Urine drug screen co-positivity and the fentanyl testing gap among adult psychiatric emergency department encounters in West Virginia: a cross-sectional analysis

Background Traditional opiate immunoassays do not reliably detect fentanyl, and patterns of presumptive drug co-positivity in psychiatric emergency care remain poorly characterized.Objectives To describe class-specific urine drug screen positivity, quantify co-positivity among explicitly co-tested encounters, and assess the fentanyl testing gap among adult psychiatric emergency department encounters at two hospitals in West Virginia.Methods We retrospectively analyzed 1,091 adult psychiatric emergency department encounters at two West Virginia hospitals from October 2020 through December 2024. Testing was clinician-directed. Class-specific estimates used only encounters tested for each class. Six-core-class co-positivity was assessed among 281 complete-panel encounters; complete and incomplete panels were compared. Multivariable logistic regression evaluated fentanyl and amphetamine/methamphetamine co-positivity among 350 co-tested encounters.Results Among tested encounters, tetrahydrocannabinol was positive in 214 of 513 (41.7%), amphetamine/methamphetamine in 203 of 509 (39.9%), and fentanyl in 146 of 519 (28.1%). Among complete-panel encounters, 128 of 281 (45.6%) were positive for at least two core classes. Substance-related chief complaints were more common among complete-panel encounters than among incomplete-panel encounters (73.3% versus 56.8%; p < .001). Among fentanyl-positive encounters co-tested for amphetamine/methamphetamine, 81 of 108 (75.0%) were also positive for amphetamine/methamphetamine. Amphetamine/methamphetamine positivity was associated with fentanyl positivity (adjusted odds ratio, 8.5; 95% confidence interval, 4.8–14.9). Among 118 fentanyl-positive encounters co-tested using the traditional opiate assay, 91 (77.1%) were opiate-screen-negative.Conclusions Fentanyl and amphetamine/methamphetamine screens frequently overlapped in clinically selected subsets, and traditional opiate screening missed most fentanyl-positive screens. Psychiatric emergency services in fentanyl-affected regions should evaluate fentanyl-specific testing. Because immunoassays were presumptive and testing was nonprotocolized, findings represent screening yield, not confirmed exposure or population prevalence.