Table 3

Multivariable logistic regression analyses with synovitis on joint examination as outcome

	Model 1		Model 2
	Derivation		Derivation			Validation
		OR (95% CI)		OR (95% CI)	B	OR (95% CI)
Male		1.7 (1.1 to 2.5)		1.7 (1.1 to 2.5)	0.517	1.7 (1.1 to 2.4)
Age (years)	<40	(ref)	0–59.9	(ref)	(ref)	(ref)
	40–59.9	1.5 (0.96 to 2.5)	≥60	2.1 (1.4 to 3.1)	0.750	2.1 (1.5 to 3.0)
	≥60	2.9 (1.7 to 4.8)
Symptom duration (weeks)	<6	3.8 (2.3 to 6.4)	<6	3.6 (2.2 to 6.0)	1.279	3.4 (2.0 to 5.7)
Symptom duration (weeks)	6–11	1.7 (0.92 to 3.1)	6–51.9	2.2 (1.4 to 3.6)	0.797	1.9 (1.2 to 3.0)
	12–51.9	2.9 (1.7 to 5.0)	≥52	(ref)	(ref)	(ref)
	≥52	(ref)
Acute onset of symptoms*		1.0 (0.67 to 1.5)		0.99 (0.66 to 1.5)	−0.015	1.0 (0.70 to 1.5)
Morning stiffness (minutes)	>60	1.6 (0.88 to 2.9)	>60	1.6 (0.91 to 2.9)	0.485	1.2 (0.62 to 2.3)
Number of painful joints	0	(ref)	0	(ref)	(ref)	(ref)
Number of painful joints	1–3	9.3 (1.1 to 78.2)	1–3	10.0 (1.2 to 83.4)	2.300	7.9 (0.91 to 68.6)
	4–10	4.5 (0.53 to 37.6)	≥4	4.5 (0.54 to 37.1)	1.497	5.2 (0.61 to 45.1)
	≥11	3.3 (0.39 to 28.4)
Number of patient-reported swollen joints	0	(ref)	0	(ref)	(ref)	(ref)
	1–3	3.2 (1.6 to 6.4)	≥1	3.5 (1.9 to 6.6)	1.253	3.7 (1.9 to 7.0)
	4–10	3.4 (1.7 to 7.0)
	≥11	4.3 (1.9 to 10.0)
Difficulty with making a fist		1.6 (0.97 to 2.5)		1.6 (0.99 to 2.6)	0.467	1.4 (0.91 to 2.2)
Intercept		−4.8			−4.6	−4.6
AUC		0.76 (0.71 to 0.80)		0.75 (0.70 to 7.79)		0.72 (0.68 to 0.77)

Model 1 includes categories of clinically applicable cut-offs; if within variables, several categories had similar regression coefficients, categories were pooled (model 2).
*Patients were asked to define onset of symptoms; either acute onset of symptoms or gradual onset of symptoms, see online supplementary appendix S1. Variables with p values <0.05 in univariable analysis in the derivation set were entered in multivariable regression analyses.
AUC, area under the receiver operating characteristic curve; B, beta.