Written by Clay Smith
Emergency physicians were not accurate in clinically diagnosing gamma-hydroxybutyrate (GHB) intoxication. A rapid test is needed.
Why does this matter?
GHB may be used by an individual or used as a rapid depressant to render a victim unconscious. It has been implicated in “date rape” scenarios. Patients have profound CNS depression and are comatose. But they can awaken within minutes. If you’ve never seen it, it’s really weird. There aren’t too many drugs like it. But rapid urine drug screens don’t detect it, and definitive diagnosis requires gas chromatography (GC). GHB abuse is less common in the U.S. but is more prevalent in some European countries. How good are we at recognizing and diagnosing GHB toxicity?
GHB – from coma to asking for a sandwich in 5 minutes
Altered patients with suspected drug intoxication who had a urine toxicology screen ordered were prospectively enrolled, and emergency physicians recorded what they thought was the most likely diagnosis up front. Drug and alcohol testing was at the discretion of the physician. All urine samples had GC performed to determine if GHB was present or not. GC results were not available at the time of treatment. Of 506 cases, GHB was present at a surprisingly high rate, 100 patients (~20% prevalence). What are people doing in Amsterdam? Don’t answer that… Most were male, and 35% had other substances present on drug screening. Median GCS for those who eventually tested positive for GHB was much lower (GCS = 3) than those who tested negative (GCS = 11). The diagnostic accuracy of clinical assessment for GHB compared with GC wasn’t great: sensitivity 63% (95%CI 52-73); specificity 93% (90-95); positive predictive value 67% (60-77); negative predictive value 92% (88-94). The punch line is – we can’t tell which altered patients are due to GHB, and a rapid test is needed to potentially avoid invasive procedures and extensive workup on such patients. But wait – a big caveat – even if we had a rapid test, a positive result may indicate past use but not present toxicity. And even if it was fairly rapid, we can’t sit on patients with a GCS of 3 and not do something. So, most patients would still get a big workup. Bear in mind, this is a very high prevalence. Personally, I haven’t seen many GHB cases (at least that I know of). This may not be generalizable to lower prevalence settings (i.e. much of planet earth).
Can emergency department clinicians diagnose gamma-hydroxybutyrate (GHB) intoxication based on clinical observations alone? Emerg Med J. 2021 Mar 5;emermed-2020-209577. doi: 10.1136/emermed-2020-209577. Online ahead of print.