Measuring high-sensitivity cardiac troponin T blood concentration in population surveys.

Introduction: 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).

Conclusion: The measurement of HS-CTnT plasma concentration within large nationally-representative surveys such as the Health Survey for England is feasible.