Revised estimates of the cost-effectiveness of HPV vaccination: accounting of quality of life losses and medical expenditures in life years gained

In 2008, a vaccine against HPV types 16 and 18 was introduced in the Dutch National Immunisation Programme (NIP) for 12-year old girls, in order to prevent ca. 70% of all cervical cancers in later life. Several studies have been performed that provide cost-effectiveness analyses for this vaccine. In this thesis, it is argued that quality of life losses in life years gained should be revised by using age and gender-adjusted quality of life parameters that are not 1.0 in absence of the disease under investigation. Furthermore, none of the performed Dutch studies take into account the future unrelated medical costs that will be made by preventing cervical cancer mortality. In this thesis, a more accurate incremental cost-effectiveness ratio (ICER) is calculated, using the software package PAID 1.0 to determine unrelated medical expenditures in gained life years. Hereby, this thesis contributes to the discussion whether and how indirect unrelated medical costs should be included in cost-effectiveness analyses. To calculate the ICER of the HPV vaccination in The Netherlands, I use survival curves for a cohort of 100,000 vaccinated and 100,000 unvaccinated girls, provided by Rogoza et al. in their study published in 2009. I extend this static model by including future medical expenditures per age and the age-adjusted quality of life parameters for Dutch women. ICER increases when future unrelated medical costs are included in the calculation. I found an ICER of €19,406 per QALY, compared to the ICER from Rogoza et al. of €18,500 per QALY. Furthermore, I found ICER increasing when age-adjusted quality of life parameters were used (€22,238 per QALY). Considering both indirect unrelated medical costs and age-adjusted quality of life, ICER was €23,329 per QALY, using discount rates of 4% for costs, and 1.5% for effects. In the sensitivity analysis, I found the incremental costs-effectiveness ratio to be highly sensitive to discount rate. In The Netherlands, different discount rates are used, which I found can lead to either a more favourable ICER, or one that is less favourable. I showed that, since vaccination requires spending costs now and receiving benefits in the far future, the higher the discount rates on costs and effects are, the less favourable ICER is rendered. In conclusion, I showed that, when a threshold for preventive medical practice of €20,000 is used, HPV vaccination in 12 year old girls may not be considered cost-effective.