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Cost effectiveness analysis of strategies to combat malaria in developing countries |
Morel C M, Lauer J A, Evans D B |
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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 Several preventive and treatment strategies for the control of malaria in sub-Saharan Africa were examined. The seven individual strategies considered were:
insecticide-treated bed nets (ITN);
indoor residual spraying (IRS);
case management with chloroquine (CQ);
case management with sulfadoxine-pyrimethamine (SP);
case management with non-artemisinin based (CQ-SP) combination treatment (Comb);
case management with artemisinin-based combination treatment (ACT); and
intermittent presumptive treatment with SP in pregnancy (IPTp).
The interventions were also considered in combination. Twenty individual and combination options were evaluated at three assumed coverage levels (50, 80 and 95% target levels). Thus, in total, 60 interventions were included.
Type of intervention Primary prevention and treatment.
Study population The study population comprised hypothetical cohorts of individuals at risk of malaria infection in two World Health Organization (WHO) epidemiological groups. One of the groups was Afr-E (predominantly Southern and Eastern Africa), defined as African countries with high child mortality (all causes) and very high adult mortality (all causes). The other group was Afr-D (predominantly Western Africa), defined as African countries with high child mortality and high adult mortality.
Setting The setting was the community. The economic study was carried out in Afr-E and Afr-D regions.
Dates to which data relate Most of the effectiveness data were derived from studies published between 1998 and 2003. Some costs and resource use data were derived from studies published in 2003 and 2005. The price year was 2000.
Source of effectiveness data The effectiveness evidence was derived from a synthesis of published studies and experts' opinions.
Modelling The authors stated that a state-transition model was used to project the population impact of the intervention scenarios. However, limited information on the model was reported. The time horizon of the analysis was 10 years.
Outcomes assessed in the review The outcomes estimated from the literature were clinical data that were used to populate the model. These consisted of data on current coverage (percentage of people at risk who are given drugs in the current situation), efficacy of the interventions, and the burden of malaria. Burden was measured in terms of disability-adjusted life-years (DALYs).
Study designs and other criteria for inclusion in the review It was unclear whether the primary estimates were derived from a systematic review of the literature or were identified selectively. Limited information on the design and characteristics of the primary studies was provided. Much of the data were estimated from WHO publications.
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 Number of primary studies included Approximately seven studies provided the data.
Methods of combining primary studies Investigation of differences between primary studies Results of the review In Afr-D, 23% of people at risk were given CQ, 3% SP, 0% CQ-SP, 0% ACT, 2% ITN, 0% IRS and 0% IPTp.
In Afr-E, 27% of people at risk were given CQ, 3% SP, 0% CQ-SP, 0% ACT, 2% ITN, 3% IRS and 0% IPTp.
Adherence was 65% with ITN, 100% with IRS, 40% with CQ, 90% with SP, 35% with CQ-SP, 40% with ACT and 80% with IPTp.
The baseline reduction in malaria incidence was 50% with both ITN and IRS, and 0% with CQ, SP, CQ-SP, ACT and IPTp.
The baseline reduction in case fatality (before patient adherence and parasite drug resistance were taken into account) was 20% with both ITN and IRS, 98% with CQ, SP, CQ-SP and ACT, and 5% with IPTp.
After considering treatment failures, the net effectiveness of the interventions was re-calculated. The reduction in case fatality was 20% with ITN and IRS, 27% with CQ, 44% with SP, 48% with CQ-SP, 63% with ACT and 3.4% with IPTp.
The burden of malaria was 19,088,877 DALYs in Afr-D and 17,680,061 DALYs in Afr-E.
Methods used to derive estimates of effectiveness The authors stated that some of their calculations were supported by experts' opinions. However, details on the use of such assumptions were not reported. Some data came from personal communications.
Estimates of effectiveness and key assumptions Initial resistance was 0.3 with CQ, 0.1 with SP, 0.1 with CQ-SP, 0.001 with ACT and 0.1 with IPTp.
The growth rate of resistance was 0.1 with CQ, 0.4 with SP, 0.1 with CQ-SP, 0.05 with ACT and 0.1 with IPTp.
Other assumptions were also made but no further details were given.
Measure of benefits used in the economic analysis The summary benefit measure was the expected number of DALYs. This was obtained using the decision model, but no information on the approach taken was provided.
Direct costs The perspective adopted in the study was not explicitly stated, but it might have been that of the national funding authority. The cost analysis included items such as salaries, capital equipment, drugs, storage, buildings, office supplies and furniture. These were derived from a review of the literature, supplemented by primary data from several countries. The distribution costs were calculated with a standard mark-up based on the average of free on board; cost, insurance, and freight; and additional trade-related distributional costs. The media costs were a substantial component of malaria control. The labour costs were estimated according to the educational level of the workers. The unit costs were not presented separately from the quantities of resources used, and a detailed breakdown of the cost items was not reported. The costs came from multiple sources, including effectiveness trials, data from the WHO-CHOICE database, existing literature and expert opinion. It was unclear whether discounting was performed but the annual costs were reported. The price year was 2000.
Statistical analysis of costs The costs appear to have been treated deterministically.
Indirect Costs The indirect costs do not appear to have been included.
Currency International US dollars (Int$).
Sensitivity analysis It was stated that sensitivity analyses were performed for age weights and discounting, but no further information was reported.
Estimated benefits used in the economic analysis Only non-dominated interventions were reported (more details on all 60 interventions were reported in the technical appendix).
