Andrew J. Rosner

Objective: Pertussis is a highly contagious infection affecting mainly children. Acellular pertussis vaccines were recently introduced in Canada based on evidence of improved safety and efficacy overwhole cell vaccines, the current standard of care. The following study reports the economic impact of replacing the whole cell vaccine (wP) by a new acellular vaccine (aP) in the Ontario pertussis immunisation programme. Design: For a hypothetical cohort of 100 000 children from birth to the age of 8 years, the costs and consequences of pertussis vaccination with either aP or wP were compared. A decision analytical modelwas constructed for vaccine delivery, treatment of pertussis cases and vaccine adverse events, with analyses from the viewpoints of the Ontario Ministry of Health and society. Main outcome measures and results: The main outcomes were expected number of pertussis cases, hospitalisations, and workdays lost by parents. Data on vaccine effectiveness, pertussis incidence, and other parameters used in the model were from published literature. Costs were discounted at 5%, and extensive sensitivity analyses were undertaken. Over 8 years, in a cohort of 100 000 children, the introduction of aP would prevent 10 500 cases of pertussis, avoiding 504 hospital admissions and 73 500 days of work absence. For Ontario, healthcare cost savings over the same period would amount to 275 585 Canadian dollars ($Can), and societal savings to $Can9 752 864 (1997values). Results were sensitive to both incidence of pertussis and vaccine efficacy. Conclusion: This study suggests that even though the new acellular vaccine has a higher acquisition cost than the currentwhole cell vaccine, its improved efficacy and safety result in overall cost savings.

Objective: The aim of this study was to evaluate the cost effectiveness of multitherapy treatment strategies in the prevention of vertebral fractures in postmenopausal women with osteoporosis. Design: A retrospective, incremental cost-effectiveness analysis was conducted from a societal perspective. It compared 9 treatment strategies over 3 years and incorporated the willingness of patients to initiate and continue each therapy. Main outcome measures and results: Four nondominated strategies formed the efficient frontier in the following order: (i) calcium → no therapy; (ii) ovarian hormone therapy (OHT) → calcium → no therapy [166 Canadian dollars ($Can)]; (iii) OHT → etidronate → calcium → no therapy ($Can2331); and (iv) OHT → alendronate → calcium → no therapy ($Can40 965). The figures in parentheses are the incremental costs per vertebral fracture averted to move to that strategy from the previous strategy for patients who had undergone a hysterectomy. Conclusions: We identified 4 efficient multi-therapy strategies for the treatment of vertebral osteoporosis in postmenopausal women, 2 of which were consistent with the practice guidelines of the Osteoporosis Society of Canada. Decisionmakers may select from among these efficient strategies on the basis of incremental cost effectiveness.