Table 1.

Sample characteristics

		Cortisol sample (N = 4761)			C-reactive protein sample (N = 5784)
Variables	Levels	Missing (%)	Mean (sd)	Frequency (%)	Missing (%)	Mean (sd)	Frequency (%)
Depressive symptoms (CESD-8)
Overall score		1.0	1.20 (1.69)		0.8	1.13 (1.64)
Cognitive-affective score		1.0	0.60 (1.19)		0.7	0.57 (1.15)
Somatic score		0.4	0.71 (0.94)		0.3	0.67 (0.91)
Stress biomarkers
Hair cortisol (log, pg/mg)		–	0.89 (0.56)		39.5	0.88 (0.57)
Plasma C-reactive protein (log, <10 mg/L)		26.6	0.37 (0.92)		–	0.36 (0.92)
Demographics
Sex	Men	–		33.0			45.4
	Women			67.0			54.7
Age		–	67.47 (9.39)		–	66.41 (9.09)
Wealth (quintiles)	1 (lowest)	1.7		18.0	1.7		17.1
	2			19.6			19.4
	3			20.3			20.7
	4			21.0			21.5
	5 (highest)			21.2			21.3
Lifestyle indicators
Current smoker		–		11.0	–		11.1
Physical activity	Low	–		60.2	–		56.1
	High			39.8			43.9
Alcohol use (frequency)		8.3	4.44 (2.23)		8.1	4.26 (2.17)
Body mass index (BMI)		4.3	28.27 (5.40)		2.9	27.98 (4.95)
Chronic conditions
CVD		–		22.6	–		18.8
Cancer		–		5.4	–		4.6
Chronic lung disease		–		4.4	–		4.1
Diabetes		–		10.3	–		9.2
Medications
Anti-inflammatory/antihypertensive		–		45.3	–		42.9
Antidepressants		–		11.8	–		10.5
Hair characteristics
Hair dyed		0.6		33.6	–		–
Season hair collection	Summer	–		23.4	–		–
	Autumn			42.7
	Winter			26.7
	Spring			7.2
Phase of hair analysis	1 (2015)	–		53.6	–		–
	2 (2018)			46.4

Data source: ELSA, wave 6. sd standard deviation, CESD-8 eight-item centre for epidemiological studies-depression scale, CVD cardiovascular disease