Institute of Applied Health Research, University of Birmingham, Birmingham, UK
Center for Global Health Equity, University of Michigan, Ann Arbor, Michigan, USA.
BMJ Glob Health. 2022 May;7(5). doi: 10.1136/bmjgh-2022-008521.
Water, sanitation and hygiene interventions have been the subject of cluster trials of unprecedented size, scale and cost in recent years. However, the question 'what works in water, sanitation, hygiene (WASH)?' remains poorly understood. Evaluations of community interventions to prevent infectious disease typically use lab-confirmed infection as a primary outcome; however, WASH trials mostly use reported diarrhoea. While diarrhoea is a significant source of morbidity, it is subjected to significant misclassification error with respect to enteric infection due to the existence of non-infectious diarrhoea and asymptomatic infection. We show how this may lead to bias of estimated effects of interventions from WASH trials towards no effect. The problem is further compounded by other biases in the measurement process. Alongside testing for infection of the gut, an examination of the causal assumptions underlying WASH interventions present several other reliable alternative and complementary measurements and outcomes. Contemporary guidance on the evaluation of complex interventions requires researchers to take a broad view of the causal effects of an intervention across a system. Reported diarrhoea can fail to even be a reliable measure of changes to gastrointestinal health and so should not be used as a primary outcome if we are to progress our knowledge of what works in WASH.
近年来，水、环境卫生和个人卫生干预措施已经成为规模空前、范围广泛和成本高昂的群组试验的主题。然而，“水、环境卫生和个人卫生（WASH）方面什么有效？”这个问题仍未得到很好的理解。评估社区干预措施以预防传染病的研究通常将实验室确认的感染作为主要结果；然而，WASH 试验大多使用报告的腹泻。虽然腹泻是发病率的一个重要来源，但由于非感染性腹泻和无症状感染的存在，它在肠道感染方面存在显著的分类错误。我们展示了这可能如何导致 WASH 试验中干预效果的估计值偏向于无效果。这个问题因测量过程中的其他偏差而进一步加剧。除了检测肠道感染外，对 WASH 干预措施背后的因果假设进行检验，还需要对其他可靠的替代和补充测量和结果进行检查。复杂干预措施评估的当代指南要求研究人员从系统的角度广泛考虑干预措施的因果效应。如果我们要提高对 WASH 有效性的认识，那么报告的腹泻甚至不能可靠地衡量胃肠道健康的变化，因此不应作为主要结果。