The estimated DALYs averted in Afr-D (over no intervention) were:
7,771,018 with ACT with 80% coverage;
9,254,473 with ACT with 95% coverage;
12,972,791 with ITN plus ACT plus IPTp with 95% coverage; and
14,561,792 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
The estimated DALYs averted (over no intervention) in Afr-E were:
5,886,159 with ACT with 95% coverage;
9,138,452 with ITN plus ACT with 95% coverage;
10 721 678 with IRS plus ITN plus ACT with 95% coverage; and
10,729,154 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
Cost results Only non-dominated interventions were reported (more details on all 60 interventions were reported in the technical appendix).
The estimated costs in Afr-D were:
Int$72,386,626 with ACT with 80% coverage;
Int$95,609,717 with ACT with 95% coverage;
Int$315,546,119 with ITN plus ACT plus IPTp with 95% coverage; and
Int$467,673,321 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
The estimated costs in Afr-E were:
Int$73,000,256 with ACT with 95% coverage;
Int$254,755,715 with ITN plus ACT with 95% coverage;
Int$441,216,954 with IRS plus ITN plus ACT with 95% coverage; And
Int$442,342,075 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
Synthesis of costs and benefits Incremental cost-utility ratios were calculated to combine the costs and benefits of the alternative interventions.
The average cost per DALY averted (in comparison with no intervention) in Afr-D was:
Int$9 with ACT with 80% coverage;
Int$10 with ACT with 95% coverage;
Int$24 with ITN plus ACT plus IPTp with 95% coverage; and
Int$32 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
In comparison with no intervention, the incremental cost per DALY averted in Afr-E was:
Int$12 with ACT with 95% coverage;
Int$28 with ITN plus ACT with 95% coverage;
Int$41 with IRS plus ITN plus ACT with 95% coverage; and
Int$41 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
When comparing each intervention with the next less effective strategy, the incremental cost per DALY averted in Afr-D was:
Int$9 with ACT with 80% coverage;
Int$10 with ACT with 95% coverage;
Int$59 with ITN plus ACT plus IPTp with 95% coverage; and
Int$96 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
The other strategies were dominated by at least one of the reported alternatives.
When comparing each intervention with the next less effective strategy, the incremental cost per DALY averted in Afr-E was:
Int$12 with ACT with 95% coverage;
Int$56 with ITN plus ACT with 95% coverage;
Int$118 with IRS plus ITN plus ACT with 95% coverage; and
Int$151 with IRS plus ITN plus ACT plus IPTp with 95% coverage.
The other strategies were dominated by at least one of the reported alternatives.
Authors' conclusions High coverage with artemisinin-based combination treatments was the most cost-effective strategy for the control of malaria in most countries in sub-Saharan Africa.
CRD COMMENTARY - Selection of comparators The selection of the comparators appears to have been appropriate as all possible interventions were considered in the analysis. Several combinations were considered at three different coverage levels. You should decide whether they are valid comparators in your own setting.
Validity of estimate of measure of effectiveness The effectiveness evidence came from published sources. However, it was unclear whether the studies had been identified from a review of the literature. Further, no information on the conduct and method of the review was provided. The details and other characteristics of the primary studies were not described. Thus, it was difficult to assess the validity of the primary data. The role played by expert opinions was unclear. The issue of uncertainty in the clinical data was not investigated in the sensitivity analysis.
Validity of estimate of measure of benefit DALYs are a typical measure used to assess the benefits of interventions implemented in developed countries. The approach used to calculate the DALYs was not described clearly. The use of discounting was not reported. DALYs are comparable with the benefits of other health care interventions.
Validity of estimate of costs The perspective adopted in the study was not explicitly stated. A detailed breakdown of the cost items was not provided, and this limits the possibility of replicating the study in other settings. The source of the data was not reported for all items. The costs were treated deterministically and no sensitivity analyses were carried out. The price year was provided, which will facilitate reflation exercises in other time periods. Overall, there was limited information on the cost analysis.
Other issues The authors noted the differences between their study and published studies. In particular, the authors stressed the fact that this was the first study that had considered combinations of treatments rather than concurrent treatments. However, some consistency with previous publications was observed. The issue of the generalisability of the study results to other settings was not addressed, but the study referred to a wide geographic area. The authors noted some limitations of their study. For example, it was noted that the efficacy of some interventions was uncertain or depended on local factors.
Implications of the study The study results suggested that a much larger infusion of resources than those currently available is needed to make headway in the fight to roll back malaria. The current study supported the use of artemisinin-based combination treatments.
Source of funding This research was partially supported by the World Health Organization.
Bibliographic details Morel C M, Lauer J A, Evans D B. Cost effectiveness analysis of strategies to combat malaria in developing countries. BMJ 2005; 331: 1299-1302 Other publications of related interest Goodman CA, Coleman PG, Mills AJ. Cost-effectiveness of malaria control in sub-Saharan Africa. Lancet 1999;354:378-84.
Goodman CA, Minzava AE, Diamini SS, et al. Comparison of the cost and cost-effectiveness of insecticide-treated bednets and residual house-spraying in KwaZulu-Natal, South Africa. Trop Med Int Health 2001;6:280-95.
Coleman PG, Morel CM, Shillcutt SD, et al. A threshold analysis of the cost-effectiveness of artemisinin-based combination therapies in sub-Saharan Africa. Am J Trop Med Hyg 2004;71:196-204.
Indexing Status Subject indexing assigned by NLM MeSH Africa South of the Sahara /epidemiology; Antimalarials /economics /therapeutic use; Bedding and Linens /economics; Cost-Benefit Analysis; Delivery of Health Care /economics; Health Personnel /economics; Health Promotion /economics; Humans; Insecticides /economics; Malaria, Falciparum /economics /epidemiology /prevention & Mosquito Control /economics; Prevalence; Program Evaluation; control AccessionNumber 22005008470 Date bibliographic record published 31/03/2006 Date abstract record published 31/03/2006 |
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