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Indoor Residual Spraying for Preventing Malaria in Settings with Low or No Net Coverage: A Systematic Review
62 Pages Posted: 16 Aug 2023
More...Abstract
Background: Malaria presents a significant public health burden globally. Substantial progress has been made with vector control initiatives such as residual insecticide surface treatment and insecticide treated nets. The objective of this systematic review was to examine the effectiveness of indoor residual spraying (IRS) for preventing malaria in areas with no or low coverage of nets.
Methods: We searched several databases, conference proceedings and organisations for published and unpublished studies investigating the effectiveness of residual insecticide surface treatment for malaria. Studies with moderate or high coverage of nets were excluded. Risk of bias was assessed using the Cochrane Risk of Bias assessment tool for cluster-randomised controlled trials and Risk of Bias In Non-randomised Studies of Intervention (ROBINS-I) tool. The reported outcomes were malaria incidence, malaria prevalence, anaemia prevalence, and all-cause mortality. Pairwise meta-analysis was conducted for the four outcomes and results have been presented for each age group. Results from randomised controlled trials and non-randomised studies were analysed separately. GRADE processes were followed to establish the certainty of the evidence and evidence profiles created.
Results: There was a total of 16 reports included in the systematic review, which represented nine unique studies. Of these, five were cluster-randomised controlled trials, one was a quasi-experimental study, and three were controlled before and after studies.In clusters that receive IRS, the evidence is very uncertain about the effect of IRS on malaria incidence and malaria prevalence in all ages and children, as well as all-cause mortality in all ages and in children under five years. In clusters that receive IRS, the evidence suggests that IRS does not reduce malaria prevalence in children under six years. Study settings and follow-up time varied widely between studies and therefore these results may depend on study setting.
Interpretation: There is very low certainty in the evidence for the impact of IRS on malaria outcomes in settings where there is no or very low net coverage. The certainty of this evidence was downgraded due to risk of bias, imprecision and/or inconsistency. Poor reporting of primary evidence was a major obstacle to understanding differences between important subgroups.
Registration: PROSPERO, ID 293194.
Funding: This work is funded by the World Health Organisation, APW202838570.
Declaration of Interest: The authors declare no other conflicting interests.
Keywords: Indoor residual spraying, malaria, systematic review, meta-analysis
Suggested Citation: Suggested Citation