Table 2.

Validation studies of IFN gene signature as a potential biomarker for disease activity assessment in SLE

Study	Number of cases	Findings	Matching or adjustments	Controls for treatment effect	Validated disease-activity measures used	Study design	Included patients with a wide range of DAS?
Baechler et al. (2003)31	48	Expression levels of IFN-induced genes correlated with severe SLE manifestations	None	None	None	Cross-sectional	No
Bennett et al. (2003)32	30	Expression levels of IFN-induced genes correlated with disease activity	None	Controlled for corticosteroid treatment	SLEDAI	Cross-sectional	Yes
Kirou et al. (2005)33	77	Expression levels of IFN-induced genes correlated with disease activity	Matched for age and gender	Controlled for hydroxychloroquine treatment	SLEDAI-2K	Cross-sectional Longitudinal follow-up in 1 patient	Yes
Feng et al. (2006)34	48	Expression levels of IFN-induced genes correlated with disease activity	None	None	SELENA-SLEDAI	Cross-sectional	Yes
Nikpour et al. (2007)35	269	Expression levels of IFN-induced genes correlated with disease activity	Adjusted for age	Controlled for prednisone treatment	SLEDAI-2K	Cross-sectional	Yes
Landolt-Marticorena et al. (2008)36	94	Expression levels of IFN-induced genes linked to disease flares Expression levels of IFN-induced genes correlation poorly with longitudinal changes in disease activity	None	Controlled for use immunosuppressive agents	SLEDAI-2K	Cross-sectional Longitudinal (1 year) for 27 patients	Yes

Abbreviations: DAS, disease activity scores; IFN, interferon; SELENA-SLEDAI, Safety of Estrogens in Lupus Erythematosus: National Assessment (SELENA)-Systemic Lupus Erythematosus (SLE) Disease Activity Index (SLEDAI); SLEDAI-2K, SLEDAI 2000.