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Study Title and Description

Role of flies and provision of latrines in trachoma control: cluster-randomised controlled trial



Key Questions Addressed
1 What is the effect of environmental sanitary interventions for preventing active trachoma?
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Primary Publication Information
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TitleData
Title Role of flies and provision of latrines in trachoma control: cluster-randomised controlled trial
Author Emerson PM, Lindsay SW, Alexander N, Bah M, Dibba SM, Faal HB
Country
Year 2004
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Environmental sanitary interventions for preventing active trachoma 2012
Arms
Number Title Description Comments
1 Insecticide spray Spray with water soluble permethrin
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2 Latrine provision One latrine per household or 20 people whichever gave the most latrines.
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3 No intervention
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Design Details
Question... Follow Up Answer Follow-up Answer
Page 1093-8
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Methods Randomisation by drawing pieces of folded paper from a hatOutcome assessment was maskedLosses to follow up was not different between treatment groups and the control group
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Interventions 1. Insecticide spray (2244 people) versus no intervention (2606 people) for 6 monthsSpray with water soluble permethrin2. Latrine provision (2230 ) versus no intervention (2606) for 6 monthsOne latrine per household or 20 people whichever gave the most latrines
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Outcomes 1. Prevalence of active trachoma2. Fly-eye contact (fly density)3. Latrine utilisation
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Notes
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Participants 7080 people 4 months and above of all sexes in 21 clusters of The Gambia
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Recruitment bias:Authors' judgement Low risk
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Recruitment bias:Support for judgement "Everybody over 4 months of age was recruited to the study provided that informed consent was obtained and they intended to stay in the village for 6 months." Methods, page 1094 There was no discussion of recruitment bias in the paper but the review authors made the judgement that the provision of community-level interventions in this study (fly control/latrines) was unlikely to influence the recruitment of participants to the survey of active trachoma and fly-eye contact
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Baseline imbalance:Authors' judgement Unclear risk
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Baseline imbalance:Support for judgement Analysis done on pairs based on recruitment to the study but "Clusters were at least 1·5 km apart but were not matched since this would have reduced the interpretability and statistical power of the study". Methods, page 1093 Clusters and study populations appeared similar with respect to sanitation, access to water, housing quality, age, sex and ethnicity. There were some differences in trachoma status and fly numbers but unclear as to how important these would be. As only 21 clusters randomised baseline differences in other important confounders cannot be excluded
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Blinding of participants and personnel (performance bias)Active trachoma:Authors' judgement High risk
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Blinding of participants and personnel (performance bias)Active trachoma:Support for judgement "They [the clusters] were recruited in sets of three and randomly assigned to insecticide spray, latrines, or control by drawing from a hat at a meeting of village heads held at the district chief's office." Methods, page 1094
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Blinding of participants and personnel (performance bias)Other outcomes:Authors' judgement High risk
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Blinding of participants and personnel (performance bias)Other outcomes:Support for judgement "They [the clusters] were recruited in sets of three and randomly assigned to insecticide spray, latrines, or control by drawing from a hat at a meeting of village heads held at the district chief's office." Methods, page 1094
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Blinding of outcome assessment (detection bias)Active trachoma:Authors' judgement Low risk
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Blinding of outcome assessment (detection bias)Active trachoma:Support for judgement "Both eyes were inspected for trichiasis and the right eyelid everted and examined with 2·5 magnification. If trachomatous follicles were present that did not qualify as grade TF (fewer than five, or <0·5 mm in diameter) then the left eyelid was also examined. A single photograph using either slide film (Fujichrome 100ASA) or a digital image(696405 pixels) of the everted eyelid was taken to verify field grades." Methods, page 1095 "Photographs of eyes from study participants were graded by clinicians who were unaware of the field diagnosis, whether the photograph was from the baseline or followupsurvey, or if the participant was from an intervention or control cluster". Methods, page 1095 "The kappa values were also similar for each of the treatment groups in both baseline and follow-up surveys: control group at baseline 0·76, follow-up 0·63; spray group, 0·60 and 0·84; latrine group, 0·63 and 0·95, suggesting that there was no systematic bias in the field diagnoses." Results, page 1097
