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Environmental sanitary interventions for preventing active trachoma

  1. Mansur Rabiu1,*,
  2. Mahmoud B Alhassan2,
  3. Henry OD Ejere3,
  4. Jennifer R Evans4

Editorial Group: Cochrane Eyes and Vision Group

Published Online: 15 FEB 2012

Assessed as up-to-date: 23 SEP 2011

DOI: 10.1002/14651858.CD004003.pub4


How to Cite

Rabiu M, Alhassan MB, Ejere HOD, Evans JR. Environmental sanitary interventions for preventing active trachoma. Cochrane Database of Systematic Reviews 2012, Issue 2. Art. No.: CD004003. DOI: 10.1002/14651858.CD004003.pub4.

Author Information

  1. 1

    Prevention of Blindness Union, Riyadh, Saudi Arabia

  2. 2

    The National Eye Centre, Clinical Ophthalmology, Kaduna, Kaduna State, Nigeria

  3. 3

    Phoebe Putney Memorial Hospital, Phoebe Inpatient Medicine Specialists, Albany, Georgia, USA

  4. 4

    London School of Hygiene & Tropical Medicine, Cochrane Eyes and Vision Group, ICEH, London, UK

*Mansur Rabiu, Prevention of Blindness Union, Riyadh, Saudi Arabia. mrabiu@hotmail.com.

Publication History

  1. Publication Status: New search for studies and content updated (no change to conclusions)
  2. Published Online: 15 FEB 2012

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Characteristics of included studies [ordered by study ID]
Abdou 2010

MethodsRandomisation of 10 villages using simple random number table

Outcome assessors were partially masked

Losses to follow up was same for the both groups (11% versus 12%)

Some of the baseline variables were not equal for both groups for example the intervention villages had significantly higher prevalence of Chlamydia trachomatis  infection rates (26% versus 14%), higher proportion of 3 to 4 year olds and higher proportion of children living in compounds where garbage is observed within


Participants557 children: aged 1 to 5 years old in 10 villages in Niger republic


Interventions1.    The intervention villages had a health education programme which was implemented 3 months prior to the 2 year survey. A dedicated health educator used flip charts and interactive discussions in one or two village meetings to highlight the importance of personal hygiene

2.    Also all intervention villages had at least one hand pump well constructed (range of 1 to 3 wells) over the 2 year period


OutcomesPrevalence of active trachoma, prevalence of Chlamydia trachomatis from conjunctival swab


NotesBoth group of villages had access to an ongoing radio programme on trachoma, also it was reported both village groups were not far from the source of water


Risk of bias

BiasAuthors' judgementSupport for judgement

Recruitment biasLow riskWithin villages, we aimed to randomly select 60 children ages 1 to 5 years as sentinel markers of infection and trachoma. The census data from the house-to house survey that we collected was the basis for selection of children. Stratified random sampling was applied to select no more than one child per mother to minimize clustering of children within households. Of 591 children selected, 557 were examined (94%) at baseline. The same sample of children was surveyed for infection one year (January 2007) and two years (January 2008) later. ” Methods, page 2

"At one year, we re-surveyed 91% of the original sample (91% in intervention and 91% in the control villages). At two years, we re-surveyed 89% of the original sample (89% in the intervention and 88% in the control villages). The primary reason for loss to follow-up at both times was death of the child or child having left the village." Results, page 4

Baseline imbalanceHigh riskThe study populations in the two arms were mostly similar. The overall baseline prevalences of trachoma were similar in the intervention (43%) and control arms (40%, p=0.75). However, the prevalence of infection with C. trachomatis at baseline was 26% in the intervention villages and 14% in the control villages, significantly different (p=0.02) (Table 1). There was no difference by intervention arm in the proportion of female sentinel children, the number of children in the compound younger than 8 years, time to walk and wait to get water, or the size of the village (Table 1). However, there was imbalance in the ages of the sentinel children, with more 1–2 year-olds in the control villages, and more 3–4 year-olds in the intervention villages. The children in the intervention villages were also more likely to live in a compound with waste inside, 70%, compared to children in the control villages, 51% (Table 1).” Results, page 4

Blinding of participants and personnel (performance bias)
Active trachoma
High riskFor such community based interventions such as health education and provision of clean water supply it was not feasible to blind participants and personnel

