Method Consolidation to Improve Scope and Efficiency in Postmortem Toxicology

Abstract

Systematic toxicological approaches that employ both ideology changes and improvements in instrumentation and sample extraction allow for improved toxicology testing efficiency through lower sensitivities, higher specificity and minimized resource use. Historically, the San Francisco Office of the Chief Medical Examiner relied heavily on a gas chromatography mass spectrometry (GC–MS) testing regime, comprised of individual drug-class confirmation and quantitation assays. Traditional methods utilizing GC–MS typically require iterations of testing, exhausting sample volume, and hindering productivity and turnaround times, particularly for polypharmacy cases frequently seen in modern postmortem toxicology. The method described here consolidated the scope of seven legacy methods into a single liquid chromatography tandem mass spectrometry (LC–MS/MS) method for better sensitivity, higher throughput, minimal sample consumption for the quantitation of drugs of abuse and improved quality assurance with the incorporation of smart, automated processing. About 100 μL of blood or urine were rapidly extracted using a simple acetonitrile protein crash and subsequent in-vial filtration and injected on to an LC–MS-MS system. The developed method was fully validated to SWGTOX and international guidelines and incorporated 55 analytes along with a customized query that facilitates rapid and consistent application of acceptability criteria for data processing and review. Applicability was demonstrated with the analysis of 1,389 samples (858 blood and 531 urine) where at least 41% of positive results may have been missed due to their decreased sensitivity and 11% of results were not within the scope of the previous analytical methods estimated. On average, cases in this study would have previously required three distinct GC–MS assays, 3 mL of blood, and upwards of 30 h of active staff time. The described LC–MS-MS analytical approach has mitigated the need to perform multiple assays, utilized only 0.1 mL of sample, significantly reduced analyst work time, incorporated 10 additional analytes and allowed for a more comprehensive testing regime to better inform cause of death determinations.

Drug Overdose Deaths Before and After Shelter-in-Place Orders During the COVID-19 Pandemic in San Francisco

“…Demographic and toxicological outcomes were identified from forensic findings; cause-of-death determination methods have been previously published. 3,4 Housing information was collected from OCME investigations and analyzed using a county-level database of social service interactions. We compared overdose death features using χ 2 tests and calculated normalized death rates using postpandemic overdose deaths and 2019 US Census Bureau data.…”

Opioid Overdose–Related Emergency Department Visits and Accidental Deaths during the COVID-19 Pandemic

“…For the purposes of this study, demographic and toxicological information were collected on each case. Using a previously published method, accidental overdose deaths with fentanyl, norfentanyl, 6-monoacetylmorphine (6-MAM, heroin's primary metabolite), morphine, and/or codeine detected in blood were captured to best determine their relevance in causation of drug toxicity [10]. Contribution of heroin to death was assessed following the model described by Stam et al [11].…”

Evaluation and applicability of Alere iCup DX 14 for rapid postmortem urine drug screening at autopsy

“…In resource‐poor forensic medicine and pathology situations, a demand for some application of such POC testing may persist. If the desirable outcome is shorter turnaround times, gains in both chemical analysis and processing power have yielded significant increases in overall efficiencies, scope, and reporting times, without sacrificing overall testing quality [8]. If POC testing is used to more quickly identify toxicology‐related deaths that screen positive, such that cases which screen negative are not submitted for further toxicology testing, the impact of false positives and false negatives in some of the most commonly detected drug classes cannot be underestimated.…”

“…The confirmation methods utilized during the routine forensic toxicological program of the OCME consisted of a combination of liquid chromatography–tandem mass spectrometry (LC‐MS/MS) and gas chromatography–mass spectrometry (GC‐MS) techniques. Method A monitors 55 target drugs and metabolites from classes including cocaine, amphetamines, opioids, and some acidic drugs by LC‐MS/MS [8]. Method B is utilized in the analysis of 29 benzodiazepines and metabolites by LC‐MS/MS.…”