|Cost effectiveness of high-risk HPV DNA testing for cervical cancer screening in South Africa
|Vijayaraghavan A, Efrusy M, Lindeque G, Dreyer G, Santas C
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 objective was to determine the cost-effectiveness of cervical cancer screening strategies using human papillomavirus (HPV) testing. The authors concluded that HPV testing to screen for cervical cancer and its precursors was cost-effective in South Africa. The methodology had some limitations and more details of the methods used to obtain the effectiveness and cost data should have been reported. The results were reported in full, but, given the limitations of the study, the authors’ conclusions should be treated with caution.
Type of economic evaluation
The objective was to determine the cost-effectiveness of several cervical cancer screening strategies using human papillomavirus (HPV) testing in South Africa.
The cervical cancer screening strategies were: no screening; conventional cytology; cytology followed by HPV testing for triage of equivocal cytology results; HPV testing followed by colposcopy for HPV-positive women; HPV testing followed by cytology for triage of HPV-positive women; and both cytology and HPV testing.
South Africa/primary care.
A decision analytic Markov model was used to model the costs, survival and quality of life associated with screening and treating cervical cancer. The model had a hypothetical cohort of 100,000 South African women from age 13 years. The time horizon was lifetime. The authors reported that a societal perspective was adopted.
The clinical and effectiveness estimates were derived from extensive literature reviews of published studies, and expert opinion. The main effectiveness parameter was the sensitivity and specificity of each of the screening options. These data were derived from published studies.
Monetary benefit and utility valuations:
The utility data were derived from a published study. The authors only provided a reference for this study and no further details.
Measure of benefit:
Quality-adjusted life-years (QALYs) gained were the summary benefit measure. As the benefits could be incurred over the lifetime of the patient, future benefits were discounted at an annual rate of 3%.
The direct costs were those associated with clinic visits; diagnostic and screening tests; treatment options, which included loop electrode excision procedure, cryotherapy, hysterectomy, chemoradiation, and radiotherapy; and the treatment of cervical cancer at different stages. The authors reported that these costs were derived using micro-costing methods and the unit costs were obtained from the South African Uniform Patient Fee Schedule. The indirect costs were patient time costs, which included time spent for cervical cancer screening, diagnosis, and treatment. The authors reported that the indirect costs resulting from morbidity were not included as these were incorporated in the utilities. The price year was 2006 and, as costs could be incurred over the lifetime of the patient, future costs were discounted at an annual rate of 3%. All costs were reported in South African rand (ZAR) and US dollars ($). The exchange rate used was $1 equals ZAR 6.7.
Analysis of uncertainty:
A series of one-way sensitivity analyses was undertaken to assess the robustness of the model’s results. The ranges for the clinical variables were based on the literature and on expert opinion, whereas those for costs were a variation of ± 25% of the base-case estimates.
The average QALYs gained were 23.6811 with no screening, 23.6924 with cytology, 23.7126 with cytology followed by HPV test, 23.7192 for HPV test followed by cytology, 23.7286 for HPV test followed by colposcopy, and 23.7318 for HPV test and cytology.
The average cost per patient was ZAR 91,767 with no screening; ZAR 92,241 with cytology; ZAR 92,185 with cytology followed by HPV test, ZAR 92,463 for HPV test followed by cytology, ZAR 92,477 for HPV test followed by colposcopy, and ZAR 92,557 for HPV test and cytology.
The costs and benefits were combined using an incremental cost utility ratio (ICUR; the additional cost per QALY gained).
Compared with no screening, the ICUR for cytology was ZAR 41,977 ($6,263). Compared with cytology, cytology followed by HPV test was dominant, which means it was more effective and less costly. Compared with cytology followed by HPV test, the ICUR for HPV test followed by cytology was ZAR 41,121 ($6,287). Compared with HPV test followed by cytology, the ICUR for HPV test followed by colposcopy was ZAR 1,541 ($230). Compared with HPV test followed by colposcopy, the ICUR for HPV test and cytology was ZAR 25,414 ($3,792).
The sensitivity analysis showed that these results were most sensitive to variation in the rate of progression or regression to cervical intraepithelial neoplasia (CIN), quality of life, and cost of colposcopy or biopsy.
The authors concluded that HPV testing to screen for cervical cancer and its precursors was a cost-effective strategy in South Africa.
The interventions were reported clearly and in detail.
The authors reported that the clinical and effectiveness data were derived from extensive literature reviews and expert opinion. No details of the methods used to identify the studies, nor of the methods used to elicit expert opinion, were provided. As a result, it is not possible to determine if a systematic review was undertaken or whether all the relevant information was included.
The authors explicitly reported the perspective and all the cost categories and costs, relevant to this societal perspective, appear to have been included, with the exception of productivity losses due to morbidity. They reported that the impact of these costs was already accounted for in the utilities used to generate the QALYs. There is much debate as to whether these productivity losses should be included and it is not possible to assess whether this was appropriate. The authors reported that a micro-costing approach was used to determine the direct costs, but very few details of the methods used were provided. The sources of unit costs were adequately reported. The price year, currency conversions used, time horizon, and discount rate were all reported.
Analysis and results:
A Markov model was used to synthesise all the available evidence. The methods used were reported, with a diagram of the model. A series of one-way sensitivity analyses assessed the robustness of the model’s results. Although this type of analysis goes some way towards evaluating uncertainty, probabilistic sensitivity analysis would have been a more thorough way to capture the overall model uncertainty. In their discussion, the authors reported the limitations of their study, the main one being the use of multiple sources with varied study designs to inform the model. When calculating the incremental cost-utilities, a number of interventions were dominated or extendedly dominated. Once identified, these dominated interventions should be discarded, so that the next intervention can be compared with the best possible alternative. This was not done.
Overall, the methodology had some limitations and more details of the methods used to obtain the effectiveness and cost data should have been reported. The results were reported in full, but, given the limitations of the study, the authors’ conclusions should be treated with caution.
Funded by a grant from Roche Molecular Systems, Inc.
Vijayaraghavan A, Efrusy M, Lindeque G, Dreyer G, Santas C. Cost effectiveness of high-risk HPV DNA testing for cervical cancer screening in South Africa. Gynecologic Oncology 2009; 112(2): 377-383
Other publications of related interest
Goldie SJ, Gaffikin L, Goldhaber-Fiebert JD, Gordillo-Tobar A, Levin C, Mah C, et al. Cost-effectiveness of cervical-cancer screening in five developing countries. New England Journal of Medicine 2005; 353: 2158-2168.
Goldie SJ, Kuhn L, Denny L, Pollack A, Wright TC. Policy analysis of cervical cancer screening strategies in low-resource settings: clinical benefits and cost-effectiveness. JAMA 2001; 285: 3107-3715.
Subject indexing assigned by NLM
Adolescent; Adult; Cervical Intraepithelial Neoplasia /economics /pathology /therapy /virology; Computer Simulation; Cost-Benefit Analysis; Cytological Techniques /economics; DNA, Viral /analysis; Female; Genetic Techniques /economics; Humans; Markov Chains; Middle Aged; Models, Economic; Models, Statistical; Neoplasm Staging; Papillomaviridae /genetics /isolation & Papillomavirus Infections /complications /economics /virology; South Africa; Uterine Cervical Neoplasms /economics /pathology /therapy /virology; Young Adult; purification
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Date abstract record published