Blinding of participants and personnel (performance bias)
Other outcomes
High riskFor community based interventions such as health education and provision of clean water supply it was not feasible to blind participants and personnel

Blinding of outcome assessment (detection bias)
Active trachoma
Unclear riskThe trachoma grader was masked to the intervention status of the village they were working in, although we cannot exclude their hearing from village residents.” Methods, page 3

Blinding of outcome assessment (detection bias)
Other outcomes
Low riskOcular C. trachomatis infection: "The laboratory personnel were masked to intervention and control status of the swabs received from the field." Methods, page 3

Incomplete outcome data (attrition bias)
All outcomes
Low risk"Two villages were extreme outliers: one had a small population and a low trachoma rate of 3% of children aged 5 years and younger; the other had a very high rate of 82%. These villages were removed from the trial, one from each arm, as they led to extreme imbalance at the outset (Figure 1)." Methods, page 2

"At one year, we re-surveyed 91% of the original sample (91% in intervention and 91% in the control villages). At two years, we re-surveyed 89% of the original sample (89% in the intervention and 88% in the control villages). The primary reason for loss to follow-up at both times was death of the child or child having left the village." Results, page 4

Selective reporting (reporting bias)Low riskThe pre-specified outcomes were infection with C. trachomatis and active trachoma and these were reported

Emerson 1999

MethodsQuasi-randomisation of 4 villages
Losses to follow up was 18%, but not similar in the study groups
Outcome assessor was masked


Participants1134 people of all ages in 4 villages in The Gambia


Interventions1. Insecticide spray (588 people in 2 villages) versus no intervention (546 people in 2 villages) for 3 months
Insecticide spray with 0.175% deltamethrin


OutcomesPrevalence of trachoma, fly-eye contact, fly population


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Recruitment biasLow risk"1124 people of all ages were screened for trachoma at baseline, of whom 924 (82%) were also screened at 3 months. Loss to follow-up, mainly owing to inclusion of temporary migrants in the baseline data, was similar for intervention and control groups (rate ratio for intervention v s control 1·13 [0·83–1·54])." Results, page 1402

Baseline imbalanceUnclear riskAlthough there was some evidence to suggest that the villages were similar (see quotes below) only 4 villages were randomised "arbitrarily" so other differences in other important confounders cannot be excluded

"Village communities were of similar size, age composition(table), and ethnicity (Wolof)". Results, page 1402

"Data on trachoma prevalence (figure) shows that there was no difference in the community prevalence of active trachoma at baseline in either village pair (wet season intervention 26/295 [8·8%] v s control 33/271 [12·2%]; dry season 34/189 [18·0] v s 27/169 [16·0])." Results, page 1402

Blinding of participants and personnel (performance bias)
Active trachoma
High riskCommunity based interventions like spray of insecticide in the villages cannot be masked from the villagers

Blinding of participants and personnel (performance bias)
Other outcomes
High riskCommunity based interventions like spray of insecticide in the villages cannot be masked from the villagers

Blinding of outcome assessment (detection bias)
Active trachoma
Unclear riskThe whole of each village community was screened for trachoma at baseline and at 3 months by the same community ophthalmic nurse, who was unaware of the treatment status of each village.” Methods, page 1401

Although the assessor did not know the status of the villages with respect to interventions,  the assessor may have heard the status of villages from the people  and may have noticed the fly traps set in the villages

Blinding of outcome assessment (detection bias)
Other outcomes
High riskFly related outcome measures: "Fly populations were monitored by four fish-baited traps placed in each village at an animal-tethering area, in a latrine, at the centre of a domestic compound, and at the main meeting point for 24 h every 2 weeks. To measure fly-eye contact in the dry season, hand-net collections of eye-seeking flies were made fortnightly from ten seated children for 15 min. Flies that touched the children’s eyes were collected and taken to the laboratory for identification". Methods, page 1401

No mention of blinding for this outcome

Incomplete outcome data (attrition bias)
All outcomes
Unclear risk% with ocular examination at follow-up varied in the different villages. Wet season control village 85%, wet season intervention village 77%; dry season control village 91%, dry season intervention village 74%. This was attributed to temporary migrants being examined at baseline

