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Water, sanitation and hygiene: interventions and diarrhoea a review

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Lorna Fewtrell & Jack Colford. Introduction (1) ... Black et al., 1981. 95% CI. Result. Age group. Health outcome. Location. Country. Intervention ... – PowerPoint PPT presentation

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Title: Water, sanitation and hygiene: interventions and diarrhoea a review


1
Water, sanitation and hygiene interventions and
diarrhoea a review
  • Lorna Fewtrell Jack Colford

2
Introduction (1)
  • Diarrhoeal disease continues to be one of the
    leading causes of morbidity and mortality in
    developing countries

3
Introduction (2)
  • DIARRHOEA KILLS PEOPLE

4
Introduction (3)
  • The important role of sanitation and safe water
    in maintaining health has been recognised for
    centuries
  • 1980s International Drinking Water Supply and
    Sanitation Decade
  • Reviews of the effectiveness of various levels of
    water supply and sanitation published

5
Introduction (3)
6
Objectives
  • These are now quite dated so the objective of
    this review was to update the previous work in
    the area with a view to informing interested
    parties on the relative effectiveness of possible
    interventions addressing water, sanitation and
    hygiene.

7
Search strategy (1)
  • Medline and Embase databases searched using key
    words pairing, diarrhoea or intervention against
  • Sanitation
  • Water quality
  • Water quantity
  • Hygiene
  • Drinking water

8
Search strategy (2)
  • Database searches were restricted to papers
    relating to humans dated prior June 26, 2003
  • The Esrey reviews were used to identify studies
    published prior to 1985
  • Abstracts, where available, were examined and
    papers which appeared to be relevant were
    obtained for further review

9
Initial selection criteria
  • The article reported diarrhoea morbidity as a
    health outcome under endemic (or non-outbreak)
    conditions and
  • The article reported specific water, sanitation
    and/or hygiene intervention(s), or some
    combination thereof

10
Intervention classification (1)
  • Hygiene includes hygiene and health education
    and the encouragement of specific behaviours
    (such as handwashing)
  • Sanitation those interventions that provided
    some means of excreta disposal, usually the
    provision of latrines (at public or private
    level)

11
Intervention classification (2)
  • Water supply included the provision of a new
    water source and/or improved distribution (such
    as installation of a handpump or a household
    connection)
  • Water quality these were related to the
    provision of water treatment, either at source or
    household level

12
Intervention classification (3)
  • Multiple those which introduced water,
    sanitation and hygiene (or health education)
    elements to the study population

13
Data extraction (1)
  • Study location
  • Study design
  • Study length
  • Study period
  • Sample size
  • Data collection method
  • Participant age band
  • Confounders examined

14
Study design
  • Range of epidemiological study designs that can
    be (and in many cases, have been) applied to
    study the impact of improvements to water,
    sanitation and health
  • Intervention
  • Case-control
  • Ecological

15
Data extraction (2)
  • Illness definition
  • Recall period
  • Type level of water supply and sanitation
    (pre-intervention)
  • Water source
  • Intervention
  • Relative risk and 95 CI

16
Data extraction (3)
  • Relative risk included
  • odds ratios, incidence density ratios, cumulative
    incidence ratios
  • When both adjusted and unadjusted (for other
    covariates) measures were reported the most
    adjusted estimate was used

17
Data extraction (4)
  • RR and 95 CI expressed such that a RR of less
    than unity means that the intervention group has
    a reduced frequency of diarrhoea in comparison to
    the control group

18
Meta-analysis (intro)
  • Meta-analysis is a tool that allows the
    statistical pooling of data across studies to
    generate a summary estimate of effects
  • Where effect is any measure of association
    between exposure and outcome (e.g. odds ratio)
  • It is not always appropriate to conduct a
    meta-analysis

19
Meta-analysis(1)
  • Risk estimates from the selected studies were
    pooled in meta-analysis using STATA software
    (STATA Corporation, College Station, TX, USA,
    version 8)
  • STATA commands for meta-analysis are not an
    integral part of the original software but are
    additional, user-written, add-on programs that
    can be freely downloaded

