Enhancing the rational use of antimalarials: The costeffectiveness of rapid immunochromatographic di

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Enhancing the rational use of antimalarials The
cost-effectiveness of rapid immunochromatographic
dipsticks in sub-Saharan Africa
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Malaria Diagnosis

• Current practice presumptive treatment
  (WHO,1999)
• ACTs are expensive
• Misdiagnosis
• Rapid dipstick tests are being developed for
  simple diagnosis
• WHO (1996) IMCI Information Package

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Study Questions

• At what levels of malaria prevalence is dipstick
  diagnosis cost-effective?
• How much should we be willing to pay for further
  information about model parameters before making
  a decision?

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Simple decision tree model
Sensitivity Specificity PT 100
0 0 100 Dip 86-94 6-14 72-99 1-28
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Probabilistic sensitivity analysis

• Uncertainty around most parameters represented by
  lognormal and beta distributions
• Incremental cost-effectiveness ratios (ICERs)
  calculated probabilistically using Monte-Carlo
  simulation
• ICERs converted to net-benefit
• Net Benefit Effects ? Costs
• The ceiling ratio (?) is US 150 per DALY averted
  (WHO, 1996)
• WHO (1996) Report of the Ad Hoc Committee on
  Health Research Relating to Future Investment
  Options

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Probability Cost-EffectiveCeiling Ratio
150/DALY averted
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Incremental Net-benefit
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Calculation of EVPICeiling Ratio 150/DALY
averted
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EVPI according to prevalence
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Discussion

• Cost-effectiveness most sensitive to
• Epidemiological setting
• Cost and accuracy of dipsticks
• Probability patients return for treatment
• Further benefits
• Reduce drug pressure and development of drug
  resistance
• Encourage use of treatment facilities
• Epidemiological surveillance

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Limitations of the model

• Assumes that health workers and patients trust
  and follow dipstick results
• False positive diagnoses are not well defined
• Does not consider private sector
• Not applicable in areas where microscopy is
  currently in use
• EVPI depends on number of variables you include
  in your model

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Further work

• Conduct a EVSI analysis to determine which
  parameters warrant further testing
• Consider parasite density, immunity, and health
  worker behaviour
• Determine affordability of dipsticks at a
  national level
• Predict impact on drug resistance

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Acknowledgements

• Chris Whitty
• Sarah Staedke
• Shunmay Yeung
• Andrew Briggs
• Funders UK Department for International
  Development, LSHTM Health Economics and Financing
  Programme