Selective reporting (reporting bias)Low riskThe study reported active trachoma but did not report ocular infection, however, the study report did not give any indication that data on ocular infection was recorded. The focus of the report was entomological

Emerson 2004

MethodsRandomisation by drawing pieces of folded paper from a hat
Outcome assessment was masked
Losses to follow up was not different between treatment groups and the control group


Participants7080 people 4 months and above of all sexes in 21 clusters of The Gambia


Interventions1. Insecticide spray (2244 people) versus no intervention (2606 people) for 6 months
Spray with water soluble permethrin
2. Latrine provision (2230 ) versus no intervention (2606) for 6 months

One latrine per household or 20 people whichever gave the most latrines


Outcomes1. Prevalence of active trachoma
2. Fly-eye contact (fly density)
3. Latrine utilisation


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Recruitment biasLow risk"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

Baseline imbalanceUnclear riskAnalysis 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

Blinding of participants and personnel (performance bias)
Active trachoma
High risk"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

Blinding of participants and personnel (performance bias)
Other outcomes
High risk"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

Blinding of outcome assessment (detection bias)
Active trachoma
Low risk"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 followup
survey, 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

Blinding of outcome assessment (detection bias)
Other outcomes
High risk"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

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll 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% CI
1·01–1·88) 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 between
the spray and control groups (p=0·71) or between the latrine and control groups (p=0·57).
Results, page 1095/1096

Selective reporting (reporting bias)Low risk"The primary outcome measures were fly-eye contact and prevalence of active trachoma." Methods, page 1094

These outcomes were reported.

Resnikoff 1995

MethodsPaper reports "Randomisation" (How randomisation was done could not be ascertained)
Assessor not masked


Participants1810 people of all ages in 4 villages of Mali


Interventions1) Health education (424) versus none (476) for 6 months
Health education was given by repeated information on personal, family hygiene and trachoma, at a frequency of one week per month


OutcomesIncidence of active trachoma
Incidence was determined by expressing the cumulative number of new cases of active trachoma over the follow up period of 6 months


NotesThe study had 4 arms, but we only used 2 arms
i.e. Health education versus no intervention
Age and sex distribution in the 2 villages were identical
The baseline prevalence of active trachoma in the 2 villages was not significantly different (21% versus 19% )
The follow up period in all the villages was identical - 6 months


Risk of bias

BiasAuthors' judgementSupport for judgement

Recruitment biasUnclear riskWith the permission of administrative and traditional authorities, all inhabitants of these four villages were surveyed”. Patients and methods, page 102

There was no discussion of recruitment bias in the paper and little information on response rates. It was unclear whether the community-level intervention here - provision of health education (based on community participation) and antibiotic distribution - would have affected recruitment to the study assessments

Baseline imbalanceUnclear riskAlthough there was some evidence to suggest that the villages were similar (see quotes and data below) only 4 villages were randomised so other differences in other important confounders cannot be excluded

Four villages, matched for size and epidemiological, economic and social conditions, were included in the study. All villages were situated the same distance from the health centre and each village possessed a school and was equipped with boreholes.” Patients and methods, page 102

The age and sex distribution was identical in all four villages” Results, page 103

Table 2 (page 109) shows the sex distribution (46% male in treatment community and 51% male in control community). No data on age distribution

Baseline prevalence of active trachoma (figure 1, page 109) just over 20% in treatment community and just under 20% in control community

Blinding of participants and personnel (performance bias)
Active trachoma
High riskFor community based interventions such as health education it was not feasible to mask participants and personnel

Blinding of participants and personnel (performance bias)
Other outcomes
High riskFor community based interventions such as health education it was not feasible to mask participants and personnel

Blinding of outcome assessment (detection bias)
Active trachoma
High riskFor community based interventions such as health education it would have been difficult to mask outcome assessors and this was not mentioned in the report

Blinding of outcome assessment (detection bias)
Other outcomes
High riskFor community based interventions such as health education it would have been difficult to mask outcome assessors and this was not mentioned in the report

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskAt the initial examination, 1810 subjects were enrolled and examined” Results, page 104.  Of these, 424 were from the community treated with topical antibiotics (village 2) and 476 were from the control community (village 4) (table 2 page 109)

A total of 347 subjects with active trachoma were included in the clinical trial. Two hundred and sixty five (76%) of these subjects were successfully followed for 6 months and were included in the analysis of the results.” Results, page 105)

