Commons RJ, et al. - Via performing a systematic review and meta-analysis, researchers investigated the effect of chloroquine dose and the addition of primaquine on the risk of recurrent vivax malaria across different settings. They identified frequent under-dosing of chloroquine in the treatment of vivax malaria. In children younger than 5 years, a substantial reduction in the risk of early recurrence could be achieved by increasing the recommended dose to 30 mg/kg when primaquine is not given. Findings suggest a high efficacy of radical cure with primaquine in preventing early recurrence. It may also improve blood schizontocidal efficacy against chloroquine-resistant P vivax.

Methods

• Researchers performed a systematic review in MEDLINE, Web of Science, Embase, and Cochrane Database of Systematic Reviews to identify P vivax clinical trials published between Jan 1, 2000, and March 22, 2017.
• They invited principal investigators to share individual patient data, which were pooled using standardised methods.
• The roles of chloroquine dose and primaquine use on rate of recurrence between day 7 and day 42 (primary outcome) were investigated via Cox regression analyses with random effects for study site.

Results

• Researchers identified 134 chloroquine studies; of these, 37 studies (from 17 countries) and 5240 patients were included.
• Chloroquine alone was used in 2990 patients for treatment; a dose below the target 25 mg/kg was administered to 1041 (34·8%) patients.
• By day 42, recurrence risk of 32·4% was noted (95% CI 29·8–35·1).
• After controlling for confounders, the rate of recurrence overall (adjusted hazard ratio [AHR] 0·82, 95% CI 0·69–0·97; p=0·021) and in children younger than 5 years (0·59, 0·41–0·86; p=0·0058) was reduced with a 5 mg/kg higher chloroquine dose.
• Primaquine addition led to reduction in the risk of recurrence to 4·9% (95% CI 3·1–7·7) by day 42, which is lower than with chloroquine alone (AHR 0·10, 0·05–0·17; p<0·0001).