Objectives: Gamma-hydroxybutyrate (GHB) is a drug of abuse with central depressing effects, which may cause coma with a GCS score as low as 3. A rapid diagnosis 'GHB intoxication' may prevent unnecessary diagnostic work-up and may lead to guided, less invasive, treatment. The aim of this study was to evaluate if ED physicians' clinical evaluation were sufficient for diagnosis in patients with suspected GHB-intoxication.
Methods: Patients presenting at the ED with a GCS<15 and a potential intoxication with drugs of abuse for whom urine toxicology screen was performed were included consecutively. After a first assessment, the ED physician registered the most likely initial diagnosis in the hospital information system. Urine of these patients was tested with a validated gas chromatography analytical method for GHB (confirmation test). The initial diagnoses were compared for agreement with the results of the confirmation test.
Results: A total of 506 patients were included, 100 patients tested positive for GHB and 406 patients tested negative for GHB. Sensitivity and specificity of the ED physicians compared with the confirmation test to diagnose GHB intoxications were 63% (95% CI 52 to 73) and 93% (95% CI 90 to 95), respectively. The positive predictive value was 67% (95% CI 60 to 77) and the negative predictive value was 92% (95% CI 88 to 94).
Conclusion: Physicians underestimate the presence of GHB intoxication and can fail to diagnose GHB intoxication based on clinical observations alone. In the future, a rapid reliable initial analytical GHB test in addition to clinical judgement could be valuable to reduce false negative diagnosis.
Keywords: clinical assessment; diagnosis; drug abuse; poisoning; toxicology.
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