However, the distribution of these cases by village is not reported. Using figure 1 (page 109) we can estimate that there were 89 cases of active trachoma in treatment community and 90 cases in control community. The “cure rate” in treatment village was 82% (estimated 73 people cured) and 36% in control community (estimated 33 people cured)

No information was given on possible reasons for loss to follow up

Selective reporting (reporting bias)Low riskOnly clinical outcomes reported but no indication that microbiological data collected

Stoller 2011

MethodsCluster-randomised trial of 24 communities in Ethiopia. A random selection of 60 children aged 0-9 years in each was monitored for clinical signs of trachoma and ocular chlamydial infection at baseline, 12 and 24 months


ParticipantsChildren resident in trachoma endemic communities


InterventionsMass treatment with azithromycin or topical tetracycline. 12 communities were randomised to intensive latrine promotion


OutcomesActive trachoma and ocular infection


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Recruitment biasLow riskThe subkebeles were randomly selected and the children to be examined in each sentinel team were randomly selected at all measurement intervals

Baseline imbalanceLow riskRandom selection of subkebeles and children to be examined

Baseline variables reported and were comparable  except for antibiotics coverage  which was higher in control arm

Table 1 page 79

Blinding of participants and personnel (performance bias)
Active trachoma
Unclear riskLatrine provision is difficult to mask but unclear the effect this would have had on the participants

Blinding of participants and personnel (performance bias)
Other outcomes
Unclear riskLatrine provision is difficult to mask but unclear the effect this would have had on the participants

Blinding of outcome assessment (detection bias)
Active trachoma
Unclear riskFor clinical trachoma grading assessors could not be effectively masked. Outcome assessors were from outside the area

Blinding of outcome assessment (detection bias)
Other outcomes
Low riskFor the primary outcome measure – ocular chlamydial infection using PCR, the assessors in the lab were masked

Incomplete outcome data (attrition bias)
All outcomes
Low riskA random sample of 60 participants sampled from each community at each time point

Selective reporting (reporting bias)Low riskRelevant outcomes reported. Authors have reported all outcomes measures they assessed

West 2006

MethodsCluster randomisation of 16 neighbourhoods (Balozi) by using a table of random number for allocation
Similar 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


Participants302 children 1 to 7 years in 16 Balozi in Kongwa, Tanzania


Interventions1. Insecticide spray (119 children in 8 Balozi) versus no intervention (183 children in 8 Balozi) for 1 year
Insecticide spray with 10% permethrin


OutcomesPrevalence of active trachoma, Chlamydia trachomatis infection rate (PCR), fly count


NotesNCT00347763


Risk of bias

BiasAuthors' judgementSupport for judgement

Recruitment biasLow risk"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

Baseline imbalanceUnclear riskAlthough 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

Blinding of participants and personnel (performance bias)
Active trachoma
High riskFor community based interventions such as fly control it was not feasible to mask participants and personnel and this was not described in the report

Blinding of participants and personnel (performance bias)
Other outcomes
High riskFor community based interventions such as fly control it was not feasible to mask participants and personnel and this was not described in the report

Blinding of outcome assessment (detection bias)
Active trachoma
Low riskTwo 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

Blinding of outcome assessment (detection bias)
Other outcomes
Unclear riskFor 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

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll 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

Selective reporting (reporting bias)Low riskActive trachoma and ocular infection were reported; no indication of any outcomes for which data collected and not reported

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Bailey 1991The study was an observational study (case-control), thus not a controlled clinical/community trial

Esrey 1991The paper was a 'traditional' review/overview of studies relating to improved water supply and sanitation

Potter 1993The article was an editorial of the BMJ, not a controlled trial

Pruss 2000The article was a review of studies relating to environmental sanitary interventions

Sutter 1983The allocation of intervention and control villages was decided long after intervention had started. Thus it was not a controlled trial

Taylor 2002The article was an editorial not a study/clinical trial

West 1988The article was a review/overview of community intervention programs for trachoma control; it was not a clinical/community trial

West 1989The study was an observational survey (cross-sectional study), not a controlled clinical trial

West 1996The intervention in this community based clinical trial was face washing, not environmental sanitary measures (as defined in the review)