Table 2. Regression models for major depression disorder chronicity, possible predictive models of discrimination between patients in first depressive episode (MD: n = 30) and patients with treatment-resistant depression (TRD: n = 28).

Models	AICc	ΔAICc	Β	z-score	p-value
I
CAR	32.57	0	< 0.001	2.70	0.006
SC			< 0.001	4.46	< 0.001
mBDNF			< 0.001	2.31	0.02
PSQI			< 0.001	2.06	0.03
II
CAR	34.37	1.80	< 0.001	2.70	0.006
SC			< 0.001	4.46	< 0.001
mBDNF			< 0.001	2.31	0.02
III
CAR	35.31	2.74	< 0.001	2.70	0.006
SC			< 0.001	4.46	< 0.001
PSQI			< 0.001	2.06	0.03
IV
SC	37.73	5.16	< 0.001	4.46	< 0.001
mBDNF			< 0.001	2.31	0.02
PSQI			< 0.001	2.06	0.03
V
CAR	38.06	5.49	< 0.001	2.70	0.006
SC			< 0.001	4.46	< 0.001
VI
SC	39.94	7.37	< 0.001	4.46	< 0.001
PSQI			< 0.001	2.06	0.03
VII
SC	42.39	9.82	< 0.001	4.46	< 0.001
mBDNF			< 0.001	2.31	0.02
VIII
SC	45.82	9.82	< 0.001	4.46	< 0.001
IX
CAR	49.39	16.82	< 0.001	2.70	0.006
mBDNF			< 0.001	2.31	0.02
PSQI			< 0.001	2.06	0.03
X
CAR	52.19	19.62	< 0.001	2.70	0.006
mBDNF			< 0.001	2.31	0.02

Bold result indicates the best regression model with the lowest AICc and ΔAICc< 2. All models showed in this table were statistically significant (p< 0.05) and controlled by age and sex, while 2 of them were ΔAICc< 2. CAR: cortisol awakening response; SC: total serum cortisol; mBDNF: mature brain-derived neurotrophic factor; PSQI: Pittsburgh sleep quality index.