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WWARN Clinical Trials Publication Library

A comprehensive compilation of all antimalarial clinical efficacy trials conducted and published since 1946. 

Between 1946 to 2020 a total of 1,278 published clinical efficacy studies were identified from over 50,000 screened articles, enrolling a total of 352,933 patients.

See attachments on the right-hand side to download a WWARN publication library of the references and the key parameters of these studies. The library is updated every six months.

The highlights are detailed below:

Descriptive characteristics

- Overall 997 (76%) of studies assessed P. falciparum, 290 P. vivax, 80 both, and 51 other Plasmodium species.
- Of the 1,194 studies where age was described, 657 (55%) enrolled children under five years and 61 (5%) enrolled pregnant women. 
- Of 1,168 studies with information on study design, 635 (54%) of studies were randomised and 129 (11%) were blinded.

Temporal trends 

Figure 1 Number of publications per year by region. The number of studies published per year increased over time, with 70% of P. falciparum and 82% of P. vivax studies published after 2000. Most of this increase was due to an increasing number of studies in Africa, especially for P. falciparum.

Spatial trends 

 

Figure 2 Map of study sites. The majority of studies have been conducted in Africa (44%) or Asia (44%), with 55 multi-centred. The most common study locations were in Thailand, Nigeria, India and Kenya for P. falciparum, and Thailand, India, Brazil and Indonesia for P. vivax. In the last five years there has been a marked increase of studies in African centres for P. falciparum.

Treatments 

Figure 3 The most common treatment regimens studied. Numbers represent treatment arms. Left panel for P. falciparum and right panel for P. vivax. The most common drugs tested were artemether-lumefantrine (14% treatment arms) for P. falciparum, and chloroquine +/– primaquine (65% treatment arms) for P. vivax. 

Figure 4 Number of treatment arms per year by drug type. The left four show P. falciparum and the right four show P. vivax. WHO-recommended ACTs were tested in 40% of P. falciparum arms and 11% of P. vivax arms. There has been a significant increase in the number of P. falciparum studies testing ACTs over time, especially in Africa where in the last five years 78% of treatment arms tested an ACT.

Conclusions

  • The volume of research on antimalarial therapy has increased substantially over the last 50 years, the predominant increase attributable to new studies conducted in Africa for P. falciparum, and an increase in P. vivax studies.
  • Significant knowledge gaps remain: in some heavily affected countries, in non-Pf species, and in at-risk populations such as pregnant women.
  • There is a relatively long delay to publication, which undermines the availability of contemporaneous evidence for policymakers.