Table 1.

Characteristics of subjects in study.

Characteristics	C-PO, n = 63	C-GC, n = 18	p, C-GC vs C-PO^a	C-IV, n = 31	p, C-IV vs C-PO^a
Age, yrs, median (IQR; range)	11 (9–14; 2–16)	11 (8–15; 3–17)	0.64^b	12 (10–14; 5–17)	0.78^b
Male sex	45 (71)	11 (61)	0.40	17 (55)	0.11
Days of continuous joint symptoms at diagnosis	10 (5–30)	5 (3–28)	0.41^b	14 (7–28)	0.56^b
Continuous joint symptoms at presentation
≥ 6 weeks	9 (14)	2 (11)	0.60^c	3 (10)	0.31^c
Unknown	18 (29)	3 (17)		5 (16)
> 1 joint involved	6 (10)	4 (22)	0.22^c	5 (16)	0.50^c
Non-knee joint involved	6 (10)	2 (11)	0.99^c	2 (6)	0.99^c
Severe arthritis^d	22 (35)	8 (44)	0.46	11 (35)	0.96
Premature IAGC	1 (2)	1 (6)	0.40^c	0	0.99^c
HLA-B27–positive	3 (5)	0	0.42^c	1 (3)	0.56^c
HLA-B27 missing	48 (76)	12 (67)		27 (87)
Dose of first antibiotic course
Correct per guidelines^6,7	47 (75)	13 (72)	0.34^c	24 (77)	0.99^c
Dose unknown	10 (16)	5 (28)		5 (16)
Trajectory of disease activity at initiation of second-line treatment ^e
Improving	24 (38)	10 (56)	0.44^c	6 (19)	< 0.01
No change	21 (33)	5 (28)		5 (16)
Worsening	18 (29)	3 (17)		20 (65)
Marked clinical worsening ≤ 6 weeks after antibiotic initiation^f	9 (14)	0	0.20^c	12 (39)	0.01
Days of followup from diagnosis to final rheumatology clinic visit	263 (155–580)	102 (74–232)	< 0.01^b	264 (101–772)	0.62
Days of followup from diagnosis to final encounter in EHR	449 (200–1026)	331 (100–1060)	0.40	309 (101–1084)	0.35

Values are median (IQR) or n (%) unless otherwise specified.
↵a P value calculated from chi-square testing except where indicated.
↵b P value calculated from Wilcoxon rank-sum testing.
↵c P value calculated from Fisher’s exact test.
↵d Unexplained fever, severe pain, hospitalization for severe pain, or measured sedimentation rate ≥ 40 mm/h.
↵e Early improvement with subsequent worsening by the time of second-line treatment was characterized as worsening; early worsening with subsequent improvement by the time of second-line treatment was characterized as improving; no change indicated no change in clinical activity (i.e., extent of synovitis) from the time of first-line treatment to second-line treatment.
↵f Massive effusion, popliteal cyst rupture, or symptomatic joint recruitment after antibiotic initiation. C-GC: intraarticular glucocorticoid cohort; C-IV: intravenous antibiotics cohort; C-PO: oral antibiotics cohort; EHR: electronic health record; IAGC: intraarticular glucocorticoid; IQR: interquartile range.