20
(No Transcript)
21
Meta-analysis(2)
  • Studies were stratified, prior to data analysis,
    into groups of related interventions
  • Studies were divided according to the level of
    country development and then analysed by
    intervention type

22
Meta-analysis (3)
23
Meta-analysis(4)
  • Where sufficient studies were available within
    each intervention they were further examined in
    sub-group analysis defined by
  • Health outcome
  • Age groups
  • Pre-intervention water and sanitation situation

24
Pre-intervention scenarios
  • F basic water and basic sanitation
  • Eb improved water and basic sanitation
  • Ea basic water and improved sanitation
  • D improved water and improved san

25
Meta-analysis(4)
  • Where sufficient studies were available within
    each intervention they were further examined in
    sub-group analysis defined by
  • Health outcome
  • Age groups
  • Pre-intervention water and sanitation situation
  • Design
  • Location
  • Study quality

26
Meta-analysis(5)
  • Forest plots and pooled estimates of risk were
    generated
  • Both fixed and random effects estimates were
    prepared for all analyses
  • If the heterogeneity is less than 0.2 - a random
    effects model was used

27
Forest plot
Random 0.757 (0.425 1.349) Fixed 0.582 (0.530
0.638) Heterogeneity p 0.000
28
Results
29
Results
30
Results
31
Results
32
Results
Hypothetical example
33
Results
  • All the data are outlined in the report
  • Following is a summary of the intervention
    studies reported from developing countries on an
    intervention-by intervention basis

34
Hygiene
35
Hygiene (1)
  • 15 papers
  • 13 studies
  • 11 included in the meta-analysis

36
Hygiene (2)
Random - 0.63 (0.52 0.76) Fixed - 0.75 (0.72
0.78) Heterogeneity - p 0.000
37
Hygiene (3)
  • Overall summary measure
  • 0.633 (0.524 0.765)
  • Removing poor quality studies
  • 0.547 (0.400 0.749)

38
Hygiene (4)
  • Handwashing seemed to be more effective than
    hygiene education
  • There seemed to be a greater impact on diarrhoea
    than dysentery (but only 2 dysentery data points)
  • Intervention was effective whatever the baseline
    scenario, but more so where there was poorer
    water and/or sanitation facilities

39
Hygiene (summary)
40
Sanitation
41
Sanitation (1)
  • 4 studies
  • 2 included in the meta-analysis (1 of which
    examined cholera)
  • Pooled estimate 0.678 (0.529 0.868)
  • Adding an additional study (1957 USA) pooled
    estimate 0.642 (0.514 0.802)
  • 1/5 not considered to be poor quality

42
Water supply
43
Water supply (1)
  • These included the provision of new or improved
    water supply and/or improved distribution
  • Complex could include public OR private water
    supply

44
Water supply (2)
  • 9 studies, 6 could be included in meta-analysis
  • Initial results suggested a significant impact
    0.749 (0.618 0.907) BUT that included an
    ecological study and one examining cholera

45
Water supply (3)
Random 0.75 (0.62 0.91) Fixed 0.63 (0.63
0.64) Heterogeneity - p lt 0.2
46
Water supply (4)
  • Excluding the ecological study
  • Pooled RR 0.869 (0.632 1.195)
  • Excluding the ecological study and restricting
    analysis to standard diarrhoea
  • Pooled RR 1.031 (0.730 -1.457)

47
Water supply (5)
  • Standpipe versus household on diarrhoea -
    suggests a small but not stat significant effect
    BUT.
  • Only two studies considered to be of good quality
    one of each
  • HH 0.62 (0.59 0.65)
  • Standpipe 0.95 (0.88 1.00)

48
Water supply (6)
  • In one of the hh connection studies, household
    storage was still practiced omitting this study
    and adding two from developed countries (1976 UK
    1969 USA) suggests that a household supply can
    be an effective intervention for reducing
    diarrhoea 0.557 (0.464 0.669)

49
Water supply (summary)
50
Water quality
51
Water quality (1)
  • 15 studies
  • All had data suitable for inclusion in the
    meta-analyses
  • 5 papers judged to be poor quality

52
Water quality (2)
  • Overall intervention effective pooled estimate
    0.687 (0.534 0.885)
  • 31 reduction
  • This included both source and household treatment

53
Water quality (3)
  • Source treatment (3)
  • Source only a reduction in diarrhoea seen but
    not stat significant. Some problems with the
    studies.

