persistent and extended, and polyarthritis RF-positive and RF-negative, respectively.
−, lower chance of favourable outcome in multivariate analysis (p≤0.05); <, lower chance of favourable outcome in univariate analysis (p≤0.05); NS, not significant (p>0.05); S, significant in univariate analysis. Direction of the effect not shown (p≤0.05); >, higher chance of favourable outcome in univariate analysis (p≤0.05); +, higher chance of favourable outcome in multivariate analysis (p≤0.05). ANA, antinuclear antibodies; AS, ankylosing spondylitis; CHAQ, childhood health assessment questionnaire; CRP, C-reactive protein; ERA, enthesitis-related arthritis; ESR, erythrocyte sedimentation rate; GA, global assessment; HLA, human leucocyte antigen; IFN, interferon; IL, interleukin; JAQQ, juvenile arthritis quality of life questionnaire; JIA, juvenile idiopathic arthritis; PIP, proximal interphalangeal joint; PGA, physician's global assessment; RF, rheumatoid factor; TGF, transforming growth factor; TNF, tumour necrosis factor; VAS, visual analogue scale.