An emergency-department study cannot establish a lethal postmortem cocaine cutoff simply by reporting concentrations in symptomatic patients. Zucoloto and colleagues studied 81 living adults and found that cocaine and cocaethylene concentrations did not provide a useful concentration-based relationship with clinical severity. The design did not evaluate autopsy specimens or validate a fatal threshold.
Who was selected, and when were samples collected?
The observational study enrolled patients with suspected cocaine or crack intoxication at a São Paulo hospital between December 2015 and March 2017. A positive urine cocaine screen was required. Of 84 initially assessed patients, three were excluded for other stimulant exposure, leaving 81. Most reported intranasal use; smoked crack and other routes also occurred. There was no controlled administered dose.
Blood and urine collection accompanied the initial clinical assessment. Approximately 3 mL blood was collected into EDTA tubes. The article does not specify a uniform anatomical blood-collection site or detailed storage conditions in this report. Time since last use was estimable in only 23 patients: mean 6.6 ± 5.1 hours, range 1–24. This timing uncertainty is material, not an incidental omission.
The urine screen did not measure blood cocaine
Urine screening used an immunoassay with a 150 ng/mL benzoylecgonine cutoff. Blood cocaine and cocaethylene were assessed separately using liquid-liquid extraction and HPLC with diode-array detection. The paper refers to an earlier method publication rather than reproducing a full numerical validation package. A reader should not assume a blood detection limit from the urine cutoff.
Cocaine was detected in blood in 20 of 81 patients. In that positive subset, the mean was 0.34 ± 0.45 μg/mL, with a range of 0.11–1.79 μg/mL. Cocaethylene was found in five patients, with a mean of 0.38 ± 0.34 μg/mL. These means describe detected subsets, not the entire cohort.
Severity was measured clinically, not inferred from a number
The Stimulant Intoxication Scale assessed vital signs, orientation and mental state. Seventy-four patients had mild scores, seven had moderate scores and none occupied the scale’s severe category. The observed score range was 0–13. The study therefore had limited coverage of severe toxicity and was not a fatal-case comparison.
Patients with chest pain had higher average cocaine and cocaethylene concentrations than those without chest pain, but neither comparison was statistically significant. Likewise, blood concentration differences between ethanol-positive and ethanol-negative groups were not significant. Higher averages should not be restated as proven concentration-response rules.
Why a death investigation needs a different inference
The authors concluded that measured concentrations did not prove useful for treatment or prognosis in this sample. That finding does not mean cocaine cannot cause serious harm. It means this study did not establish a reliable concentration-based severity classification.
There were no paired predeath and postmortem specimens, no autopsy-site comparisons and no decomposition experiment. It cannot estimate redistribution, a lethal threshold, a probability of death at a specified concentration, or the cause of an individual death. Its clinical participants also cannot be treated as a representative sample of all exposed people.
For forensic interpretation, separate the laboratory finding from the proposition being offered. A concentration in a living patient is evidence about that specimen and assessment context; applying it to autopsy blood requires additional evidence. Our review of hospital specimens in death investigations illustrates why collection timing and matrix must remain explicit.
Primary source
Zucoloto AD, Eller S, de Oliveira TF, Wagner GA, Fruchtengarten LVG, de Oliveira CDR, Yonamine M. Relationship between cocaine and cocaethylene blood concentration with the severity of clinical manifestations. American Journal of Emergency Medicine. 2021;50:404–408. doi:10.1016/j.ajem.2021.08.057.
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