ECONOMIC BURDEN OF PERTUSSIS IN ONTARIO

Purpose: This study was undertaken to estimate age-specific quality-adjusted life years (QALYs) lost, life years (LYs) lost, and costs associated with pertussis in Ontario, Canada.

Method: A microsimulation model was designed in TreeAge Pro to estimate the age-specific distribution of QALYs, LYs and costs for pertussis in Ontario. We simulated disease progression through susceptible, exposed, catarrhal, paroxysmal, convalescent, and recovered phases of pertussis illness and compared results to a model with only susceptible and dead health states. Daily probabilities of pertussis complications, hospitalizations, and disease sequelae as well as utilities and costs for the health states were derived from the literature. A healthcare payer perspective was used with a lifetime time horizon. QALYs lost, LYs lost, and costs were discounted at 5% per annum. Probabilistic sensitivity analysis with 100,000 model realizations per age group was used to generate estimates. Budget impact was assessed by multiplying average case cost estimates by annual age-specific incidence from Public Health Ontario. Using 1-3x GDP per capita for a willingness to pay range, we quantified the QALY loss to assess the net monetary impact of pertussis. 

Result: Infants <6mo showed the greatest QALY loss (0.141 QALYs or 51.5 quality-adjusted life days). QALY loss was smallest in the seniors ≥65y (0.011 QALYs or 4.01 quality-adjusted days). Preliminary results suggest that pertussis costs in Ontario generally decline with age with infants <6mo having a mean (sd) cost per case of $14,065 ($26,200) and seniors ≥65y costing $1,946 ($8,437). Cases among children, youth, and adults were estimated to cost $5,319 ($11,946), $1,447 ($4,227), and $1,379 ($2,698) respectively. These results suggest that, based on current age-specific incidence, pertussis costs the Ontario healthcare system approximately $1.24M annually and as much as $3.97M in an outbreak year. When QALYs were included at 1xGDP (3xGDP) per capita, the net monetary impact of pertussis in Ontario was assessed at $2.3M ($4.46M) annually and $7.9M ($15.75) in an outbreak year.

Conclusion: The health and economic consequences of pertussis persistence in Ontario are substantial and highlight the need for improved strategies for the use of existing vaccines. Research is currently underway to evaluate the effectiveness and cost-effectiveness of a decennial adult acellular pertussis booster program compared to the one-time only program for adults in Ontario.