Summary of findings 1. Topical repellents versus placebo or no treatment in adults and children living in malaria‐endemic areas.
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Patient or population: adults and children in malaria‐endemic areas Setting: malaria‐endemic areas (November 1991 to June 2016; Bolivia, Cambodia, Ecuador, Laos PDR, Myanmar, Pakistan, Peru, Tanzania, Thailand) Intervention: topical repellents Comparison: placebo or no treatment | ||||||
| Outcome | Anticipated absolute effects (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with placebo or no treatment | Risk difference with topical repellents | |||||
| Malaria infection incidence alone (Follow‐up: mean 6 months) | 37 per 1000 | 9 fewer per 1000 (16 fewer to 1 more) | Rate ratio 0.76 (0.56 to 1.02) | 12,813 (2 cRCTs, 1 RCT) | ⨁⨁◯◯ Lowa,b | Topical repellents may make little or no difference to the incidence of P falciparum infection. |
| Malaria case incidence alone (Follow‐up: mean 12 months) | 22 per 1000 | 7 fewer per 1000 (15 fewer to 8 more) | Rate ratio 0.66 (0.32 to 1.36) | 48,838 (1 cRCT) | ⨁⨁◯◯ Lowc,d | Topical repellents may make little or no difference to P falciparum clinical case incidence |
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Malaria case and infection incidence together (Follow‐up: mean 7 months) |
24 per 1000 | 6 fewer per 1000 (10 fewer to 0 fewer) | Rate ratio 0.74 (0.56 to 0.98) | 61,651 (3 cRCTs, 1 RCT) | ⨁⨁◯◯ Lowb,e | Topical repellents may slightly reduce P falciparum infection and clinical case incidence when both outcomes are pooled |
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Adverse events Assessed with self‐reported questionnaires and in‐person interviews (Follow‐up: mean 13 months) |
A total of 283 adverse events (0.6%) were observed among participants who received topical repellents. | 47,515 (6 cRCTs, 1 RCT) | ‐ | Topical repellents are considered safe | ||
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Malaria prevalence (Follow‐up: mean 13 months) |
13 per 1000 | 2 fewer per 1000 (4 fewer to 0 fewer) | Odds ratio 0.81 (0.67 to 0.97) | 55,366 (3 cRCTs, 1 RCT) | ⨁⨁◯◯ Lowb,f | Topical repellents may slightly reduce P falciparum prevalence |
Abbreviations: CI: confidence interval; cRCT: cluster‐randomized controlled trial; RCT: randomized controlled trial.
The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). The denominator in the malaria incidence outcomes is person‐years, and people in the prevalence outcome.
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect
aDowngraded 1 level due to risk of bias associated with the procedures used to randomize participants, conceal allocation, and imbalances in the allocation groups. bDowngraded 1 level due to indirectness associated with the inclusion of only pregnant women in one study. cDowngraded 1 level due to risk of bias associated with imbalances in the allocation groups and the lack of placebo in controls. dDowngraded 1 level due to imprecision, as 95% CIs include a relevant reduction in malaria incidence and no effect. eDowngraded 1 level due to risk of bias associated with procedures used to conceal allocation, imbalances in the allocation groups, and a large proportion of losses to follow‐up (16.6%) in one study. fDowngraded 1 level due to risk of bias associated with the step‐wedged design and the lack of placebo in the control group of two studies, issues in the procedures used to blind study participants, and imbalances in allocation groups.