Validation of the adjusted multi-biomarker disease activity score as a prognostic test for radiographic progression in rheumatoid arthritis: a combined analysis of multiple studies

Table 2 Univariable analyses of association of baseline measures with radiographic progression. Univariable linear regression was used to evaluate the association of baseline demographic and disease activity-related variables with degree of radiographic progression, treated as a continuous (ΔTSS) or categorical (ΔTSS > 5) variable. The four cohorts analyzed are OPERA, BRASS, Leiden, and SWEFOT. Results are in descending order of statistical significance

Variable	Leiden and SWEFOT cohorts combined					4 cohorts combined
	N^a	*∆TSS (continuous)*		*∆TSS > 5*		N^a	*∆TSS (continuous)*		*∆TSS > 5*
	N^a	Coefficient^b (95% CI)	p value	Odds ratio (95% CI)	p value	N^a	Coefficient^b (95% CI)	p value	Odds ratio (95% CI)	p value
Adjusted MBDA score	398	0.11 (0.067, 0.14)	1.9 × 10⁻⁸	1.05 (1.03, 1.07)	5.5 × 10⁻⁸	953	0.061 (0.044, 0.076)	2.5 × 10⁻¹³	1.05 (1.03, 1.06)	2.5 × 10^− 11
Seropositivity^c	299/ 397	2.23 (1.00, 3.46)	4.2 × 10⁻⁴	4.18 (1.89, 11.1)	1.7 × 10⁻⁴	719/952	1.47 (0.89, 2.06)	9.9 × 10⁻⁷	6.20 (2.90, 16.1)	7.0 × 10⁻⁸
ln(CRP + 1)	391	1.01 (0.37, 1.50)	6.6 × 10^− 4	1.45 (1.15, 1.93)	0.0018	946	0.58 (0.33, 0.83)	4.7 × 10⁻⁶	1.57 (1.29, 1.91)	6.8 × 10⁻⁶
Baseline TSS	398	0.043 (0.017, 0.062)	2.1 × 10⁻⁴	1.01 (1.00, 1.02)	0.0023	953	0.0074 (0.0028, 0.012)	0.0018	1.01 (1.00, 1.01)	0.0072
DAS28-CRP	391	0.53 (− 0.0075, 0.91)	0.055	1.21 (1.01, 1.56)	0.035	927	0.31 (0.11, 0.50)	0.0026	1.24 (1.05, 1.46)	0.0096
Swollen Joint Count	398	0.082 (− 0.017, 0.17)	0.12	1.03 (0.99, 1.07)	0.17	953	0.062 (0.02-0.10)	0.004	1.04 (1.00, 1.07)	0.05
Male sex	120/ 398	− 0.61 (− 1.78, 0.57)	0.31	0.89 (0.50, 1.55)	0.69	243/953	− 0.45 (− 1.04, 0.14)	0.14	0.78 (0.47, 1.26)	0.32
Age	398	− 0.014 (− 0.053, 0.026)	0.50	0.99 (0.97, 1.01)	0.36	953	− 0.0043 (− 0.024, 0.015)	0.66	1.00 (0.98, 1.01)	0.67
CDAI	233	0.016 (− 0.057, 0.09)	0.66	1.00 (0.97, 1.03)	0.81	766	0.014 (− 0.0053, 0.034)	0.15	1.01 (0.99, 1.02)	0.47

Abbreviations: CI confidence interval, CRP C-reactive protein, DAS28-CRP Disease Activity Score using 28-joint count and CRP, MBDA multi-biomarker disease activity, ln natural logarithm, RF rheumatoid factor, TSS van der Heijde-modified total Sharp score
^aPatients within the total group that had suitable radiographic data and for whom baseline data were available for the indicated variable. Ratios indicate the number of patients in the indicated category and the total number with data available for assessing that variable
^bCoefficients for continuous variables (i.e., all variables except seropositivity, male, and smoking status) represent slope of the linear regression line, expressed as units of ΔTSS per one-unit change in the indicated variable
^cSeropositivity was defined as having tested positive for RF, anti-cyclic citrullinated peptide antibodies or both

ISSN: 1478-6362