Immune indicators and depression in adolescents: Associations with monocytes, lymphocytes, and direct bilirubin

Table 1 Comparison of sociodemographic and laboratory variables between healthy controls and patients with depression

Variables	Group		Test
	DEP (n = 145)	HC (n = 163)
Sex, n (%)			χ2 = 13.62, P < 0.001, OR = 2.51 (95%CI: 1.56- 4.09)
Male	38 (26.21)	77 (47.24)
Female	107 (73.79)	86 (52.76)
Age (year)			Z = 9.43; P < 0.001
Min/Max	12.0/24.0	13.0/26.0
Median (P25, P75)	17 (16, 20)	22 (21, 23)
Monocyte count (× 109/L)			Z = 3.43; P < 0.001
Min/Max	0.2/2.0	0.2/1.7
Median (P25, P75)	0.52 (0.43, 0.61)	0.45 (0.37, 0.55)
Lymphocyte count (× 109/L)			t = 2.29; P < 0.05
Min/Max	1.1/6.8	1.0/4.8
Mean (SD)	2.60 ± 0.89	2.38 ± 0.66
Direct bilirubin concentration (μmol/L)			Z = 4.72; P < 0.001
Min/Max	0.4/11.4	0.9/10.0
Median (P25, P75)	3.30 (2.30, 4.65)	2.41 (1.90, 3.26)

DEP: Depression; HC: Healthy control; Min: Minimum; Max: Maximum.

Table 2 One-way analysis of variance analysis of immune markers in different degrees of depression

Variables	Mild depression (n = 20), median (P25, P75)/mean (SD)	Moderate depression (n = 37), median (P25, P75)/mean (SD)	Severe depression (n = 88), median (P25, P75)/mean (SD)	F/χ2	P value
Monocyte count (× 109/L)	0.445 (0.35, 0.52)	0.53 (0.43, 0.56)	0.54 (0.438, 0.68)	8.52	0.014a
Lymphocyte count (× 109/L)	2.24 ± 0.59	2.58 ± 0.81	2.69 ± 0.97	2.27	0.107
Direct bilirubin concentration (μmol/L)	3.72 ± 1.69	3.90 ± 2.00	3.59 ± 2.09	0.64	0.530

^aP < 0.05.

Table 3 Multivariable logistic regression

Variable	Coefficient	OR (95%CI)	SE	Z	P value
Intercept	6.52	680.18 (60.10-8666.00)	1.27	5.14	0.000a
Monocyte count	1.17	3.22 (0.49-24.90)	1.00	1.17	0.243
Lymphocyte count	-0.03	0.97 (0.60-1.57)	0.24	-0.11	0.911
Direct bilirubin concentration	0.40	1.49 (1.23-1.83)	0.10	3.91	0.000a
Sex (male)	-1.09	0.34 (0.18-0.61)	0.31	-3.50	0.000a
Age	-0.41	0.67 (0.60-0.73)	0.05	-7.93	0.000a

^aP < 0.001.