Community-based interventions for the prevention and control of non-helminthic neglected tropical diseases (NTDs)

Methodological quality of the review: Low confidence

Author: Das JK, Salam RA, Ashad A, Maredia H, Bhutta ZA

Geographical coverage: Worldwide

Sector: Non-helminthic NTDs

Sub-sector: Prevention, community-based interventions

Equity focus: None specified

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Qualitative synthesis

Background:

Non-helminthic infections are a group of viral (dengue fever), protozoal (African trypanosomiasis, chagas and leishmaniasis) and bacterial (buruli ulcer, leprosy and trachoma) diseases endemic amongst the poorest populations living in tropical and sub-tropical regions. These infections can lead to burdensome health consequences which are accountable for severe economic costs including blindness due to trachoma and disfigurement from leishmaniasis, leprosy and buruli ulcer.

Objectives:

Authors aimed to analyse the effectiveness of community-based intervention (CBI) for the prevention and control of non-helminthic neglected tropical diseases (NTDs), including dengue, trypanosomiasis, chagas, leishmaniasis, buruli ulcer, leprosy and trachoma.

Main findings:

In total, 62 studies were included in the review. 21 were randomised controlled trials (RCTs) and 41 were before-and-after studies. Of these 62 studies, 17 studies were on dengue, four on chagas, 12 on leishmaniasis, six on leprosy and 23 on trachoma prevention and control.

For the 21 RCTs included in this review, randomisation was adequate in all 21 studies, allocation was concealed in seven and adequate sequence generation was done in ten, while studies provided insufficient information on selective reporting which limited us from making any judgment.

Included studies mainly focused on community-based vector control measures such as insecticide spraying and insecticide treated nets (ITNs) for dengue, chagas and leishmaniasis; mass drug administration (MDA) for the prevention and treatment of leprosy and trachoma, and the SAFE strategy for trachoma.

All the studies for dengue and chagas targeted the general population, while two studies for leishmaniasis, one for leprosy and five for trachoma targeted children less than 15 years of age.

Pooled analysis suggested that CBI for dengue preventative measures, including the use of ITNs and curtains, significantly reduced dengue-positive serotatus by 70% (RR: 0.30, 95% CI: 0.23, 0.38) while community education alone did not have a significant effect.

Insecticide spraying and aerosols significantly reduced the house index by 10% (RR: 0.90, 95% CI: 0.86, 0.95). For chagas, CBI including insecticide spraying and housing improvements had a significant impact with a 68% reduction in the domiciliary infestation rate (RR: 0.78, 95% CI: 0.61, 0.98), but did not show any significant impact on the peri-domiciliary infestation rate.

For leishmaniasis, CBI including ITNs and curtains, along with community education, significantly reduced the incidence of cutaneous leishmaniasis by 58% (RR: 0.42, 95% CI: 0.36,0.49). Treatment with thermotherapy and radiofrequency resulted in a significant 8% (RR: 0.92, 95% CI: 0.88, 0.96) reduction in cure rates of cutaneous leishmaniasis, while interventions including surveillance, elimination of dogs, dog collars and ITNs had a non-significant impact on the incidence of visceral leishmaniasis.

For leprosy, treatment with MDA or rifampicin, together with community education, resulted in a 68% reduction in the incidence of leprosy (RR: 0.32, 95% CI: 0.30, 0.34) and an 11% improvement in detection rate (RR: 1.11, 95% CI:1.02, 1.21). CBI for trachoma treatment with the SAFE strategy and azithromycin, along with community education on hygiene, had a significant reduction of 76% (RR: 0.24, 95% CI:0.21, 0.26) and 33% (RR: 0.67, 95% CI: 0.64,0.69) in active trachoma among all age groups and children respectively.

Chlamydia trachomatic infections also reduced by 71% (RR: 0.29, 95% CI: 0.27, 0.32) and 79% (RR: 0.21, 95% CI: 0.18, 0.24) among all age groups and children respectively. Sub-group analysis for the relative effectiveness of preventive and therapeutic drug administration, and for the evidences from RCT and pre-post studies, did not show any major differences.

Qualitative studies supported that community-delivered interventions have the potential to achieve wider coverage and sustained community acceptance, with the combination approach having a more rapid and sustainable effect compared to individual interventions.

Methodology:

Methods used to conduct this review were reported in another article, which was used to extract data on methodology. Studies focused on evaluating the effectiveness of CBI targeting 14 major NTDs were included in this review (leishmaniasis, human African trypanosomiasis, chagas disease, dengue, trachoma, leprosy, buruli ulcer, and the helminthes including hookworm, ascariasis, trichuriasis, LF, onchocerciasis, dracunculiasis and schistosomiasis); malaria; TB and HIV/AIDS compared to routine healthcare delivery.

Authors considered all available existing randomised, quasi-randomised, and before-and-after studies measuring the impact of CBI to prevent and control non-helminthic NTDs. In addition, authors also considered the inclusion of less rigorous studies such as observational and descriptive studies to understand the context within which they were implemented.  Studies were included if intervention was delivered within community settings and if reported outcomes were relevant to the diseases under review.

Authors conducted a search on the following databases: PUBMED, Cochrane Libraries, EMBASE and World Health Organisation (WHO) regional databases to identify both published and unpublished studies. Authors also hand-searched references of included studies. Screening of included studies and data extraction was conducted by two reviewers, however it’s not clear if this was conducted independently. Two reviewers independently assessed the risk of bias of each study using the Cochrane risk of bias assessment criteria.

Authors conducted meta-analyses using RR for categorical variables and SMD for continuous variables between experimental and control groups with 95% CIs. Mantel-Haenszel pooled RR and corresponding 95% CIs were reported when there was no evidence of heterogeneity. The DerSimonian and Laird-pooled RR and corresponding 95% CIs were reported where there was an unexplained heterogeneity. Heterogeneity was quantified by Chi² and I² tests. In situations of high heterogeneity, a sensitivity analysis was performed and, if possible, sub-group analyses were performed.

Authors also attempted to qualitatively synthesise the findings reported in the included studies for other pragmatic parameters.

Applicability/external validity:

Authors did not discuss the applicability/external validity of included studies. Authors noted how all the studies for dengue and chagas targeted general population, while two studies for leishmaniasis, one for leprosy and five from trachoma targeted children less than 15 years of age.

Geographic focus:

Authors included studies from several countries including: Argentina, Cambodia, Thailand, Philippines, West Indies, China, Bangkok, Taiwan, Vietnam, Indonesia, Columbia, Puerto Rico, Mexico, Cuba, Haiti, Paraguay, Turkey, Brazil, Syria, Iran, India, Nepal, Afghanistan, Nigeria, Yemen, Bangladesh, Ghana, Ethiopia, Zambia, Australia, Mali, Niger, The Gambia and Egypt. However, authors did not mention how applicable results of the review are to low- and middle-income countries.

Summary of quality assessment:

Overall, there is low confidence in the conclusions about the effects of this study as important limitations were identified. Authors did not conduct a thorough search of the literature to ensure that relevant studies were not omitted in the review. Although authors searched for published and unpublished studies, authors did not avoid language bias, which may imply the presence of publication bias within the review. It is not clear from the review if characteristics of included studies were reliably reported, nor if screening of studies were conducted by two reviewers independently. In addition, potential limitations of the review were not reported/acknowledged by review authors.