	N	%	N	%	P value
Female	236	71.5	98	72.6	0.81
Race					0.81
White or Caucasian	293	88.8	117	86.7
Black or African American	21	6.4	9	6.7
Other	12	3.6	7	5.2
Unknown	4	1.2	2	1.5
JIA subtype					0.03
Poly RF−	118	35.8	61	45.2
Poly RF+	26	7.9	15	11.1
Oligo	105	31.8	26	19.3
Other	81	24.5	33	24.4
Insurance					0.83
Public	82	24.8	33	24.4
Private	222	67.3	89	65.9
Other	26	7.9	13	9.6
Morning stiffness					0.002
None	65	19.7	16	11.9
15 min	35	10.6	12	8.9
>15 min	116	35.2	73	54.1
Unknown	114	34.5	34	25.2
Uveitis ever					0.96
No	143	43.3	57	42.2
Yes	10	3.0	4	3.0
Unknown	177	53.6	74	54.8
Elevated C reactive protein	43	13.0	38	28.1	<0.0001
Rheumatoid factor—positive	18	5.5	18	13.3	0.004
Antinuclear antibodies—positive	33	10.0	21	15.6	0.09
HLA-B27—present	13	3.9	10	7.4	0.12
Previous treatment with NSAID	252	76.4	79	58.5	0.0001
Previous treatment with prednisone	20	6.1	13	9.6	0.17

*P values of χ² for categorical variables and Student t-test for continuous variables.
HLA-B27, Human leukocyte antigen B27; JIA, juvenile idiopathic arthritis; NSAID, non-steroidal anti-inflammatory drug; RF, rheumatoid factor.