Table 2.

Results of multivariate GLM analyses with the six cytokine biomarkers [interleukin (IL)-1α, soluble interleukin 1 receptor antagonist (sIL-1RA), soluble interleukin 2 receptor (sIL-2R), soluble interleukin 6 receptor (sIL-6R), soluble tumor necrosis factor receptor 60 kDa / 80 kDa (sTNF-R1/2)] and thiobarbituric acid reactive substances (TBARS) as dependent variables and diagnostic groups, age, gender, marital status, and nicotine dependence as explanatory variables

Tests	Dependent variables	Explanatory variables	F	df	p
(1) Multivariate analysis in MDD patients	7 biomarkers	TRD vs non-TRD Age Sex TUD PC1 PC2	2.33 3.52 0.77 2.76 1.50 0.62	7/64	0.035 0.003 0.619 0.014 0.184 0.735
Between-subject effects	sIL-6R sTNF-R2 TBARS	TRD vs non-TRD TRD vs non-TRD TRD vs non-TRD	5.24 4.66 5.12	1/70	0.025 0.034 0.027
Between-subject effects	sTNF-R1 sTNF-R2	Age (+) Age (−)	7.78 8.86	1/70	0.007 0.004
Between-subject effects	IL-1α sIL-2R	TUD TUD	5.54 0.74	1/70	0.021 0.002
(2) Multivariate analysis in MDD patients and controls	7 biomarkers	TRD, non-TRD, HC Age Sex TUD PC1 PC2	3.31 2.01 1.04 2.71 1.38 0.88	14/208 7/103 7/103 7/103 7/103 7/103	< 0.001 0.061 0.406 0.013 0.224 0.523
Between-subject effects	sIL-1RA sIL-6R sTNF-R2 TBARS	TRD, non-TRD, HC TRD, non-TRD, HC TRD, non-TRD, HC TRD, non-TRD, HC	4.37 3.06 3.27 9.85	2/109	0.015 0.051 0.042 < 0.001

Results of two different multivariate GLM analyses (with tests for between-subject effects) considering the effects of diagnostic groups entered as (1) two groups, i.e., TRD versus non-TRD; or (2) three groups, i.e., TRD versus non-TRD versus healthy controls (HC)