Water, sanitation and hygiene: interventions and diarrhoea – a review Lorna Fewtrell & Jack Colford

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

Introduction (2) DIARRHOEA KILLS PEOPLE

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

Introduction (3)

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.

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

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

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

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)

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

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

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

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

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

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

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

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

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

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

Meta-analysis (3) Developing Countries Multiple (i.e. water, sanitation and hygiene [or health] education) SanitationHygiene HandwashingEducation SourcePt-of-use Water quality Community improvements Household connection Water supply

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

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

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 Meta-analysis(4)

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 a random effects model was used

Forest plot Effect Combined Ref 4 Ref 3 Ref 2 Ref 1 Random0.757 (0.425 – 1.349) Fixed (0.530 – 0.638) Heterogeneity p = 0.000

Results Key word searchInitial number of references Diarrhoea AND sanitation 636 Diarrhoea AND water quality 128 Diarrhoea AND water quantity 26 Diarrhoea AND hygiene 423 Drinking water AND intervention 111 Sanitation AND intervention 263 Hygiene AND intervention 459

Results

RefInterventionCountryLocationHealth outcome Age group Result95% CI Black et al., 1981 Handwashing with soap USASuburban (child care centres) Diarrhoea0 – 36 months Bartlett et al., 1988 Hygiene education USAUrban (child care centres) Diarrhoea0 – 35 months 1.09 Kotch et al., 1994 Handwashing + hygiene education USAUrban (child care centres) Diarrhoea0 – 36 months Carabin et al., 1999 Hygiene education CanadaUnstated (child care centres) Diarrhoea18 – 36 months Roberts et al., 2000 HandwashingAusUrban (child care centres) Diarrhoea0 – 36 months

Results RefAdeq. control Measure of confounders Random.Health indicator definition Health indicator recall Analysis by age Intervention /compliance assessed BlindingPlacebo 1Yes Non standard DailyYes No 2YesNot clearYesNon standard Daily or twice weekly NANoSome 3NoYesNoNon standard 2 weeksYes No 4Yes NoneDailyNAYesNot clear No 5Yes Standard3 weeksYes SomeNo Hypothetical example

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

Hygiene

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

Hygiene (2) Random (0.52 – 0.76) Fixed (0.72 – 0.78) Heterogeneity - p = 0.000

Hygiene (3) Overall summary measure (0.524 – 0.765) Removing poor quality studies (0.400 – 0.749)

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

Hygiene (summary)

Sanitation

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

Water supply

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

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

Water supply (3) Effect Combined Tonglet et al., 1992 Wang et al., 1989 Esrey et al., 1988 Ryder et al., 1985 Bahl, 1976 Azurin and Alvero, 1974 Random – 0.75 (0.62 – 0.91) Fixed – 0.63 (0.63 – 0.64) Heterogeneity - p < 0.2

Water supply (4) Excluding the ecological study: Pooled RR (0.632 – 1.195) Excluding the ecological study and restricting analysis to ‘standard’ diarrhoea Pooled RR ( )

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)

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 (0.464 – 0.669)

Water supply (summary)

Water quality

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

Water quality (2) Overall intervention effective – pooled estimate (0.534 – 0.885): 31% reduction This included both source and household treatment

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

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

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

Water quality (summary)

Multiple

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

Multiple interventions (2) Effect Combined Nanan et al., 2003 Messou et al., 1997 Hoque et al., 1996 Mertens et al., 1990a,b Aziz et al., 1990 Random (0.64 – 0.77) Fixed (0.68 – 0.76) Heterogeneity - p < 0.2

Overall summary pooled effect 1 HH treatment - rural settings HH treatment only Source treatment only Water quality Standpipe and diarrhoea HH connection and diarrhoea Diarrhoea only Water supply Sanitation Education Handwashing Excluding poor quality studies Hygiene Multiple HH treatment - excl poor quality studies HH treatment - urban + periurban settings

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

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?

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

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

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

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 >2 weeks 32% of studies (19 from 60) classed as poor! Results generally improved if these were removed

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

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

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

Comparison with Esrey

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

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

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

If we do it right we can save lives – we can make a difference BUT……….

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