A cross-sectional analysis of fentanyl analog exposures among living patients.

: Synthetic opioids, including fentanyl analogs, contribute to an increasing proportion of opioid-related deaths. Highly potent analogs pose an increased risk for fatal overdose. The prevalence of fentanyl analog exposures in patients with known opioid exposure is unknown.: The purpose of this study was to determine the exposure prevalence for fentanyl analogs in living patients with positive urine screens for opiates or fentanyl.: This was a cross-sectional analysis of urine high performance liquid chromatography/tandem mass spectroscopy (HPLC-MS/MS) results from patients with a positive urine screen for opiates or fentanyl at a large public healthcare system in Chicago, Illinois. Samples with positive screens were non-continuously tested by HPLC-MS/MS for 5 selected months in 2018 and 2019.: A total of 219 urine samples which screened positive for fentanyl or opiates underwent HPLC-MS/MS testing. At least one fentanyl analog was detected in 65.3% (n = 143) of samples with 26.0% (n = 57) testing positive for multiple analogs. The most common analogs, intermediates, or metabolites were: 4-ANPP (n = 131); 2-furanylfentanyl (n = 22); acryl fentanyl (n = 21); butyrylfentanyl (n = 15); cyclopropylfentanyl (n = 15); and carfentanil (n = 13). Of samples which screened positive for fentanyl (n = 188), 70.2% (132) tested positive for at least one fentanyl analog. Of samples which screened negative for fentanyl but positive for opiates (n = 31), 35.5% (n = 11) tested positive for fentanyl analogs: Fentanyl analog exposure is common in patients with positive urine screens for fentanyl or opiates. Screening living patient samples for synthetic opioids has future toxicosurveillance implications and these data underscore the increased risks from illicit opioid use.