Comparison of Patient Questionnaires and Plasma Assays in Intentional Drug Overdoses

Abstract

Our aim was to explore the agreement between clinically collected information on purported drug intake and plasma data in intentional drug overdose. We included all subjects with intentional drug overdose above 15 years of age consecutively admitted to the Emergency Department of the University Hospital during 4 months. Information about drugs used and sources of this information was collected and compared to presence of drug in plasma, concerning four drugs with high toxic potential (tricyclic antidepressants, meprobamate, paracetamol and ethanol). Sensitivity, specificity, predictive positive and negative values of all sources of information pooled were assessed for each drug. 413 intentional drug overdoses were included, 66% with more than one drug. According to clinical information, 8% took tricyclic antidepressants, 11% meprobamate, 9% paracetamol and 41% ethanol. Systematic plasma assays confirmed this in 59% of cases for tricyclic antidepressants, 76% for meprobamate and ethanol, and 77% for paracetamol. Plasma concentrations were considered toxic in 28% of cases for tricyclic antidepressants, 65% for meprobamate, 43% for ethanol and never for paracetamol. Tricyclic antidepressants and meprobamate were found unexpectedly in 3%, paracetamol in 7% and ethanol in 6%. Toxic concentrations were found only with meprobamate. The risk of erroneous, clinically collected information was greater by excess (25 to 40% false positives) than by lack (3 to 7% false negatives). Thus, the consequences of erroneous, clinically collected information were probably more excess cost for the institution than medical risk for the patients. However these results found at the population level may not be true at an individual level.

Part 12: Cardiac Arrest in Special Situations

“…Whenever possible, history gathering should include questioning of persons who accompany the patient, evaluation of containers, review of pharmacy records, and examination of the patient's prior medical record. 220 Many patients who ingest medications in a suicide attempt take more than 1 substance, and the number of substances ingested is greater in fatal than in nonfatal suicide attempts. 221 Comprehensive toxicology laboratory testing is virtually never available in a time frame that supports early resuscitation decisions.…”

Reliability of self-reported use of amphetamine, barbiturates, benzodiazepines, cannabinoids, cocaine, methadone, and opiates among acutely hospitalized elderly medical patients

“…In a Finish study, 16% of acutely hospitalised patients had a positive benzodiazepine screening whereof 33% admitted use (NPV=89%) (9). Patients presenting in emergency departments are considerably younger of age but have also been found to report substance use with intermediate sensitivity (4,15,17).…”

“…This especially happened for legal drugs (benzodiazepines, methadone and opiates) and may be explained by either exaggerated reporting (16,17) or more likely by pharmacokinetic circumstances due to fast elimination half lives of used drugs, diluted urine, etc. (10,15).…”

“…Undeclared drug use must be expected even more frequently outside a research setting where patients are not structurally interviewed or motivated by drug analysis (17). The diagnostic benefits of toxicologic screens must be held against the extra costs, workload and waiting time connected to additional analysis.…”

The profile of the overdose patient presenting at Paarl Hospital Emergency Department

“…Tricyclic antidepressants and paracetamol were found to be less commonly used in previous studies, while a higher frequency of simultaneous usage of alcohol was found. 5 The higher frequency of tricyclic antidepressants could be attributed to the fact that these drugs are old antidepressants that are not commonly used overseas, but commonly used in South Africa.…”