Monitoring Injected Drug Use in Greece Through Syringe Residue Analysis: A Multicity Study Within the ESCAPE Network

This study presents findings from the European Syringe Collection and Analysis Project Enterprise (ESCAPE) conducted in Greece between 2022 and 2024. Used syringes were collected through harm reduction services and needle distribution and collection programs coordinated by EOPAE in Athens, Thessaloniki, and Patras, and analyzed using standardized ESCAPE extraction procedures followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A total of 2122 syringes were included in the study. Substantial geographical variability in injected drug-use patterns was identified across the participating cities. Athens demonstrated persistent opioid predominance accompanied by high cocaine co-detection, extensive adulteration, and frequent multiple drug co-detections. Methamphetamine was detected exclusively in Athens, demonstrating a transient increase during 2023. Thessaloniki exhibited a progressively cocaine-dominant profile, with cocaine detections increasing markedly during the study period, while opioids remained consistently prevalent. In contrast, Patras demonstrated a distinct buprenorphine-centered profile associated with comparatively lower adulteration prevalence and fewer multiple drug category co-detections. Increasing detections of benzodiazepines, methadone, and pregabalin were observed across all cities during 2024. Fentanyl was detected in all participating cities during the final study year, although prevalence remained low. Adulterants, including caffeine and paracetamol, were highly prevalent in Athens and Thessaloniki but substantially less frequent in Patras. The present findings demonstrate substantial regional heterogeneity in injected drug-use patterns within Greece and support syringe residue analysis as a rapid and highly informative surveillance approach capable of identifying temporal drug-market changes, emerging synthetic opioids, adulteration patterns, and evolving patterns of injected drug use.