Baseline serum MMP-3 levels in patients with Rheumatoid Arthritis are still independently predictive of radiographic progression in a longitudinal observational cohort at 8 years follow up

Table 1 Comparison of baseline demographic characteristics, clinical and biomarker measures in radiographic progressor groups at 8.2 years

	Low Progressors*	High Progressors*	Comparison		SRC
Cohort characteristics	(n= 29)	(n= 29)	z	P ^$	rho	P
Demographic
Female, no. (%)	22 (76%)	15 (52%)	3.66	0.100^†	-	NA
Age, mean ± SD, years	52 ± 10	55 ± 12	0.97	0.334^‡	-	NA
Disease duration, days	260 (169, 412)	242 (146, 384)	-0.59	0.555	-	NA
DAS28	5.1 (4.0, 6.1)	6.2 (4.8, 6.8)	1.73	0.083	-	NA
HAQ	1.3 (0.9, 2.0)	1.5 (1.0, 2.3)	0.90	0.370	-	NA
No. DMARDs^φ	2 (1, 2)	2 (2, 3)	1.81	0.070	-	NA
MTX, no. (%)^φ	8 (28)	21 (72)	11.66	0.001^†	-	NA
Traditional measures
Total SHS	3 (0, 8)	16 (6, 28)	4.09	< 0.001	0.51	< 0.001
ESR, mm/hour	19 (11, 39)	34 (20, 50)	2.33	0.020	0.35	0.008
CRP mg/L	8 (5, 20)	34 (15, 65)	3.42	< 0.001	0.46	< 0.001
RF positive, no. (%)	19 (66%)	26 (90%)	4.86	0.056^†	0.47	< 0.001
Anti-CCP +ve, no. (%)^φ	14 (48%)	26 (90%)	11.60	0.001^†	0.23	0.077
SJC	6 (2, 12)	10 (5, 15)	1.80	0.072	0.19	0.145
TJC	14 (5, 18)	15 (7, 18)	0.47	0.640	0.06	0.675
CGA on VAS, mm	24 (10, 57)	54 (38, 68)	2.48	0.013	0.34	0.010
PGA on VAS, mm	39 (27, 48)	47 (24, 65)	0.53	0.600	0.10	0.447
Biomarkers
MMP-3, ng/mL	51 (32, 86)	137 (86, 359)	3.83	< 0.001	0.46	< 0.001
CTX-II, μg/mmol	0.14 (0.08, 0.25)	0.36 (0.19, 0.57)	3.40	< 0.001	0.40	0.003
COMP, U/L	10 (8, 11)	13 (11, 16)	3.27	0.001	0.39	0.003
TIMP-1, ng/mL	647 (466, 719)	817 (669, 902)	2.34	0.019	0.29	0.029

*Except where indicated otherwise, values are median (25^th and 75^th percentiles). ^$Determined by Mann Whitney U test unless indicated otherwise. ^†Determined by Fisher's two-sided exact test. ^‡Determined by Student's t test. ^φ Value taken at 8.2-year follow-up visit.
Anti-CCP, anti-cyclic citrullinated peptide; CGA, clinician's global assessment; COMP, cartilage oligomeric matrix protein; CRP, C-reactive protein; CTX-II, C-telopeptide of type II collagen; DAS, disease activity score; DMARD, disease-modifying anti-rheumatic drug; ESR, erythrocyte sedimentation rate; HAQ, health assessment questionnaire; MMP-3, matrix metalloproteinase-3; MTX, methotrexate; NA, not applicable; NS, not significant; PGA, patient's global assessment; RF, rheumatoid factor; SD, standard deviation; SHS, van der Heijde modified Sharp score; SJC, swollen joint count; SRC, Spearman's rank correlation; TIMP-1, tissue inhibitor of metalloproteinase 1; TJC, tender joint count; VAS, visual analogue score.

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