When is confirmed malaria diagnosis cost-effective?

22 July 2004

Barnish, Bates, and Iboro recently highlighted the need for improved malaria diagnostics and called for economic evaluation to determine the best approach to using them alongside treatment with artemisinin-based combination therapies (ACTs)[1]. We have developed mathematical models that address these questions in a range of transmission settings, building on published work on the cost-effectiveness of ACTs[2].

The factors determining cost-effectiveness include the prevalence and types of malaria, the cost of tests relative to subsequent treatment costs for patients diagnosed “positive” and “negative”, the community or health care setting [3,4] and long-term impact on drug resistance[2].

In low transmission settings, where most fevers are not caused by malaria and asymptomatic parasitemia is uncommon, using precious ACTs without accurate diagnosis is wasteful. Current research by Morel et al. suggests that rapid diagnostic tests (RDTs) are likely to be cost- effective where slide positivity is quite low (assuming RDTs cost US$0.55 -$1.10 and ACTs cost US$1.50 – 2.88)[5]. Where non-falciparum malaria is common, more expensive RDTs which can differentiate parasite species should be considered.

High transmission settings are more complex. Although it is rarely used, good quality microscopy should be cost-effective where malaria is frequently diagnosed. Microscopy may be preferable to RDTs because it allows parasitemia to be quantified, and RDTs detect very low levels of parasitaemia which may not be clinically significant in high transmission areas. Better information is needed on the fate of those diagnosed “malaria negative”.

We are currently refining the models for economic evaluation of ACTs to take into account a wider range of diagnostic options, the implications of imperfect implementation of ACTs, and the impact on drug resistance. ACTs are an order of magnitude more costly than chloroquine or SP monotherapy and issues of targeting and diagnostics are critical. However, the choice of treatment protocol must be evidence based, taking into account the costs and consequences of accurate and inaccurate diagnosis and the continued use of ineffective drugs.

References

1. Barnish G, Bates I, Iboro J. Newer Drug Combinations for Malaria: May be impractical unless diagnostic accuracy can be improved. BMJ 2004;328:1511-2.

2. Coleman PG, Morel CM, Shillcutt SD, Goodman CA, Mills AJ. A threshold analysis of the cost-effectiveness of artemisinin-based combination therapies in sub-Saharan Africa. American Journal of Tropical Medicine and Hygiene 2004;Forthcoming.

3. Mayxay M, Newton PN, Yeung S, Pongvongsa T, Phompida S, Phetsouvanh R. Short communication: An assessment of the use of malaria rapid tests by village health volunteers in rural Laos. Trop Med Int Health 2004;9(3):325-9.

4. Pang LW. Economic advantage of a community-based malaria management program in the Brazilian Amazon. American Journal of Tropical Medicine and Hygiene 2001;65(6):883-6.

5. Morel C, Shillcutt S, Coleman P, Goodman C, Mills A. The Economics of Diagnosis: The Case of Dipsticks for malaria diagnosis prior to treatment with artemisinin-based combination therapy. to be submitted.

Competing interests: None declared

Competing interests: None declared

Paul G Coleman, Honorary Senior Lecturer

Catherine Goodman, Anne Mills, Chantal Morel, Sam Shillcutt, Shun May Yeung

London School of Hygiene and Tropical Medicine

Click to like: