Summary of findings for the main comparison. Topical repellents compared to placebo or no treatment for malaria prevention.
| Topical repellents compared to placebo or no treatment for malaria prevention | ||||||
| Patient or population: malaria prevention Setting: malaria‐endemic regions Intervention: topical repellents Comparison: placebo or no treatment | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | Number of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with Placebo or no treatment | Risk with Topical repellents | |||||
| Clinical malaria: P. falciparum | 39 per 1000 | 25 per 1000 (15 to 41) | RR 0.65 (0.40 to 1.07) | 4450 (3 studies) | ⊕⊝⊝⊝
VERY LOW1,2,3 Due to risk of bias, inconsistency and imprecision |
We do not know if topical repellents have an effect on malaria cases caused by P. falciparum. We have very little confidence in the effect estimate. The true effect is likely to be substantially different from the estimate of effect. |
| Parasitaemia: P. falciparum | 15 per 1000 | 12 per 1000 (9 to 17) | RR 0.84 (0.64 to 1.12) | 13,310 (4 studies) | ⊕⊕⊝⊝
LOW4,5 Due to risk of bias and imprecision |
Topical repellents may or may not have a protective effect against P. falciparum parasitaemia. Our confidence in the effect estimate is limited. The true effect may be substantially different from the estimation of the effect. |
| Clinical malaria: P. vivax | 36 per 1000 | 48 per 1000 (36 to 64) | RR 1.32 (0.99 to 1.76) | 3996 (2 studies) | ⊕⊕⊝⊝
LOW6,7 Due to risk of bias and imprecision |
Topical repellents may increase the number of clinical cases caused by P. vivax. Our confidence in the effect estimate is limited. The true effect may be substantially different from the estimation of the effect. |
| Parasitaemia: P. vivax | 18 per 1000 | 19 per 1000 (14 to 25) | RR 1.07 (0.80 to 1.41) | 9434 (3 studies) | ⊕⊕⊝⊝
LOW7,8 Due to risk of bias and imprecision |
Topical repellents may or may not have a protective effect against P. vivax parasitaemia Our confidence in the effect estimation is limited. The true effect may be substantially different from the estimation of the effect. |
| *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). Abbreviations: CI: confidence interval; RR: risk ratio; OR: odds ratio. | ||||||
| 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. | ||||||
1Downgraded by 1 for risk of bias: Sangoro 2014a used alternate allocation and reported a baseline imbalance; random sequence generation and allocation concealment were not described by Rowland 2004; and Sluydts 2016 did not have a placebo so the intervention was not blinded. 2Downgraded by 1 because of the large heterogeneity between the 3 trials. The I² statistic, which quantifies the proportion of the variation in the point estimates due to among‐study differences, was considered substantial at 50%. The subgroup analysis to some extent explained the heterogeneity but we do not believe that there is enough evidence to suggest there is a true subgroup effect given that there is no heterogeneity in the outcome parasitaemia caused by P. falciparum where studies with and without LLINs were also analysed. 3Downgraded by 1 for imprecision because the sample size is too small, the CIs are wide, the pooled effect (0.40 to 1.07) overlaps a risk ratio (RR) of 1.0 (no effect) and presents an estimate of effect ranging between beneficial and harmful. 4Downgraded by 1 for risk of bias: Hill 2007 used alternate allocation and reported a baseline imbalance; random sequence generation and allocation concealment were not described by McGready 2001. 5Downgraded by 1 for imprecision because the sample size is too small, the CIs are very wide, the pooled effect (0.62 to 1.12) overlaps a risk ratio (RR) of 1.0 (no effect) and presents an estimate of effect ranging between beneficial and harmful. 6Downgraded by 1 for risk of bias: random sequence generation and allocation concealment were not described by Rowland 2004; Sluydts 2016 was not placebo‐controlled and intervention was not blinded. 7Downgraded by 1 for imprecision because the CIs are very wide, the pooled effect (0.80 to 1.41) overlaps a risk ratio (RR) of 1.0 (no effect) and presents an estimate of effect ranging between beneficial and harmful. 8Downgraded by 1 for risk of bias: random sequence generation and allocation concealment were not described by McGready 2001.