Meta-analysis: accuracy of rapid tests for malaria in travelers returning from endemic areas.
BACKGROUND
Microscopic diagnosis of malaria is unreliable outside specialized centers. Rapid tests have become available in recent years, but their accuracy has not been assessed systematically.


OBJECTIVE
To determine the accuracy of rapid diagnostic tests for ruling out malaria in nonimmune travelers returning from malaria-endemic areas.


METHODS
The authors searched MEDLINE, EMBASE, CAB Health, and CINAHL (1988 to September 2004); hand-searched conference proceedings; checked reference lists; and contacted experts and manufacturers.


METHODS
Diagnostic accuracy studies in nonimmune individuals with suspected malaria were included if they compared rapid tests with expert microscopic examination or polymerase chain reaction tests.


METHODS
Data on study and patient characteristics and results were extracted in duplicate. The main outcome was the likelihood ratio for a negative test result (negative likelihood ratio) for Plasmodium falciparum malaria. Likelihood ratios were combined by using random-effects meta-analysis, stratified by the antigen targeted (histidine-rich protein-2 [HRP-2] or parasite lactate dehydrogenase [LDH]) and by test generation. Nomograms of post-test probabilities were constructed.


RESULTS
The authors included 21 studies and 5747 individuals. For P. falciparum, HRP-2-based tests were more accurate than parasite LDH-based tests: Negative likelihood ratios were 0.08 and 0.13, respectively (P = 0.019 for difference). Three-band HRP-2 tests had similar negative likelihood ratios but higher positive likelihood ratios compared with 2-band tests (34.7 vs. 98.5; P = 0.003). For P. vivax, negative likelihood ratios tended to be closer to 1.0 for HRP-2-based tests than for parasite LDH-based tests (0.24 vs. 0.13; P = 0.22), but analyses were based on a few heterogeneous studies. Negative likelihood ratios for the diagnosis of P. malariae or P. ovale were close to 1.0 for both types of tests. In febrile travelers returning from sub-Saharan Africa, the typical probability of P. falciparum malaria is estimated at 1.1% (95% CI, 0.6% to 1.9%) after a negative 3-band HRP-2 test result and 97% (CI, 92% to 99%) after a positive test result.


CONCLUSIONS
Few studies evaluated 3-band HRP-2 tests. The evidence is also limited for species other than P. falciparum because of the few available studies and their more heterogeneous results. Further studies are needed to determine whether the use of rapid diagnostic tests improves outcomes in returning travelers with suspected malaria.


CONCLUSIONS
Rapid malaria tests may be a useful diagnostic adjunct to microscopy in centers without major expertise in tropical medicine. Initial decisions on treatment initiation and choice of antimalarial drugs can be based on travel history and post-test probabilities after rapid testing. Expert microscopy is still required for species identification and confirmation.
Marx
Arthur
A
University of Berne and MediX General Practice Network, Berne, Switzerland.
Pewsner
Daniel
D
Egger
Matthias
M
Nüesch
Reto
R
Bucher
Heiner C
HC
Genton
Blaise
B
Hatz
Christoph
C
Jüni
Peter
P
D000446:Aldehyde-Lyases / Q000097:blood; D019353:Endemic Diseases; D005189:False Positive Reactions; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D016013:Likelihood Functions; D008288:Malaria / Q000175:diagnosis* / Q000453:epidemiology; D016778:Malaria, Falciparum / Q000175:diagnosis / Q000453:epidemiology; D010274:Parasitology / Q000379:methods*; D011506:Proteins / Q000032:analysis; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D012680:Sensitivity and Specificity; D014195:Travel; D014481:United States / Q000453:epidemiology; D000099053:Histidine-Rich Glycoprotein
D011506:Proteins; D011933:Reagent Kits, Diagnostic; D000099053:Histidine-Rich Glycoprotein; D007770:L-Lactate Dehydrogenase; D000446:Aldehyde-Lyases