The impact of community-delivered models of malaria control and elimination: a systematic review

Abstract

Background: Community-delivered models have been widely used to reduce the burden of malaria. This review aimed to explore different community-delivered models and their relative effectiveness in terms of coverage and malaria-metric outcomes in order to inform the design and implementation of Community Health Worker (CHW) programmes for malaria control and elimination.

Methods: A systematic review of studies investigating the impact of community-delivered models on coverage and malaria-metric (parasitaemia and hyperparasitaemia, malaria case and mortality, anaemia, and fever) outcomes compared to non- community-delivered models was undertaken by searching in five databases of published papers and grey literature databases. Data were extracted from studies meeting inclusion and quality criteria (assessed using relevant tools for the study design) by two independent authors. Meta-analyses were performed where there was sufficient homogeneity in effect and stratified by community-delivered models to assess the impact of each model on coverage and malaria-metric outcomes.

Results: 28 studies were included from 7042 records identified. The majority of studies (25/28) were performed in high transmission settings in Africa and there was heterogeneity in the type of, and interventions delivered as part of the community-delivered models. Compared to non- community-delivered models, community-delivered models increased coverage of actual bed net usage (Relative Risk (RR) = 1.64 95% CI 1.39, 1.95), intermittent preventive treatment in pregnancy (RR = 1.36 95% CI 1.29, 1.44) and appropriate and timely treatment of febrile children, and improved malaria-metric outcomes such as malaria mortality (RR = 0.58 95% CI 0.52, 0.65). However, the considerable heterogeneity was found in the impact of community-delivered models in reducing, parasitaemia and hyperparasitaemia prevalence, anaemia incidence, fever prevalence and malaria caseload. Statistical comparisons of different community-delivered models were not undertaken due to the heterogeneity of the included studies in terms of method and interventions provided.

Conclusion: Overall, the community-delivered model is effective in improving the coverage of malaria interventions and reducing malaria-associated mortality. The heterogeneity of the community-delivered models and their impact on malaria-metric indices suggests that evidence for context-specific solutions is required. In particular, community-delivered models for malaria elimination, integrated with services for other common primary health problems, are yet to be evaluated.

Keywords: Community health worker; Community-delivered model; Coverage; Malaria; Malaria-metric outcomes.

Fig. 1

PRISMA 2009 flow diagram [55]. *Excluded papers with reasons are available in Additional file 4

Fig. 2

Forest plot showing the association between use of CHW and coverage of insecticide treated bed net ownership and use. Plot shows risk ratios (RR), 95% confidence intervals (95% CI) and inverse variance study weights (% weight). Pooled results were calculated by fixed-effects (I-squared ≤ 30%) or random-effects (I-squared = 31% to ≤ 75%). Estimates were calculated from data in the papers. ITN ownership is defined as a household with at least one ITN, ITN use as ITN use (the previous night) by anyone and ITN use (the previous night) by under-5 children. Please note: results were not pooled in meta-analysis across different community-delivered models quantifying the effect of community-delivered models on ITN ownership or ITN use (the previous night) by under-5 children due to the high degree of heterogeneity (I-squared = 88.6% and 93.2%, respectively)

Fig. 3

Forest plot showing inverse variance meta-analysis of the effect of CHW on IPT in pregnancy (2 doses) coverage; random effect analysis of the association between use of CHW, and appropriate and timely (treatment within 24 h after onset of fever) treatment for fever on under-5 children. Plot shows risk ratios (RR), 95% confidence intervals (95% CI) and inverse variance study weights (% weight). Estimates were calculated from data in the papers. Please note: due to high heterogeneity results were not pooled across studies quantifying the effect of community-delivered models on appropriate treatment for fever on under-5 children and timely treatment for fever on under-5 children (I-squared = 96.9% and = 93.3%, respectively)

Fig. 4

Random effect analysis of the association between use of CHW and impact on parasitaemia and hyperparasitaemia. Plot shows risk ratios (RR) and 95% confidence intervals (95% CI). Estimates were calculated from data in the papers. Parasitaemia was defined as presence of any malaria parasite species [40, 41, 43, 48], or P. falciparum [39] by microscopy. Hyperparasitaemia was defined as parasite density 7000/μl [34], parasitaemia 5000/μl and over [41] and more than or equal to 2000 asexual forms of P. falciparum per mm [40] in the blood detected by microscopy. Due to high heterogeneity results were not pooled across studies quantifying the effect of community-delivered models on parasitaemia or hyperparasitaemia (I-squared = 93.4% and 87.5% respectively)

Fig. 5

Forest plot showing the impact of CHW on malaria clinical cases and malaria mortality. Plot shows risk ratios (RR), 95% confidence intervals (95% CI) and inverse variance study weights (% weight). Estimates were calculated from data in the papers. Malaria cases are confirmed by parasitological test [, , –44, 46, 47] and presumptive clinical diagnosis [45]. Please note: due to high heterogeneity results were not pooled across studies quantifying the effect of community-delivered models on clinical malaria cases (I-squared = 99.9%)

Fig. 6

Forest plot showing the impact of CHW on anaemia incidence and fever prevalence by random effect analysis. Plot shows risk ratios (RR) and 95% confidence intervals (95% CI). Estimates were calculated from data in the papers. Definitions: Anaemia is defined as Hb < 8.0 g/dl [–49] or haematocrit ≤ 24% [39]; Fever was defined as body temperature more than 37.5 °C [28, 30, 38, 39, 41, 48, 49] or reported fever cases [27, 56]. Studies investigating fever included women who had fever since delivery of last child [56]; fever plus parasitaemia [41], fever prevalence within last 1 month [30, 39, 48, 49] and last 2 weeks [27, 28] in general population; and fever prevalence [28] in under 5 children [38]. Please note: due to high heterogeneity results were not pooled across studies quantifying the effect of community-delivered models on risk of anaemia or fever (I-squared = 91.9% and 80.9%, respectively)