Evaluation of a water, sanitation, and hygiene education intervention on diarrhoea in northern Pakistan

In 2001, the Department of Community Health Sciences, Aga Khan University (AKU-CHS) developed a planning and monitoring strategy to evaluate Pakistan's Water and Sanitation Extension Programme (WASEP). Researchers conducted a case-control study to evaluate whether, after selected confounders were controlled for, children aged less than 6 years with diarrhoea were more or less likely to reside in villages that participated in WASEP than in villages that did not participate. Researchers specifically selected an evaluation period of July-September to maximise the number of diarrhoea cases seen at the health centres and thereby to achieve the calculated sample size. In addition, evaluation would have been more difficult during the winter months, when communication and transportation can be challenging in some parts of the region.

Overall, findings indicate that children not living in WASEP villages had a 33% higher adjusted odds ratio for having diarrhoea than children living in WASEP villages. Boys had 25% lower odds of having diarrhoea than girls. A 2.6% decrease was found in the odds of diarrhoea for every yearly increase in the mother's age and a 1.4% decrease for every monthly increase in the child's age.

In the Discussion section of the evaluation, AKU-CHS evaluators reflect on the fact that these findings conflict with some of WASEP's own. Namely, WASEP reported a 50% reduction in the incidence of diarrhoea in project villages on the basis of a preliminary pre- and post-intervention comparison that used data from their monitoring programme. AKU-CHS researchers speculate that WASEP's findings "may be due in part to an ecological effect caused by a decreasing background level of diarrhoea during the project. Such an ecological effect would not be accounted for in a pre-post analysis, in which only internal comparisons are made over time: a case-control design would more easily account for such trends."

Data collected on knowledge, attitude, and practices about health and hygiene showed virtually no differences between cases and controls. Evaluators speculate that response bias from participants giving socially acceptable answers to questions may have accounted for the small differences observed. They hypothesise that this lack of demonstrated impact may also reflect the presence of organisations other than WASEP that delivered similar health-related interventions in the project area. Approximately one-third of cases and controls resided in villages where other groups were working on water, sanitation, and hygiene-related issues.

Evaluators conclude that "The health impact and outcome indicators of a water and sanitation programme are not easy to define and are difficult to measure, especially if the effect of each component is to be determined separately. It is more feasible to regard such programmes as a "package" of services and actions that, taken together, can influence the health of a person and the health status of a community" (footnote numbers omitted).

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