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Blinding of outcome assessment (detection bias)Other outcomes:Authors' judgement High risk
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Blinding of outcome assessment (detection bias)Other outcomes:Support for judgement "We monitored fly-eye contact once every 2 weeks in each cluster by use of eight 15 min hand-net catches of eyeseeking flies from the faces of volunteer children younger than 5 years of age. A contact was defined by the feet or proboscis of a fly touching the eye, lid margin, or lashes. The fly making the contact was caught in a hand-net; which was passed to an assistant who transferred the fly to a tube. Flies were identified by magnification." Methods, page 1094 No mention of masking for this outcome
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Incomplete outcome data (attrition bias):Authors' judgement Low risk
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Incomplete outcome data (attrition bias):Support for judgement All clusters completed trial and loss to follow-up similar in the clusters "All 21 clusters were recruited and visited at follow-up; 7080 people were recruited from these clusters, and 6087 (86%) were seen at follow-up (figure 1). The number of participants lost to follow-up did not differ between either the spray and control groups (p=0·08) or between the latrine and control groups (p=0·55). The proportion lost because of travelling also did not differ between these groups (p=0·84 and p=0·57, respectively). Participants with active trachoma at baseline were 1·38 (95% CI1·01–1·88) more likely to be lost to follow-up than were those without active trachoma, but the proportions with active trachoma lost to follow-up did not differ betweenthe spray and control groups (p=0·71) or between the latrine and control groups (p=0·57). Results, page 1095/1096
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Selective reporting (reporting bias):Authors' judgement Low risk
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Selective reporting (reporting bias):Support for judgement "The primary outcome measures were fly-eye contact and prevalence of active trachoma." Methods, page 1094 These outcomes were reported.
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Study design Cluster randomized trial (drawing pieces of folded paper from a hat)
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Unit of analysis Individual
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Number randomly assigned Clusters: 21; Individuals: 7080; Insecticide spray: 2244 people; Latrine provision: 2230 people; No intervention: 2606 people
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Losses to follow-up 14%: The number of participants lost to follow-up did not differ between either intervention group and the control
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Number analyzed 6087
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Country Gambia
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Age of participants All ages
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Equivalence of baseline characteristics Clusters and study populations appeared to be similar with respect to sanitation, access to water, housing quality, age, sex, and ethnicity
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Intervention 1 Insecticide spray (spray with water soluble permethrin)
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Intervention 2 Latrine provision (one latrine per household or 20 people; whichever gave the most)
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Length of follow up 6 months
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Primary outcome, as defined in study report Fly-eye contact and prevalence of active trachoma
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Secondary outcome(s), as defined in study report
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Times at which outcome(s) are assessed Fly-eye contact every 2 weeks
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Intervention 3 No intervention
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Results & Comparisons


Results Data
Outcome: Number of participants with TF or TI      Population: All Participants Between-Arm Comparisons
Time Point Measure Insecticide spray Latrine provision No intervention Comparison Measure Insecticide spray vs. No intervention Latrine provision vs. No intervention


6 months

N Analyzed 2244 2230 2606 Mean Difference 3.47% 1.26%
Counts Percent reduction in active trachoma 55.8% 29.5%
Outcome: Latrine utilisation      Population: All Participants
Time Point Measure Insecticide spray Latrine provision No intervention


6 months

N Analyzed 2244 2230 2606
Counts 98%
Outcome: Fly density      Population: All Participants Between-Arm Comparisons
Time Point Measure Insecticide spray Latrine provision No intervention Comparison Measure Insecticide spray vs. No intervention


6 months

N Analyzed 2244 2230 2606 Percent fewer Musca sorbens flies 88%
Counts Percent fewer Musca dormestica flies 92%

Adverse Events
Arm or Total Title Description Comments