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. Author manuscript; available in PMC: 2017 May 1.
Published in final edited form as: Soc Sci Med. 2016 Mar 3;157:138–147. doi: 10.1016/j.socscimed.2016.02.041

Table 1.

Biomarker index components

Biomarker Description High-risk definition
Clinical cardiovascular and metabolic markers
   Systolic blood pressure The maximum arterial blood pressure during
each heartbeat.		 > 140 mmHG
   Diastolic blood pressure The minimum arterial blood pressure during
each heartbeat.		 > 90 mmHG
   Total cholesterol A measure of cholesterol that includes low-
density lipoprotein (LDL, or “bad” cholesterol)
and high-density lipoprotein HDL, or “good”
cholesterol). Excess cholesterol contributes to
plaques in blood vessels.		 >= 240 mg/dL
   High-density lipoprotein (HDL) cholesterol “Good” cholesterol; helps remove cholesterol
from arteries.		 < 40 mg/dL
   Triglycerides A lipid widespread in adipose tissue, circulates
in the blood as lipoproteins.		 >= 200 mg/dL
   Glycosylated hemoglobin A protein created when hemoglobin binds to
glucose. A measure of blood glucose levels
over the past several months.		 > 6.5%
   Insulin resistance Estimated from the homeostatic model
assessment (HOMA-IR). Derived from fasting
blood glucose levels.		 Highest sex-specific quintile
   Body mass index (BMI) Weight in kilograms / height in meters squared.
A measure of body fat.		 > 30 or <18.5
   Waist circumference Waist circumference in centimeters. A marker
of abdominal fat.		 > 102 cm for men
> 88 cm for women
Heart rate variability markers
   Mean heart rate Mean heart rate over 24 hours (beats per
minute).		 Highest sex-specific quintile
   Ratio of daytime to nighttime heart rate Ratio of mean daytime heart rate (8:00 am –
8:00 pm) to mean nighttime heart rate (12:00
am - 4:00 am).		 Lowest sex-specific quintile
   Standard deviation of normal beat-to-beat
intervals (SDNN)		 Standard deviation of all normal intervals over
24 hours. Measure of longer term variability.		 < 100 ms
   Root mean square of successive differences in
normal beat-to-beat intervals (RMSSD)		 The square root of the mean of the squares of
successive differences between adjacent normal
heart beats. Measure of shorter term variability.		 Lowest sex-specific decile
Inflammation markers
   C-reactive protein Protein that is part of the inflammatory
response. Increases in response to interleukin-6.		 > 3 mg/L
   Interleukin-6 Inflammatory cytokine, promotes production of
inflammatory proteins.		 Highest sex-specific quintile
   Fibrinogen Protein that assists in blood clot formation.
Increases as part of the inflammatory response.		 Highest sex-specific quintile
Neuroendocrine markers
   Cortisol Stress hormone produced by the adrenal gland. Highest sex-specific quintile
   Dehydroepiandrosterone sulfate (DHEAS) Steroid hormone produced by the adrenal
gland. May counterbalance the effect of
cortisol.		 Lowest sex-specific quintile
   Epinephrine Hormone produced by the adrenal gland. Part
of the fight-or-flight response.		 Highest or lowest sex-specific decile
   Norepinephrine Hormone produced by the adrenal gland.
Precursor to epinephrine.		 Highest sex-specific quintile

Note: Each biomarker risk index represents a count of the number of biomarkers for which a participant falls in the high-risk category.