54
Water quality (4)
  • Household treatment/safe storage (12)
  • Household treatment effective 0.645 (0.475
    0.875)
  • 35 reduction
  • Impact increased if poor quality studies are
    removed from the analysis
  • 39 reduction

55
Water quality (5)
  • Examining the effect of study location on the
    intervention, showed that there seemed to be a
    greater impact seen on diarrhoea in people from
    rural communities
  • 47 reduction
  • compared to urban/periurban settings
  • 23 reduction

56
Water quality (summary)
57
Multiple
58
Multiple interventions (1)
  • Nine papers
  • 7 studies, 6 of which had risk estimates and 5 of
    which were used in the meta-analysis
  • 5/6 risk measures less than 1

59
Multiple interventions (2)
Random - 0.69 (0.64 0.77) Fixed - 0.72 (0.68
0.76) Heterogeneity - p lt 0.2
60
Overall summary
61
Discussion (hygiene)
  • Most conducted where water and sanitation already
    improved
  • Seem to be effective whatever the starting
    conditions
  • Actual interventions vary widely
  • Diarrhoeal reductions improved when poor papers
    excluded

62
Discussion (sanitation)
  • Few studies looked at actual sanitation
    interventions
  • Most (75) were classified as poor quality
  • Meta-analysis does suggest that the intervention
    is effective
  • Scope for much more work here dry sanitation
    study?

63
Discussion (water supply)
  • Public and private supplies
  • Compliance generally poorly assessed, with few
    data on water usage
  • Suggestion that household connection is effective
    in reducing diarrhoea levels, especially bringing
    in 2 studies conducted in developed countries

64
Discussion (water quality)
  • Source treatment and household treatment
  • Household treatment particularly effective
    (especially when poor quality papers removed from
    analysis)
  • Range of household treatment types
  • Source treatment studies hampered by
    methodological problems

65
Discussion (multiple)
  • Complex! All provided water supply, sanitation
    and hygiene measures but final provision varied
  • None reported final water quality (after storage)
    and none employed household treatment
  • Lack of additive effect, when compared to single
    interventions disappointing

66
Discussion (study quality)
  • Studies classified as poor quality if
  • Lack of adequate control group
  • No measurement of confounding factors
  • Undefined health indicator and/or
  • Health indicator recall of gt2 weeks
  • 32 of studies (19 from 60) classed as poor!
    Results generally improved if these were removed

67
Discussion (baseline scenario)
  • Reasonable to expect diarrhoea reduction to be
    dependent upon starting conditions
  • F basic water, basic sanitation
  • Eb improved water, basic sanitation
  • Ea basic water, improved sanitation
  • D improved water, improved sanitation
  • Not surprisingly, most studies were conducted in
    areas classified as F so not possible to
    examine except for hygiene

68
Discussion (pre-intervention)
  • Most studies do not ascertain (or report)
    pre-intervention diarrhoea level or water,
    sanitation and hygiene behaviour

69
Discussion (hh storage)
  • Household storage of water prior to consumption
    is common
  • In many intervention studies (except hh treatment
    ones), this is often not considered
  • Contamination of stored water is extremely common

70
Comparison with Esrey
71
Conclusions
  • Some 15 years on from Esrey et al. and over 20
    years from Blum and Feachem diarrhoea is still
    killing people in developing countries
  • Loosing data
  • Poor community involvement

72
Conclusions
  • There is a lot more that we could look at
  • Water usage
  • Sustainability of the interventions
  • Sustainability of the health effects
  • Different ways of encouraging intervention uptake
  • Other health outcomes

73
Conclusions
  • In study terms in has to be said that often
  • WE COULD DO BETTER!

74
Conclusions
  • If we do it right we can save lives we can make
    a difference
  • BUT.

75
Thanks to
  • Wayne Enanoria and Jack Colford
  • Rachel Kaufmann
  • Jamie Bartram and Dave Kay
  • NAS, CDC, WELL, WASH, World Bank, Water Aid, WHO,
    UNICEF
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