Purpose: Cardiac First-Responder (CFR) schemes aim to improve survival from Sudden Cardiac Arrest (SCA), by reducing the time until administration of life-saving defibrillation, with volunteers paged to respond to possible SCA incidents alongside the Emergency Medical Services (EMS). Observational CFR trials have produced varying results in different geographical regions. A Monte-Carlo simulation-based model has been constructed to capture the varying impact of mobile CFR schemes in different geographical regions, as part of a cost-utility analysis. Calculation results are presented for a particular rural region of the UK.
Methods: Two interventions are compared over a 5-year period: treatment of SCA through standard EMS versus standard EMS combined with a CFR scheme. Within the model, occurrence of SCAs across a geographical region is assumed to follow a Poisson process, based on the at-risk population in small areas. For each SCA, the response-times of the EMS, together with any CFR responses (dependent on the roster scheme) are quantified. Parametric accelerated failure-time models are used to model these, depending on geographical location and other influential covariate information. The effectiveness of the scheme in a particular geographical region is determined by substituting response-times in a logistic-regression survival-to-hospital-discharge model, and utilising published quality-of-life utility-scores and life-expectancies. Incremental costs include the cost of capital set-up, annual revenue, additional hospitalisation and long-term care costs. After model-validation, the Incremental Cost-Effectiveness Ratio (ICER) has been calculated for a rural region, extending a previous one-way sensitivity analysis and incorporating second-order probabilistic sensitivity analysis.
Results: Second-order probabilistic sensitivity analyses suggest response-times would be improved in this rural region through the addition of a 31-person CFR scheme with 45.9% (IQR:[43.8%-48.3%]) of SCAs reached within 8 minutes, compared to 35.6% (IQR:[34.5%-36.7%]) under EMS-only. An additional 16.5 QALYs would be gained (IQR:[8.1-26.5]) for the population of 185,795. The ICER was £48,172/QALY (IQR:[£33,861-£85,893]). The ICER was less than the nominal National Health Service (NHS) National Institute of Clinical Excellence threshold of £30,000 in 17% of simulations. The ICER was sensitive to alterations in volunteer availability; sensitivity of the dispatch mechanism and training costs.
Conclusion: The scheme would not be the most efficient use of NHS resources in this particular rural geography. However, it could start to address the existing imbalance in emergency-response provision found between rural and urban regions.
Candidate for the Lee B. Lusted Student Prize Competition