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Cost-effective analysis of mass screening for cervical cancer in Japan |
Matsunaga G, Tsuji I, Sato S, Fukao A, Hisamichi S, Yajima A |
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Record Status 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. Health technology Pap smear testing within a mass screening programme for cervical cancer in Japan.
Economic study type Cost-effectiveness analysis.
Study population A hypothetical cohort of 200,000 asymptomatic women aged 30 years.
Setting Hospital. The study was carried out in Japan.
Dates to which data relate Effectiveness data were collected from studies published between 1989 and 1994. Cost data were collected from 1989-1994 sources. The price year was not reported.
Source of effectiveness data Effectiveness data were derived from a literature review.
Modelling A 40-year decision analytic model was used to determine the cost-effectiveness of the two screening strategies.
Outcomes assessed in the review The review assessed the following outcomes: incidence rate of cervical cancer, mortality rate of uterine cancer and other causes, stage distribution among cancers detected in the screening programme and in the "no screening" programme, survival rate of cervical cancer, efficacy of Pap smear, and life expectancy.
Study designs and other criteria for inclusion in the review Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Summary statistics from individual studies.
Number of primary studies included At least 6 primary studies were included.
Methods of combining primary studies Investigation of differences between primary studies Results of the review One-third of cases with negative Pap smear results would progress to the invasive cancer state. Among cancers detected in the no screening programme, 30% of cases were carcinoma in situ (CIS) and 70% of cases were invasive cancer. Among cancers detected in the screening programme, 94% of cases were CIS and 6% of cases were invasive cancer. Five-year survival rates of cases with cervical cancer were 100% for patients with CIS and 67% for those with invasive cancer. The sensitivity and specificity of the Pap smear were estimated to be 90% and 98%, respectively.
Measure of benefits used in the economic analysis The number of life years saved was used as the measure of benefits. Benefits were discounted at an annual rate of 5%.
Direct costs Direct costs were discounted at an annual rate of 5%. Quantities and costs were reported separately. Direct costs included the screening cost, diagnosis costs, costs for initial treatment, and costs for terminal treatment. The quantity/cost boundary adopted was that of society. The estimation of quantities and costs was based on actual data. The screening charge was derived from a 1989 source. The costs for medical treatment were derived from the Department of Obstetrics and Gynaecology, Tohoku University School of Medicine. The price year was not reported.
Statistical analysis of costs Currency US dollars ($), with $1 = 100 Japanese Yen.
Sensitivity analysis Sensitivity analyses were conducted on the following parameters: charge of screening tests ($10 - $60), sensitivity of screening test (80% - 100%), specificity of screening test (80% - 100%), frequency of CIS in the screening programme (88% - 100%), initial costs for patients with invasive cancer ($10,000 - $100,000), terminal costs for patients with invasive cancer ($10,000 - $100,000), incidence rate of cervical cancer (0.1 - 2.0 times).
Estimated benefits used in the economic analysis The number of life years saved was 6,346 years without screening and 7,689 with mass screening.
Cost results The total costs of the no screening and the screening programmes amounted to $5,422,000 and $59,977,000, respectively.
Synthesis of costs and benefits The incremental cost per life year saved for cervical cancer mass screening over no screening was $40,604. This result was very sensitive to changes in the screening charge and less sensitive to changes in incidence. The cost-effectiveness ratio was inversely related to incidence. If the incidence rate became 85% of the current figure in 2015, the cost-effectiveness ratio would be $48,176.
Authors' conclusions The cost-effectiveness ratio of cervical cancer screening was estimated to be $40,604. This was within the range of figures reported for other cancer screening programmes.
CRD COMMENTARY - Selection of comparators A justification was given for the comparator used, namely evidence that mortality was greatly reduced in areas with high coverage rates. You, as a user of the database, should decide if this is the case in your own setting.
Validity of estimate of measure of benefit The authors did not state that a systematic review of the literature had been undertaken. The methods and conduct of the review were not satisfactorily reported and effectiveness estimates were combined using narrative methods. The estimation of benefits was obtained directly from the effectiveness analysis. This choice of estimate was justified.
Validity of estimate of costs For the cost perspective adopted, all relevant categories of costs were included in the analysis. The analysis did not, however, include the cost of informal care, which would be relevant if more inclusive costing were undertaken. The cost-effectiveness of the intervention therapy may therefore have been overestimated. Costs and quantities were reported separately which increases the generalisability of the results. No sensitivity analysis of quantities was conducted which may limit the interpretability of the study findings. A sensitivity analysis of prices was conducted. Charges were used to proxy prices which tends to limit generalisability. The price year was not reported.
Other issues The authors did make appropriate comparisons of their findings with those from other studies although the issue of generalisability to other settings was not addressed. The authors did not present their results selectively. The study examined asymptomatic women aged 30 years for a 40-year period and this was reflected in the authors' conclusions.
Implications of the study Future studies should examine and compare the cost-effectiveness of other screening intervals (for example every other year) for cervical cancer.
Source of funding Supported in part by the Grant-in-Aid for Cancer Research (6-20) from the Ministry of Health and Welfare and in part by the Grant-in-Aid for Cancer Research from the Kurokawa Toshio Foundation.
Bibliographic details Matsunaga G, Tsuji I, Sato S, Fukao A, Hisamichi S, Yajima A. Cost-effective analysis of mass screening for cervical cancer in Japan. Journal of Epidemiology 1997; 7(3): 135-141 Indexing Status Subject indexing assigned by NLM MeSH Adult; Carcinoma in Situ /economics /epidemiology /prevention & Cohort Studies; Computer Simulation; Cost-Benefit Analysis; Female; Humans; Japan /epidemiology; Mass Screening /economics; Uterine Cervical Neoplasms /economics /epidemiology /prevention & Vaginal Smears /economics; control; control AccessionNumber 21998006108 Date bibliographic record published 31/10/2000 Date abstract record published 31/10/2000 |
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