Abstract：
BACKGROUND: Wastewater-based epidemiology (WBE) has emerged as a timely, non-invasive, and cost-effective indicator of illicit drug consumption. It is increasingly used by international organizations as a proxy measure for estimates of drug prevalence and related trends. Nevertheless, the literature exploring the limitations of WBE remains limited. This paper aims to shed further light on important shortcomings of WBE with recommendations on moving forward.
METHODS: Utilizing case study and statistical analysis, the paper critically reviews methodological challenges associated with WBE results related to (i) levels, (ii) trends, and (iii) between-city comparisons of drug use. Data from raw influent wastewater samples from wastewater plants in the cities of Oslo, Bergen and Stavanger/Sandnes were analysed for amphetamine, methamphetamine, MDMA, and cocaine (benzoylecgonine) over a 3-year period. Normalized population loads were calculated and variation in daily loads analysed with plots and estimation of means, confidence intervals, and coefficient of variation. Linear regression models examined trends and between-city differences.
RESULTS: Plots and statistical analyses revealed extensive variation in daily loads, with min/max values of 6.1/453.9 mg/day per 1,000 inhabitants 15-64 years for amphetamine and correspondingly 9.4/675.9 mg for methamphetamine. Substantial differences in load levels and patterns across time and plants were also observed. A carefully designed sampling procedure and a relatively large number of daily samples are required to obtain estimates of sufficient precision for determining trends in space or time. Cross-referencing with alternative trend variables can improve the interpretation of WBE trend indicators. Finally, when using mean load levels for different wastewater-treatment plants to assess spatial variation in drug use, the representativeness of the catchment area should be evaluated before interpreting observed changes as city differences.
CONCLUSIONS: Although WBE is a useful supplementary indicator of illicit drug consumption, important methodological issues and potential shortcomings should be taken into account when designing sampling procedures and interpreting the analytical results.
METHODS: Utilizing case study and statistical analysis, the paper critically reviews methodological challenges associated with WBE results related to (i) levels, (ii) trends, and (iii) between-city comparisons of drug use. Data from raw influent wastewater samples from wastewater plants in the cities of Oslo, Bergen and Stavanger/Sandnes were analysed for amphetamine, methamphetamine, MDMA, and cocaine (benzoylecgonine) over a 3-year period. Normalized population loads were calculated and variation in daily loads analysed with plots and estimation of means, confidence intervals, and coefficient of variation. Linear regression models examined trends and between-city differences.
RESULTS: Plots and statistical analyses revealed extensive variation in daily loads, with min/max values of 6.1/453.9 mg/day per 1,000 inhabitants 15-64 years for amphetamine and correspondingly 9.4/675.9 mg for methamphetamine. Substantial differences in load levels and patterns across time and plants were also observed. A carefully designed sampling procedure and a relatively large number of daily samples are required to obtain estimates of sufficient precision for determining trends in space or time. Cross-referencing with alternative trend variables can improve the interpretation of WBE trend indicators. Finally, when using mean load levels for different wastewater-treatment plants to assess spatial variation in drug use, the representativeness of the catchment area should be evaluated before interpreting observed changes as city differences.
CONCLUSIONS: Although WBE is a useful supplementary indicator of illicit drug consumption, important methodological issues and potential shortcomings should be taken into account when designing sampling procedures and interpreting the analytical results.
摘要：
背景：基于废水的流行病学（WBE）应运而生，非侵入性，和非法药物消费的成本效益指标。国际组织越来越多地将其用作估计毒品流行率和相关趋势的替代措施。然而，探索WBE局限性的文献仍然有限。本文旨在进一步阐明WBE的重要缺点，并提出前进的建议。
方法：利用案例研究和统计分析，本文批判性地回顾了与(I)级别相关的WBE结果相关的方法学挑战，(二)趋势,和(iii)药物使用的城市间比较。来自奥斯陆城市污水处理厂的原始进水废水样本的数据，对卑尔根和斯塔万格/桑德尼斯进行了苯丙胺分析，甲基苯丙胺,MDMA,和可卡因（苯甲酰秋葵碱）超过3年。计算了归一化的人口负荷，并通过地块和均值估算分析了日负荷的变化，置信区间，和变异系数。线性回归模型检验了趋势和城市之间的差异。
结果：图表和统计分析揭示了每日负荷的广泛变化，苯丙胺的最小/最大值为6.1/453.9毫克/天/每1,000居民15-64岁，甲基苯丙胺的最小/最大值为9.4/675.9毫克。还观察到跨时间和植物的负荷水平和模式的实质性差异。需要精心设计的抽样程序和相对大量的每日样本，才能获得足够精确的估计，以确定空间或时间的趋势。与替代趋势变量的交叉引用可以改善对WBE趋势指标的解释。最后,当使用不同污水处理厂的平均负荷水平来评估药物使用的空间变化时，在将观察到的变化解释为城市差异之前，应评估集水区的代表性。
结论：尽管WBE是非法药物消费的有用补充指标，在设计抽样程序和解释分析结果时，应考虑重要的方法学问题和潜在的缺陷。
方法：利用案例研究和统计分析，本文批判性地回顾了与(I)级别相关的WBE结果相关的方法学挑战，(二)趋势,和(iii)药物使用的城市间比较。来自奥斯陆城市污水处理厂的原始进水废水样本的数据，对卑尔根和斯塔万格/桑德尼斯进行了苯丙胺分析，甲基苯丙胺,MDMA,和可卡因（苯甲酰秋葵碱）超过3年。计算了归一化的人口负荷，并通过地块和均值估算分析了日负荷的变化，置信区间，和变异系数。线性回归模型检验了趋势和城市之间的差异。
结果：图表和统计分析揭示了每日负荷的广泛变化，苯丙胺的最小/最大值为6.1/453.9毫克/天/每1,000居民15-64岁，甲基苯丙胺的最小/最大值为9.4/675.9毫克。还观察到跨时间和植物的负荷水平和模式的实质性差异。需要精心设计的抽样程序和相对大量的每日样本，才能获得足够精确的估计，以确定空间或时间的趋势。与替代趋势变量的交叉引用可以改善对WBE趋势指标的解释。最后,当使用不同污水处理厂的平均负荷水平来评估药物使用的空间变化时，在将观察到的变化解释为城市差异之前，应评估集水区的代表性。
结论：尽管WBE是非法药物消费的有用补充指标，在设计抽样程序和解释分析结果时，应考虑重要的方法学问题和潜在的缺陷。
