title: Measuring high-sensitivity cardiac troponin T blood concentration in population surveys.
abstract: BACKGROUND
  The blood test for high-sensitivity cardiac troponin T (HS-CTnT) has been proposed as a marker of cardiovascular risk in the general population, as it is associated with subsequent incidence of cardiovascular events and mortality. We aimed at evaluating the feasibility of HS-CTnT testing within large nationally-representative population surveys in which blood samples are collected during household visits, shipped using the standard civil postal service, and then frozen for subsequent analyses.
  
  
  METHODS
  The Health Survey for England (HSE) consists of a series of annual surveys beginning in 1991. It is designed to provide regular information on various aspects of the nation's health and risk factors. We measured HS-CTnT in the blood of 200 people from the HSE 2016 wave, then froze and stored their blood samples at -40°C for 5-10 weeks, and then thawed and retested them to appreciate the extent of within-person agreement or test-retest reliability of the two measurements.
  
  
  RESULTS
  The Cronbach's Alpha (Scale Reliability Coefficient) and the Interclass Correlation Coefficient (two-way mixed-effects model for consistency of agreement at individual level) were 0.97 (95%CI = 0.96-0.99) and 0.95 (95%CI = 0.94-0.96) respectively. The time delay from blood withdrawal to analysis and storage (1-4 days) did not affect the results, nor did the freezing time before the retest (5-10 weeks).
  
  
  CONCLUSIONS
  The measurement of HS-CTnT plasma concentration within large nationally-representative surveys such as the Health Survey for England is feasible.
authors.affiliation: London School of Hygiene & Tropical Medicine, London, United Kingdom.|Department of Epidemiology and Public Health, UCL, London, United Kingdom.
authors.forename: Antonio Ivan
authors.identifier: http://orcid.org/0000-0001-8045-2346
authors.initials: AI
authors.lastname: Lazzarino
authors.affiliation: Department of Epidemiology and Public Health, UCL, London, United Kingdom.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Mindell
mesh_terms: D004739:England / Q000453:epidemiology; D006306:Health Surveys; D006801:Humans; D015203:Reproducibility of Results; D020107:Troponin T / Q000097:blood*
chemical_list: D020107:Troponin T