Cytokines and depression in cancer patients and caregivers

Figures & data

Table 1 Characteristics of the sample population

Characteristics	Cancer patients (n=61)	Caregivers (n=26)	Healthy controls (n=38)	p-value
Demographics
Sex, female (%)	35 (57)	17 (65)	21 (55)	0.70
Mean income, CAD (SD)	$88.5K ($42K)	$99.8K ($48K)	N/A	0.29
Mean age, years (SD)	55.5 (11.6)	56.3 (12.0)	43.5 (11.7)	0.36
Ethnicity, n (%)
Caucasian	49 (80)	21 (81)	24 (63)	0.081
Asian	5 (8)	5 (19)	9 (24)
Other	7 (12)	0	5 (13)
Biobehavioral variables
Mean BMI (SD)	25.2 (5.8)	N/A	N/A
CCI (SD)*	5.0 (2.2)	2.3 (0.6)	2.0 (0.2)	<0.001
Smokers (%)	8 (13.1)	3 (11.5)	6 (15.8)	0.94
Alcohol (SD) (drinks/week)	2.71 (5.47)	3.56 (5.13)	2.01 (2.66)	0.62
Caffeine (SD) (drinks/week)	21.5 (22.5)	20.7 (14.1)	15.9 (12.5)	0.59
Exercise habits (SD)**	1.77 (0.75)	1.96 (0.81)	2.41 (0.84)	0.009

Notes:

* CCI calculated without age.

** Mean (SD) exercise habits rated as: 1, sedentary; 2, mild regular; 3, occasional vigorous; 4, regular vigorous.

Abbreviations: BMI, body mass index; CCI, Charlson Comorbidity Index; N/A, not available.

Table 2 Ham-D scores across the sample population

Sample population	Mean Ham-D total (SD)		Mean Ham-Dep (SD)		Mean Ham-Som (SD)
Cancer patients (n=61)		10.1 (7.4)		3.2 (3.5)		2.3 (2.1)
Patients with MD (n=19)	22.7 (7.1)		6.5 (3.4)		3.5 (2.2)
Patients without MD (n=42)	7.2 (5.4)		1.7 (2.3)		1.7 (1.8)
Caregivers (n=26)		7.3 (7.4)		2.7 (3.4)		1.2 (1.4)
Caregivers with MD (n=3)	16.6 (5.5)		10 (2.0)		2.7 (1.5)
Caregivers without MD (n=23)	5.3 (4.9)		1.8 (2.2)		1.0 (1.3)
Cancer vs caregiver (p-value)		0.11		0.57		0.016
Healthy controls (n=38)	1.7 (2.0)		0.53 (0.98)		0.05 (0.23)

Notes: MD determined by SCID interview. Ham-Dep, depression subfactor of Ham-D; Ham-Som, somatic subfactor of Ham-D.

Abbreviations: Ham-D, Hamilton Rating Scale for Depression; MD, major depression; SCID, Structured Clinical Interview for DSM-IV.

Figure 1 Cytokine associations in cancer patients and caregivers with depression subfactors.

Notes: (A) Dotmap of cytokine associations with Ham-Som scores. (B) Dotmap of cytokine associations with Ham-Dep scores. Coefficient strength is represented by the size of the circle (blue, negative: orange, positive), with the p-value represented in gray scale.
Abbreviations: Ham-D, Hamilton Rating Scale for Depression; Ham-Dep, depression subfactor of Ham-D; Ham-Som, somatic subfactor of Ham-D.

Table 3 Impact of statistical adjustments on significant associations with Ham-Dep

Variable	Coefficient	Standard error	p-value
IL-17 in caregivers
Age	−0.13	0.04	0.006
Sex (female)	−0.16	1.06	0.89
IL-17	−1.81	0.50	0.002
IL-4 in cancer patients
Age	−0.08	0.04	0.034
Sex (female)	−0.16	0.83	0.86
BMI	0.14	0.08	0.089
Active treatment	0.82	0.89	0.36
Stage III/IV	−3.75	1.11	0.001
Hematologic	−4.48	1.40	0.003
IL-4	−0.67	0.22	0.004

Note: Ham-Dep, depression subfactor of Ham-D.

Abbreviations: BMI, body mass index; Ham-D, Hamilton Rating Scale for Depression.

Table 4 Cytokine levels and ratios in cancer patients and caregivers compared with healthy controls

Cytokine	Cancer patients vs healthy controls		Caregivers vs healthy controls
	Fold difference (p-value)	OR (p-value)	Fold difference (p-value)	OR (p-value)
IL-2	8.51 (,0.001)	3.00 (<0.001)	4.14 (<0.001)	2.12 (0.009)
IL-17	1.60 (0.002)	1.57 (0.091)	−1.65 (0.009)	0.23 (0.010)
IL-4	9.25 (,0.001)	1.93 (<0.001)	8.22 (<0.001)	2.07 (0.009)
IL-12p70	3.61 (,0.001)	1.58 (0.003)	3.18 (0.017)	1.45 (0.028)
IL-2Rα	1.80 (,0.001)	4.01 (0.003)	−1.04 (0.77)	0.28 (0.058)
IL-1ra	1.30 (0.026)	1.30 (0.42)	1.09 (0.61)	0.71 (0.48)
TNF-α:IL-4	−4.06 (,0.001)	0.78 (0.015)	−3.97 (0.006)	0.71 (0.042)
IL-6:IL-4	−3.25 (0.018)	0.86 (0.064)	−6.15 (0.007)	0.77 (0.038)

Notes: Fold differences between groups are given, with FDR-corrected p-values. Multiple regression ORs, adjusted for age and sex, are given, with FDR-corrected p-values.

Abbreviations: FDR, false discovery rate; OR, odds ratio.