Population surveys compared with wastewater analysis for monitoring illicit drug consumption in Italy in 2010-2014

Background: Monitoring consumption by population surveys (PS) is an important way to challenge the spread of illicit drugs (ID). To improve the information, we explored a complementary method, particularly wastewater analysis (WWA). Methods: We estimated the prevalence of use by PS, and the consumption by WWA, of cocaine, opioids, cannabis, methamphetamine and MDMA (ecstasy) from 2010 to 2014 in Italy and compared the results. Results: According to PS, cannabis and cocaine were the ID most used in Italy (last month prevalence 3.0% and 0.43% respectively in 2010) followed by opioids (0.17%) and amphetamines (0.14%). WWA gave similar findings, with cannabis consumption (4.35 g THC/day/1000 inhabitants) exceeding cocaine (0.78 g), heroin (0.092 g), methamphetamine and MDMA (0.103 g). The time trend investigated by PS showed significant decreases for all ID from 2010 to 2012. WWA also indicated a reduction of consumption for methamphetamine (p