LLINEUP Cluster Randomized Trial

Related studies:

LLINEUP2 Cluster Randomized Trial

Background: Long-lasting insecticidal nets (LLINs) have been shown to reduce malaria morbidity and mortality across a range of epidemiological settings, and the scale-up of nets is estimated to have been responsible for 69% of P. falciparum cases averted in Africa between 2000 and 2015. The World Health Organization (WHO) recommends universal coverage of populations at risk, defined as one net for every two people to achieve community benefits.

In Uganda, LLINs are the primary vector control intervention, and considerable effort has been made to achieve universal coverage. However, to date, LLINs have not had the desired impact on malaria burden in Uganda. High levels of pyrethroid resistance in malaria vectors may be contributing to the limited impact of LLINs.

All LLINs are currently treated with pyrethroid insecticides due to their favorable safety profile at low doses, repellent effects, and rapid killing. However, pyrethroid resistance has been reported across Africa and could threaten malaria control. Unpublished data suggests that pyrethroid resistance is widespread across Uganda.

The threat of pyrethroid resistance has generated interest in combining more than one insecticide mixture in LLINs. One approach is to combine a pyrethroid insecticide with a synergist, piperonyl butoxide (PBO), which is capable of inhibiting cytochrome P450s, to potentially overcome pyrethroid resistance in anopheline vectors.

LLINs that include PBO are anticipated to be more effective in areas where pyrethroid resistance is mediated by P450s. However, the impact of PBO LLINs is expected to vary according to the bioavailability and retention of PBO, and the level, intensity, and mechanisms of insecticide resistance for local vectors, as well as across different transmission settings.

Evidence of the impact of combination LLINs (with PBO) is urgently needed. The Uganda National Malaria Control Program and implementing partners carried out a universal LLIN campaign in 2016-17, supported by generous contributions from international donors, including The Against Malaria Foundation, The Global Fund to Fight AIDS, Tuberculosis and Malaria, the US President's Malaria Initiative, The AIDS Support Organisation, and the UK's Department for International Development. LLINs were distributed at no cost to all Ugandan households through a mass-distribution campaign. LLINs with, and without, PBO were distributed, presenting an opportunity to rigorously evaluate and compare the performance of combination LLINs (with PBO) and conventional LLINs (without PBO) on a wide-scale across a variety of malaria transmission intensities, vector ecologies, and insecticide resistance patterns. Following WHO guidance for robust evaluation of PBO nets, a cluster-randomized trial was carried out to compare the impact of LLINs with, and without, PBO in Uganda.

Objectives: The goal of the LLINEUP trial was to evaluate the impact of combination LLINs (with PBO), as compared to conventional LLINs (without PBO), on parasite prevalence, in Eastern and Western Uganda.

Primary scientific objective:

The trial tested the hypothesis that parasite prevalence will be lower in intervention clusters (health sub-districts randomized to receive PBO nets), than in control clusters (health sub-districts randomized to conventional nets) overall, and stratified by region (Eastern and Western regions).

Secondary scientific objectives:

To evaluate the impact of PermaNet 3.0 (with PBO), as compared to PermaNet 2.0 (without PBO), on parasite prevalence.
To evaluate the impact of Olyset Plus (with PBO), as compared to Olyset Net (without PBO), on parasite prevalence.
To determine factors associated with effectiveness of LLINs with PBO, as compared to LLINs without PBO, including the level of
insecticide resistance.
To assess net survivorship, durability, and bio-efficacy in Uganda.

Methodology:

Geographic Location/Study Sites: The LLINEUP study was conducted in 104 health sub-districts (clusters) in 48 districts in Eastern and Western Uganda.

Dates of Data Collection: March 2017 - September 2019

Baseline community (household and clinical/laboratory) and entomology surveys: March - June 2017
6-month follow-up surveys: September 2017, October - November 2017, January - February 2018, September 2018
12-month follow-up surveys: March 2018, May 2018, July - August 2018, March 2019
18-month follow-up surveys: September 2018, November 2018, January - February 2019, September 2019
25-month follow-up surveys: April - May 2019, June - July 2019, August - September 2019
Net durability assessment: March 2018, May 2018, July - August 2018, April - May 2019, June - July 2019, August - September 2019 (Data NOT available on ClinEpiDB)

Study Design: Cluster Randomized Controlled Trial

Data Collection and Eligibility Criteria:
At baseline (prior to LLIN distribution), and up to 4 times after nets were distributed (at 6, 12, 18 and 24-30 months after distribution), 50 households per cluster were randomly selected to take part in a cross-sectional household survey.

Inclusion criteria for cross-sectional household surveys:

At least one household resident between 2 - 10 years of age present (with an adult caregiver willing to provide informed consent for the
clinical survey)
At least one adult aged 18 years or older present
Adult is a usual resident who slept in the sampled household on the night before the survey
Agreement of the adult resident to provide informed consent for the household survey

Exclusion criteria for cross-sectional household surveys:

Dwelling destroyed or not found
Household vacant
No adult resident at home on more than 3 occasions

Clinical and laboratory evaluations were perfomed children aged 2 - 10 years, with the aim to recruit all eligible children from households enrolled at each study timepoint.

