The health and economic burden of pertussis in Canada: A microsimulation study

Despite excellent vaccine coverage, pertussis persists in Canada, with high incidence during recent outbreaks and non-negligible incidence in non-outbreak years. While Canadian pertussis incidence is well-characterized, the full health and economic impact of pertussis have not been examined in Canada. We estimated age-specific life years (LYs) and quality-adjusted life years (QALYs) lost, and costs due to pertussis in Ontario, Canada, using a model-based approach.

We developed a microsimulation model to simulate pertussis natural history. Daily probabilities of pertussis complications, hospitalizations, and disease sequelae as well as utilities and costs for health states were literature-derived. A healthcare payer perspective was used with a lifetime time horizon. Model outcomes were compared to those from a model with no pertussis health states. Probabilistic sensitivity analyses were used to generate distributions for estimates. Economic burden was estimated by multiplying case cost estimates by annual age-specific incidence.

Overall, LYs lost per pertussis case was low, with negligible LYs lost in those aged >4 years. Infants (<6 months) had the greatest mean QALY loss per case (0.58), while adults lost only 0.05 QALYs per case. Infants experienced the greatest mean cost per case of $22,768 (95% CI: 21,144-23,406). Case costs generally declined with age, but increased in seniors (aged 65+) with mean cost of $1920 (95% CI: 1800-2033). Based on historic age-specific incidence, pertussis costs the Ontario healthcare system approximately $7.6-$21.5 M annually. In total economic cost estimates with QALYs valued at 1xGDP (3xGDP) per capita, the net impact of pertussis in Ontario was estimated at $21.7-$66.5 M annually ($50.0-$156.3 M). For all of Canada, total economic costs were estimated at $79.6-$241.3 M ($187.5-$580.5 M) annually.

The health and economic consequences of pertussis persistence are substantial and highlight the need for improved control strategies.