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Study Title and Description

Intensive insecticide spraying for fly control after mass antibiotic treatment for trachoma in a hyperendemic setting: a randomised 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 Intensive insecticide spraying for fly control after mass antibiotic treatment for trachoma in a hyperendemic setting: a randomised trial
Author West SK, Emerson PM, Mkocha H, McHiwa W, Munoz B, Bailey R, et al
Country
Year 2006
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 Fly control interventions Insecticide spray with 10% permethrin
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2 No intervention
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Design Details
Question... Follow Up Answer Follow-up Answer
Page 596-600
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Methods Cluster randomisation of 16 neighbourhoods (Balozi) by using a table of random number for allocationSimilar follow up periods and similar lost to follow up in the study groups, but lost to follow up 25 to 30%Outcome assessors were masked
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Interventions 1. Insecticide spray (119 children in 8 Balozi) versus no intervention (183 children in 8 Balozi) for 1 yearInsecticide spray with 10% permethrin
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Outcomes Prevalence of active trachoma, Chlamydia trachomatis infection rate (PCR), fly count
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Notes NCT00347763
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Participants 302 children 1 to 7 years in 16 Balozi in Kongwa, Tanzania
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Recruitment bias:Authors' judgement Low risk
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Recruitment bias:Support for judgement "Follow-up rates of children in the intervention balozi were 77% at 6 months and 67% at 1 year, and 75% and 69% in controls, respectively. Children lost to follow-up were either temporarily out of their balozi, had died, or had moved away." Results, page 598 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) was unlikely to influence the recruitment of participants to the study
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Baseline imbalance:Authors' judgement Unclear risk
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Baseline imbalance:Support for judgement Although there was some evidence to suggest that the clusters (balozi) were similar (see quotes and data below) only 16 balozi were randomised so differences in other important confounders cannot be excluded "The mean household size did not differ between the balozi randomised to intervention and the control neighbourhoods." Results, page 598 "The mean number of flies in the balozi per day at baseline (measured 5 weeks before the start of spraying) did not differ between the intervention and control groups." Results, page 598 Mean prevalence of trachoma: - 63% intervention; 68% control active trachoma - 29% intervention; 35% control ocular infection "Trachoma and infection prevalence rates adjusted for clustering at the balozi level, period of enrolment, and potentially confounding factors of age, sex, baseline trachoma status, and antibiotic treatment." Statistical analysis, page 598
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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 For community based interventions such as fly control it was not feasible to mask participants and personnel and this was not described in the report
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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 For community based interventions such as fly control it was not feasible to mask participants and personnel and this was not described in the report
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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 "Two graders assessed the photographs independently, masked to the intervention status and time of the examination. [...] Outcomes are reported on the basis of masked photographic gradings" Procedures, page 597
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Blinding of outcome assessment (detection bias)Other outcomes:Authors' judgement Unclear risk
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Blinding of outcome assessment (detection bias)Other outcomes:Support for judgement For community based interventions such as fly control it was not feasible to mask the entomological outcome assessors and this was not described in the report However, for laboratory assessment of ocular C. trachomatis infection masking should be relative straightforward however this was not described in the report
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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 16 balozi initially selected were included in the trial. [...] Follow-up rates of children in the intervention balozi were 77% at 6 months and 67% at 1 year, and 75% and 69% in controls, respectively. Children lost to follow-up were either temporarily out of their balozi, had died, or had moved away." Results, page 598
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Selective reporting (reporting bias):Authors' judgement Low risk
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Selective reporting (reporting bias):Support for judgement Active trachoma and ocular infection were reported; no indication of any outcomes for which data collected and not reported
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Study design Cluster randomized trial (table of random numbers)
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Unit of analysis Individual
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Number randomly assigned Neighborhoods: 16; Children: 302; Intervention: 8 clusters with 119 children; Control: 8 clusters with 183 children
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Losses to follow-up Intervention loss to follow up: 23% at 6 months, and 33% at 1 year; Control loss to follow up: 25% at 6 months, and 31% at 1 year
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Number analyzed 6 months intervention: 92; 6 months control: 137; 1 year intervention: 80; 1 year control: 126
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Country Tanzania
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Age of participants 1 - 7 years
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Equivalence of baseline characteristics Some evidence suggests clusters were similar, but differences in other important confounders cannot be exlcluded
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Intervention 1 Insecticide spray (10% permethrin)
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Intervention 2 No intervention
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Length of follow up 1 year
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Primary outcome, as defined in study report Prevalence of active trachoma
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Secondary outcome(s), as defined in study report Chlamydia trachomatis infection rate, fly count
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Times at which outcome(s) are assessed 6 months and 1 year
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Intervention 3
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Results & Comparisons


Results Data
Risk Difference (RD) P-Value Risk Difference (RD) P-Value
Outcome: Number of participants with TF or TI      Population: All Participants Between-Arm Comparisons
Time Point Measure Fly control interventions No intervention Comparison Measure Fly control interventions vs. No intervention


6 months

N Analyzed 119 183 -10%
Counts 20% 30% 0.07


12 months

N Analyzed 119 183 -1%
Counts 43% 44% 0.09
Risk Difference (RD) P-Value
Outcome: Chlamydia trachomatis      Population: All Participants Between-Arm Comparisons
Time Point Measure Fly control interventions No intervention Comparison Measure Fly control interventions vs. No intervention


6 months

N Analyzed 119 183 2.7%
Counts 9.4% 6.7% 0.45
Risk Difference (RD) P-Value Risk Difference (RD) P-Value
Outcome: Fly density      Population: All Participants Between-Arm Comparisons
Time Point Measure Fly control interventions No intervention Comparison Measure Fly control interventions vs. No intervention


6 months

N Analyzed 119 183
Counts < 0.05


12 months

N Analyzed 119 183
Counts < 0.05

Adverse Events
Arm or Total Title Description Comments