Inclusion criteria for cross-sectional clinical surveys:

Child aged 2-10 years
Usual resident who was present in the sampled household on the night before the survey
Agreement of parent/guardian to provide informed consent
Agreement of child aged 8 years or older to provide assent

Exclusion criteria for cross-sectional clinical surveys:

Child not home on day of survey

At each study timepoint, mosquitoes were collected from 10 randomly selected households in each cluster using prokopack aspirators. The aim was to collect 30-50 mosquitoes per cluster for genotypic monitoring. Entomology collections were carried out concurrently with the cross-sectional household surveys.

Inclusion criteria for cross-sectional entomology surveys:

At least one adult aged 18 years or older present
Adult is a usual resident who slept in the sampled household on the night before the survey
Agreement of the adult resident to provide informed consent for the entomology survey

Exclusion criteria for cross-sectional entomology surveys:

Dwelling destroyed or not found
Household vacant
No adult resident at home on more than 3 occasions

Durability and bio-efficacy of the LLINs were assessed one year after distribution of nets, concurrently with the 12-month and 24-30 month cross-sectional surveys.

The evaluation included cross-sectional community (household and clinical/laboratory) surveys (at baseline and at 6, 12, 18, and 25 months after LLIN distribution), entomological surveillance for insecticide resistance monitoring, assessment of net durability and bio-efficacy at 12 months, and assessment of net durability (only) at 25 months. The primary outcome of the trial was parasite prevalence, measured by microscopy in children aged 2 - 10 years in the follow-up cross-sectional surveys.

Study Arms: Clusters were randomly assigned to one of four study arms:

Conventional LLINs (without PBO): 52 clusters

PermaNet 2.0 (37 clusters)
Olyset Net (15 clusters)

Combination LLINs (with PBO): 52 clusters

PermaNet 3.0 (32 clusters)
Olyset Plus (20 clusters)

Study Documentation:

LLINEUP Protocol:

Study protocol
Study sensitization information sheet

LLINEUP Codebooks:

Household survey codebook
Clinical survey codebook
Entomology survey codebook

ClinEpiDB Data Integration: Data files were provided to ClinEpiDB as STATA .dta files. All identifying information was removed, including participant names and location data. These datasets were merged by unique ID and redundant or administrative columns were dropped from presentation on ClinEpiDB.org. All dates were obfuscated per participant through the application of a random number algorithm that shifted dates no more than seven days to comply with the ethical conduct of human subjects research.

Data Currently Available on ClinEpiDB: LLINEUP study data on net integrity and chemical composition are not included in the current release of ClinEpiDB.

Acknowledgements: We would like to thank the study team and study participants. Thanks to Susan Nayiga, Christine Nabirye, Lilian Taaka, Isiko Joseph, Erias Muyanda, Henry Opolot, Winnie Nuwagaba, Irene Bagala, Geoff Lavoy, Mugote Martin, Violet Tuhaise, Nicholas Wendo, Maxwell Kilama and the administration of the Infectious Diseases Research Collaboration for all of their contributions. We would also like to acknowledge and thank the members of the Uganda National Malaria Control Program and the Liverpool School of Tropical Medicine for logistical and other support rendered as we carried out these surveys. We are grateful to the district health, administrative, and political leadership teams for all their support and guidance during community entry in the 48 districts of the study area. Finally, we would like to extend our sincere thanks to Prof Immo Kleinschmidt, Prof Christian Lengeler, and Prof Feiko ter Kuile, who served as our advisory committee.

Financial Support: The LLINEUP trial was funded by grants through the Against Malaria Foundation (AMF), the Department for International Development / Innovative Vector Control Consortium, and the Bill & Melinda Gates Foundation (BMGF).

Ethics Statement: The study was approved by:

Ugandan National Council for Science and Technology (UNCST; ref. HS 2176)
Makerere University School of Medicine Research & Ethics Committee (SOMREC; 2016-133)
London School of Hygiene & Tropical Medicine Ethics Committee (LSHTM; ref. 12019)
Liverpool School of Tropical Medicine (ref. 16-072)

Written informed consent to participate in the study w be obtained by the head of household (or their designate) for all participating households.
This trial is registered with ISRCTN, ISRCTN17516395.

Last Updated: February 2, 2024The LLIN Evaluation in Uganda Project (LLINEUP), a pragmatic cluster-randomized trial embedded in the 2017-2018 long-lasting insecticidal net (LLIN) national distribution campaign, evaluated the effect of LLINs with and without piperonyl butoxide on malaria indicators in 104 health sub-districts (clusters) in Eastern and Western Uganda. Cross-sectional community surveys were conducted at baseline and at 6, 12, 18, and 25 months following LLIN distribution in ~50 randomly selected households per cluster; all children aged 2-10 years from enrolled households were assessed for malaria parasites, and a subset of 10 households per cluster were randomly selected for entomology surveys. To assess net integrity and chemical composition, 100 of each LLIN net type were withdrawn and replaced from selected households enrolled in the community surveys after 12 and 25 months.