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Genotype Resistance Index (GRI) and Genotype Failure Index (GFI) for Epidemiologic Studies of Drug Resistant Plasmodium falciparum

Description

Certain genotypes of Plasmodium falciparum are associated with drug resistance, which in turn is associated with therapeutic failure in patients. The Genotype Resistance and Failure Indices (GRI, GFI) can be helpful in epidemiologic studies of drug resistance in a population. The change in drug resistance and therapeutic failure should change with changes in the prevalence of the molecular marker in malarial isolates.


 

Parameters:

(1) prevalence of molecular marker in isolates

(2) prevalence of drug resistance in parasite

(3) prevalence of therapeutic failure

 

genotype resistance index GRI =

= (prevalence of molecular marker) / (prevalence of drug resistance in parasite)

 

genotype failure index GFI =

= (prevalence of molecular marker) / (prevalence of therapeutic failure in population)

 

If these indices are relatively constant then when doing an epidemiologic study:

 

predicted prevalence of drug resistance in malaria isolates =

= (prevalence of molecular marker) / (GRI)

 

predicted prevalence of therapeutic failure in the population =

= (prevalence of molecular marker) / (GFI)

 

which are just rearrangements of the previous equations.

 


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Specialty

ICD-10