Machine learning identification of thresholds to discriminate osteoarthritis and rheumatoid arthritis synovial inflammation

Table 1 Patient characteristics

Feature	OA N=147	RA N=60	p-value
Age, mean (SD)	65.2 (6.6)	64.0 (9.1)	0.32
Sex: female	90 (61.2%)	50 (83.3%)	0.002
BMI, median (IQR)	30.0 (27.1, 3)	28.1 (23.7, 33.2)	0.006
Race			0.95
White	117 (79.6%)	46 (76.7%)
Asian	8 (5.4%)	3 (5.0%)
Black	15 (10.2%)	6 (10.0%)
Other^*	4 (2.7%)	2 (3.3%)
Missing	3 (2.0%)	3 (5.0%)
History of cigarette use	55 (37.4%)	36 (60.0%)	0.003
ESR (mm/hr), median (IQR)	14 (6.5, 25.5)	14.5 (7.5, 25.5)	0.50
CRP, median (IQR)	0.16 (0.08, 0.36)	1.05 (0.0, 2.4)	<0.001
RF positive	1 (0.7%)	30 (50.0%)
Missing		3 (5.0%)
Anti-CCP interpretation
Negative	147 (100.0%)	12 (20.0%)
Positive: 1–3× ULN		13 (21.7%)
High positive: >3× ULN		34 (56.7%)
Missing		1 (1.7%)
DAS28-ESR, mean (SD)	n/a	3.9 (1.2)	n/a
DAS28-CRP, mean (SD)	n/a	3.8 (1.3)	n/a
Duration since diagnosis, median (IQR)	7.2 (3.2, 15.0)	12.1 (3.7, 19.4)	0.032
Duration since symptom onset, median (IQR)	10.6 (5.7, 19.6)	14.9 (4.7, 22.5)	0.34
Currently using NSAIDs	85 (57.8%)	32 (53.3%)
Missing		3 (5.0%)
Currently using oral steroids	2 (1.4%)	23 (38.3%)
Missing		1 (1.7%)
Currently using methotrexate		31 (51.7%)
Missing	147 (100.0%)	1 (1.7%)
Currently taking any other DMARD		17 (28.3%)
Missing	147 (100.0%)	2 (3.3%)
Currently taking a biologic		33 (55.0%)
Missing^a	147 (100.0%)	2 (3.3%)
Which biologic
Abatacept (Orencia)		4 (6.7%)
Adalimumab (Humira)		6 (10.0%)
Certolizumab (Cimzia)		1 (1.7%)
Etanercept (Enbrel)		15 (25.0%)
Infliximab (Remicade)		1 (1.7%)
Tocilizumab (Actemra)		3 (5.0%)
Tofacitinib (Xeljanz)		3 (5.0%)
Missing^a	147 (100.0%)	27 (45.0%)

Data represents N (%) unless stated otherwise. “Missing” lines indicate the number (and %) of patients for whom data is not available for a given feature. ^aData on biologic usage was not collected in OA patients. OA osteoarthritis, RA rheumatoid arthritis, SD standard deviation, IQR interquartile range, DAS28 Disease Activity Score-28, ESR erythrocyte sedimentation rate, mm/hr millimeters/hour, CRP C-reactive protein, RF rheumatoid factor, CCP cyclic citrullinated peptide, ULN upper limit of normal, NSAIDs non-steroidal anti-inflammatory drugs, DMARD disease-modifying antirheumatic drug. A chi-squared test was performed to assess statistically significant differences between RA and OA patients. Bold represents p < 0.05. ^*Other category of race includes American Indian, Alaskan Native, Native Hawaiian, Pacific Islander, and other race. Duration since diagnosis and duration since symptom onset represent number of years.

ISSN: 1478-6362