Table 1.

Use/purpose, measurement method, data management and operationalization of the biomarkers included in the study.^a

Included biomarkers	Use/purpose	Measurement method	Data management & exclusions	Operationalization
Visible (to self and others)
Body mass index (BMI, kg/m2)	To estimate weight status	Weight measured with Tanita BF 522 digital floor scale; height measured with a portable stadiometer	Exclusions: <18 years of age; implausible BMI (<15 or >60)	BMI, continuous Weight status: BMI<18.5 = underweight; BMI between 18.5 and 24.99 = normal weight; BMI between 25 and 29.99 overweight; BMI>30 = obese
Waist circumference (WC, cm)	To assess central adiposity	Tape with insertion buckle; measurement taken at the midpoint between the lower rib and the upper margin of the iliac rest. Average of two measurements	Exclusions: implausible WC (<50 or >190 cm; no implausible values found in the data)	Waist circumference, continuous Abdominal obesity: WC > 102 cm for men and >88 cm for women = abdominal obesity; WC between 94 and 102 cm for men and between 80 and 88 cm for women = at risk of abdominal obesity; WC < 94 for men and WC < 80 for women = normal
%Body fat (%BF)	To assess adiposity	Bioelectrical impedance using a Tanita BF 522 scale; estimation based on respondent's age, gender and height (a “standard” body type was assumed)	Exclusions: implausible %BF (<5%; no implausible values found in the data)	%Body fat, continuous Obesity: %BF>30% for women and >25% for men = obesity; %BF ≤ 30% for women and %BF ≤ 25% for men = no obesity
Fitness
Heart rate (HR, bpm)	To assess resting heart rate	Portable monitor Omron HEM 907. Measured as the number of beats per minute; average of three readings	Exclusions: top 99.5 (≥102 bpm) and bottom 0.5 (≤44 bpm) percentiles	HR, continuous
Grip strength (GS, kg)	To measure muscular strength	Smedley dynamometer. Three measurements taken with each hand; only the maximum reading for dominant hand used	Exclusions: top 99.5 (≥66 Kg) and bottom 0.5 (≤7 Kg) percentiles	GS, continuous
Forced expiratory volume in 1 s, percent predicted (FEV1%)b Forced vital capacity, percent predicted (FVC%)b	To assess lung function	NDD Easy On-PC spirometer (England and Wales only).	Data cleaning procedures: 1) if the reading for FVC was equal to the reading of FEV, these readings were considered invalid and set to missing; 2) if the ratio of FEV to FVC was >0.95, the FVC reading was considered invalid and set to missing Percent predicted FVC (FVC%) and FEV1 (FEV1%) were estimated from valid readings of FVC and FEV adjusting for age, gender, height and ethnicity following the European Respiratory Society Global Lung Function Initiative (ERS-GLI) equations (Quanjer et al., 2012). Exclusions: implausible values (<20% or >200%)	FEV1% and FVC%, continuous
Fatigue
C-reactive protein (CRP; mg/L)	Chronic inflammation marker	Analyzed from serum using the N Latex CRP mono immunoassay on the Behring Nephelometer II Analyzer (Dade Behring, Milton Keynes, UK)	Exclusions: CRP>10 mg/L as these reflect a current infection instead of chronic inflammation (N = 705)	CRP, continuous
Fibrinogen (g/L)	Chronic inflammation marker	Analyzed from citrate plasma samples using a modification of the Clauss thrombin clotting method on the IL-ACS-TOPS analyzer	Exclusions: top 99.5 (≥4.8 g/L) and bottom 0.5 (≤1.4 g/L) percentiles	Fibrinogen, continuous
Hemoglobin (Hb, g/L)	Indicator of iron status	Measured from whole blood samples with a spectrophotometric assay on Sysmex XE-2100 analyzer	Exclusions: top 99.5 (≥17.1 g/L) and bottom 0.5 (≤9.6 g/L) percentiles	Hb, continuous Anemia: Hb < 130 g/L for men and Hb < 120 g/L for women = anemia; Hb ≥ 130 g/L for men and Hb ≥ 120 g/L for women = no anemia
Ferritin (μg/L)	Indicator of iron stores	Measured from serum samples with an electrochemiluminescent immunoassay on the Roche E170 analyzer	Exclusions: top 99.5 (≥822 μg/L) and bottom 0.5 (≤8 μg/L) percentiles	Ferritin, continuous
Cytomegalovirus antibody measurement (CMV)	To assess immunoscience (susceptibility to infection)	Two CMV antibodies measured: immunoglobulin G (IgG) indicating a past CMV infection, and immunoglobulin M (IgM) indicating a recent/current infection. Both measured from serum samples with an electrochemiluminescent immunoassay on the Roche E170 analyzer. For people with a positive/indeterminate IgM test, a confirmatory assay was conducted with an avidity test on the Mini VIDAS immunoassay analyzer		Categorized as ever having CMV infection vs. not
Disease
Blood pressure Systolic blood pressure (SBP, mmHg) Diastolic blood pressure (DBP, mmHg)	Blood pressure, risk for heart disease	Portable monitor Omron HEM 907. Mean of three valid readings used	Exclusions: implausible SBP and DBP (<40 or >300 mmHg and <30 or >200 mmHg, respectively; no implausible values found in the data)	SBP and DBP, continuous
Blood lipids Total cholesterol (mmol/L) High-density lipoprotein (HDL) cholesterol (mmol/L) Triglycerides (mmol/L)	To assess fat in the blood, risk for heart disease	Total cholesterol, HDL and triglycerides were measured from (non-fasting) blood serum using enzymatic methods with a Roche Modular P analyzer. Cholesterol measures were calibrated to the Center for Disease Control guidelines	Exclusions: top 99.5 and bottom 0.5 percentiles Total cholesterol: ≤2.8 & ≥8.9 mmoL/L HDL: ≤0.7 & ≥3.1 mmoL/L Triglycerides: ≤0.5 & ≥7.3 mmoL/L	Total cholesterol, HDL, and triglycerides continuous
Glycated hemoglobin (HbA1c, mmol/mol)	Marker of undiagnosed or poorly managed type II diabetes	Measured from whole blood using HPLC cation exchange on a Tosoh G8 analyzer	Exclusions: top 99.5 (≥86 mmoL/mol) and bottom 0.5 (≤26 mmoL/mol) percentiles	HbA1c, continuous

^aFor more detailed information please see (Benzeval et al., 2014; McFall et al., 2014).

^bAlso included in the disease category.