Testing urban wastewater to assess compliance with prescription data through wastewater-based epidemiology: First case study in Italy.

Sub-optimal adherence to pharmacological therapy is one of the main reasons for poor effectiveness, reducing the patient's quality of life and affecting health-care economics. This study investigated the possibility for a wastewater-based epidemiology approach to assess the overall adherence of a population to some pharmacological therapies in a defined area. We selected specific active ingredients and their main urinary metabolites (biomarkers) according to the best practice protocol available and we measured them for the first time in urban wastewater. We conducted this first case study in Italy, considering the whole country and two Italian regions by sampling for five days six cities from north to south. Liquid chromatography tandem mass spectrometry was used to measure the biomarkers in raw wastewater, developing and validating specific analytical methods. We used concentrations measured in influent wastewater, together with a careful review of the excretion profile of the active ingredients selected, to back-calculate consumption (measured consumptions - MC) which were then compared with consumptions calculated from medical prescriptions (expected consumptions - EC) reported annually by the Italian Medicine Agency. In general there was a rough correlation between MC and EC, with ratios sometimes close to unity and always within a 0.3-3.0 range. Interpretation of the results suffers some biases, which are case-by-case discussed in detail, but inclusion of measurements of the urinary metabolites together with the active ingredients gave a fuller understanding of the results.