Cost-effectiveness analysis of hospital infection control response to an epidemic respiratory virus threat

Abstract

The outbreak of influenza A pandemic (H1N1) 2009 prompted many countries in Asia, previously strongly affected by severe acute respiratory syndrome (SARS), to respond with stringent measures, particularly in preventing outbreaks in hospitals. We studied actual direct costs and cost-effectiveness of different response measures from a hospital perspective in tertiary hospitals in Singapore by simulating outbreaks of SARS, pandemic (H1N1) 2009, and 1918 Spanish influenza. Protection measures targeting only infected patients yielded lowest incremental cost/death averted of 23,000 (US dollars) for pandemic (H1N1) 2009. Enforced protection in high-risk areas (Yellow Alert) and full protection throughout the hospital (Orange Alert) averted deaths but came at an incremental cost of up to $2.5 million/death averted. SARS and Spanish influenza favored more stringent measures. High case-fatality rates, virulence, and high proportion of atypical manifestations impacted cost-effectiveness the most. A calibrated approach in accordance with viral characteristics and community risks may help refine responses to future epidemics.

Figure 1

Markov model simulating a stochastic simulation of epidemics approach for an outbreak in a hospital institution.

Figure 2

Epidemic simulation. A) Base case simulation assuming no protection over 30 days (n = 7,500). B) Number of deaths for pandemic (H1N1) 2009, Spanish influenza, and severe acute respiratory syndrome (SARS) with different levels of alert status.

Figure 3

Incremental cost/death for 3 viruses with different alert status. Incremental cost to avert 1 additional death moving through ascending levels of alert status. Cost-effectiveness increases exponentially for pandemic (H1N1) 2009 while maintaining an almost linear fashion for both Spanish influenza and severe acute respiratory syndrome (SARS). The incremental cost/death averted ratio is lower for Alert Orange compared to Alert Yellow for SARS.

Figure 4

Sensitivity analysis for case-fatality rate (black line), % exposure reduction (red line), and secondary attack rate (blue line). Exponential graphs show poor cost-effectiveness at extremes of low case-fatality rate and low transmissibility (high % exposure reduction and low secondary attack rate).