University of Surrey, UK.
Lancet Infect Dis. 2010 Aug;10(8):536-44. doi: 10.1016/S1473-3099(10)70123-7. Epub 2010 Jul 9.
Sanitation is inadequate in most cities in developing countries, with major effects on infectious disease burden: in this situation, is piped sewerage an appropriate solution, or should efforts focus on systems based on onsite solutions, such as latrines? We reviewed the effects of the presence of sewerage systems on diarrhoeal disease and related outcomes. We included only observational studies because so far there have been no randomised controlled trials.
We identified relevant studies by use of a comprehensive strategy including searches of Medline and other databases from 1966 to February, 2010. In studies that compared sewerage with one other sanitation category, we used relative risk (RR) estimates for sewerage versus the other category. When a single study made two or more comparisons, we calculated a weighted average RR value, and used this value in our meta-analysis. We used the most adjusted RR estimate provided by the authors; if no adjusted estimate was available, we used the crude estimate. To obtain pooled-effect estimates, meta-analyses were done by use of an inverse variance method-ie, the study-specific adjusted log ORs for case-control and cross-sectional studies, and log RRs for cohort studies, were weighted by the inverse of their variance to compute a pooled RR with 95% CI.
25 studies investigated the association between sewerage and diarrhoea or related outcomes, including presence of intestinal nematodes. Pooled estimates show that sewerage systems typically reduce diarrhoea incidence by about 30% (RR 0.70, 95% CI 0.61-0.79), or perhaps as much as 60% when starting sanitation conditions are very poor. Studies with objective outcome measures showed even stronger pooled effect than studies that assessed diarrhoea incidence with interviews, while sensitivity analysis indicated that the effect remains even if we assume strong residual confounding.
Sewerage interventions seem to reduce the incidence of diarrhoea and related outcomes. However, we urge cautious interpretation of these findings, because, in many contexts, sewerage might be less cost effective and sustainable than onsite alternatives.
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发展中国家大多数城市的卫生设施不足，这对传染病负担有重大影响：在这种情况下，污水管道系统是一个合适的解决方案，还是应该集中精力开发基于现场解决方案的系统，如厕所？我们回顾了污水系统对腹泻病及相关结果的影响。由于到目前为止还没有随机对照试验，我们只纳入了观察性研究。
我们通过综合策略确定了相关研究，包括从 1966 年至 2010 年 2 月对 Medline 和其他数据库的搜索。在比较污水与其他卫生类别关系的研究中，我们使用了污水与其他类别相比的相对风险（RR）估计值。当一项研究进行了两次或更多次比较时，我们计算了加权平均 RR 值，并在荟萃分析中使用了该值。我们使用作者提供的最调整 RR 估计值；如果没有调整的估计值，我们就使用未调整的估计值。为了获得汇总效应估计值，我们使用了逆方差法进行荟萃分析，即病例对照和横断面研究的特定调整对数比值（OR），以及队列研究的对数 RR，用其方差的倒数加权，计算汇总 RR 及其 95%置信区间（CI）。
25 项研究调查了污水与腹泻或相关结果之间的关系，包括肠道线虫的存在。汇总估计表明，污水系统通常使腹泻发病率降低约 30%（RR 0.70，95%CI 0.61-0.79），或者在起始卫生条件非常差的情况下，发病率降低约 60%。采用客观结局指标的研究比采用访谈评估腹泻发病率的研究显示出更强的汇总效应，而敏感性分析表明，即使我们假设存在较强的残余混杂，该效应仍然存在。
污水干预措施似乎可以降低腹泻和相关结果的发生率。然而，我们敦促谨慎解释这些发现，因为在许多情况下，污水系统可能不如现场替代方案更具成本效益和可持续性。
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