|Human papillomavirus testing with Pap triage for cervical cancer prevention in Canada: a cost-effectiveness analysis
|Kulasingam SL, Rajan R, St Pierre Y, Atwood CV, Myers ER, Franco EL
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
The aim was to assess the potential cost-effectiveness of including tests for human papillomavirus (HPV) in the cervical cancer screening programme in Canada. The authors concluded that HPV testing starting at 25 years old, with Papanicolaou smear triage for those with positive tests, could be more cost-effective than the recommended strategy for screening. The study was satisfactorily performed, in the selection of the clinical and economic data, and transparently reported. The authors' conclusions appear to be appropriate.
Type of economic evaluation
Cost-effectiveness analysis, cost-utility analysis
The aim was to assess the potential cost-effectiveness of including tests for human papillomavirus (HPV) in the cervical cancer screening programme, for Canada as a whole and for the provinces of Alberta, Newfoundland, and Ontario.
The interventions were 27 screening strategies, which were based on the Papanicolaou (Pap) smear test alone, the HPV test alone, or the Pap and HPV tests together, starting at the ages of 18 years or 25 years, with screening intervals of one, two, three, or five years. This included the recommended strategy of annual Pap screening starting at 18 to 21 years and repeated every three years. These strategies were compared with no intervention.
: A published state-transition Markov decision model was adapted to estimate the lifetime clinical and cost impact of the 27 screening strategies, using national and regional data from Canadian studies and databases, and published evidence. The authors stated that the perspective was that of the health system.
The evidence for the main clinical data, which were the sensitivity and specificity of HPV testing versus Pap testing, came from a recently published trial, the Canadian Cervical Cancer Screening Trial (CCCaST, Mayrand, et al. 2006, see ‘Other Publications of Related Interest' below for bibliographic details). Other key clinical parameters included the incidence and prevalence of HPV and cancers, and life expectancy.
Monetary benefit and utility valuations:
The utility estimates were derived from a small US study.
Measure of benefit:
The benefit measure was the number of life-years (LY) gained. Quality-adjusted life-years were only used in the sensitivity analysis, due to the quality of the utility evidence. Future benefits were discounted at a rate of 3% per year.
The analysis included the direct medical costs for Pap and HPV tests, fees for professionals, and the costs of care for cancer by stage. These costs were from a combination of provincial fee schedules, government databases, and published sources. Where necessary, they were adjusted to provincial costs, using the costs per weighted case by province from the Canadian Institute of Health Information. They were in 2006 Canadian dollars (CAD) and future costs were discounted at a rate of 3% per year.
Analysis of uncertainty:
Univariate sensitivity analyses were performed, along with probabilistic sensitivity analysis, to explore the impact of the overall uncertainty surrounding the model parameters.
With no intervention, the expected number of all-stage cancers was 2,145. As a rule, screening strategies that started at 18 years old increased the number of false-positive test results, but did not greatly affect the number of cancers, compared with the same strategy starting at 25 years old. For example, HPV with Pap triage every three years starting at 18 years had 9,872 false-positives and 437 cancers, compared with 5,585 false-positives and 467 cancers, starting at 25 years.
HPV testing followed by Pap triage was generally associated with a reduction in costs and greater increases in life expectancy, compared with the screening strategy recommended in Canada, resulting in a cost per life-year gained of less then CAD 50,000.
The authors concluded that HPV testing, starting at 25 years old, with Pap triage for those with positive tests, could be more cost-effective than the recommended strategy for screening in Canada.
The interventions were appropriate comparators, as a range of strategies were compared and this included the usual practice in the study setting. These strategies are likely to be relevant for other settings.
The use of Canadian data and published evidence was appropriate to derive estimates relevant to the Canadian health care system, but the process of identifying these studies was not described and it is unclear whether the best available evidence was used. The authors did not explicitly state that the CCCaST was the only relevant trial available for the sensitivity and specificity data, but this was implied. The authors acknowledged that the utility data were limited by the quality of the study from which they were derived, and consequently they were only used in the sensitivity analyses. The use of unadjusted life-years was appropriate, for the main analysis.
The perspective was clearly defined and all the relevant costs appear to have been included. The cost estimates were provided, in detail in a table, and they were fully referenced. The costs were appropriately adjusted to regional estimates and the methodology was described. Details, such as the price year and discounting, were provided.
Analysis and results:
The incremental analysis was appropriate for assessing the cost-effectiveness of the screening strategies. The parameter uncertainty was assessed using univariate and probabilistic sensitivity analyses. The reporting of the base case and the sensitivity analyses was sufficient. The authors acknowledged and discussed the limitations of their study.
This cost-effectiveness study was satisfactorily performed, in the selection of the clinical and the economic data, and was transparently reported. The authors' conclusions appear to be appropriate.
Funding received from the National Cancer Institute of Canada, the Canadian Institutes of Health Research, Fonds de la recherche en sante du Quebec, the US National Institute of Health, and Merck-Frosst, Inc, Canada.
Kulasingam SL, Rajan R, St Pierre Y, Atwood CV, Myers ER, Franco EL. Human papillomavirus testing with Pap triage for cervical cancer prevention in Canada: a cost-effectiveness analysis. BMC Medicine 2009; 7:69
Other publications of related interest
Mayrand MH, Duarte-Franco E, Coutlee F, Rodrigues I, Walter SD, Ratnam S, Franco EL. Randomized controlled trial of human papillomavirus testing versus Pap cytology in the primary screening for cervical cancer precursors: design, methods and preliminary accrual results of the Canadian cervical cancer screening trial (CCCaST). International Journal of Cancer 2006; 119(3): 615-623.
Subject indexing assigned by NLM
Adolescent; Adult; Alberta; Cervix Uteri /pathology /virology; Cost-Benefit Analysis; Female; Humans; Mass Screening /methods; Newfoundland and Labrador; Ontario; Papanicolaou Test; Papillomavirus Infections /diagnosis; Uterine Cervical Neoplasms /economics /prevention & Vaginal Smears /economics; Young Adult; control /virology
Date bibliographic record published
Date abstract record published