ARCHIVED - Recommendations on a Human Papillomavirus Immunization Program

 

Appendix 4

Pharmaco-economic evidence supporting the recommendations

For Canada, a cost-effective intervention is considered to be one in which the cost per quality-adjusted life year (QALY) gained is less than the per capita gross domestic product (approximately $40,000) and an extremely cost-effective intervention is considered to be one in which the cost per QALY gained is less than $20,000.

One female cohort selected from grade 4–8 (aged 9-14)

Grades 4 (9 years old) and 5 (10 years old): None of the cost-effectiveness studies on HPV vaccine published to date evaluated the impact of HPV vaccination in a 9- or 10-year-old. However, based on results from grades 6, 7 and 9 one would anticipate the program to be cost-effective, especially if there is an existing hepatitis B program on which the HPV could be piggybacked.

Grade 6 (11 years old): The model developed in British Columbia by Pourbohloul and Gunther(42) estimated that vaccination of 11-year-old girls (grade 6) would result in a decrease of 43.0% in HPV 16/18-related cervical cancer. The cost-effectiveness, calculated by Marra and colleagues(34), showed a cost of $24,945 per QALY gained compared with no vaccination. This program would be considered to be cost-effective.

Grade 7 (12 years old): All cost-effectiveness studies modelled in the United States published to date looked at the impact of vaccination of 12-year-old girls. Sanders and Taira(36) estimated a reduction of 20% in the incidence of cervical cancer at a cost of $22,755 per QALY gained with vaccination against 13 high-risk HPV types, as compared with no vaccination. Kulasingam and Myers(35) assumed vaccination against 70% of high-risk HPV types (including HPV 16/18) and obtained a 15% reduction in cervical cancer incidence at a cost of $92,677 per life year gained for vaccination (and biennial screening starting at age 18 years) compared with no vaccination. Goldie and colleagues(38) used a societal perspective in their model and estimated a 58.1% reduction in the incidence of cervical cancer at a cost of $24,300 per QALY gained with a bivalent vaccine against HPV 16/18 versus no vaccination. In the model by Taira(30), the incidence of cervical cancer was decreased by 61.8% at a cost per QALY gained of $14,583 with vaccination against HPV 16/18 compared with no vaccination. Finally, Elbasha et al.(32) assessed the impact of vaccination against HPV 6/11/16/18 and projected a decrease of 75% in the incidence of cervical cancer; this reduction was associated with an incremental cost per QALY of $2,964 compared with no vaccination. This program would be considered to be cost-effective.

Grade 9 (14 years old): The model developed in British Columbia by Pourbohloul and Gunther(37) estimated that vaccination of 14-year-old girls (grade 9) would result in a decrease of 41.0% in HPV 16/18-related cervical cancer. The cost-effectiveness calculated by Marra and colleagues(34) showed a cost of $24,530 per QALY gained compared with no vaccination. This program would be considered to be cost-effective.

Two female cohorts between grade 4 and grade 12

To date, none of the cost-effectiveness studies modeled in the United States looked at this type of vaccination strategy. For the BC model, Pourbohloul and Gunther(42) evaluated a program combining vaccination of 11-year-olds with 3 years of catch-up for 14-year-olds. With this program, the projected reduction in the incidence of cervical cancer was 46.0%. Marra and colleagues(34) showed a cost of $25,417 per QALY gained for this program compared with no vaccination. This program would be considered to be cost-effective.

School-based program, many cohorts (at minimum one cohort of girls from each elementary, junior and high school aged groups, i.e. a total of three cohorts).

To date, none of the cost-effectiveness studies modeled in the United States or Canada have evaluated this type of vaccination strategy. However, clinical studies have shown high immunogenicity in preadolescents and adolescents aged 9-14(16). A school-based program is also an effective way to obtain higher vaccination coverage at a lower cost.

All females for recommended ages of 9 to 26 years (option 1 is included in this option; this is a catch-up program)

Taira(30) estimated the reduction in lifetime risk of cervical cancer among 24-year-old women who received catch-up vaccination (35%), but unfortunately they did not calculate the costs associated with this strategy. Elbasha and colleagues(32) also evaluated the impact of three different vaccination strategies, including a catch-up program. One of these included female-only vaccination and looked at vaccination of 12-year-old girls with a catch-up program for females aged 12 to 24 years. The catch-up program was associated with a long-term reduction in the incidence of cervical cancer similar to that of the 12-year-old program only (~75% reduction). However, the decrease in the incidence was observed earlier with the catch-up program. Vaccination of 12-year-old girls with a catch-up program was associated with an incremental cost per QALY of $4,666 compared with vaccination of 12-year-olds only.

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