Association between life-threatening cocaine toxicity and plasma cholinesterase activity.

STUDY OBJECTIVE To determine whether plasma cholinesterase (pseudocholinesterase) activity is a marker for severe cocaine toxicity. DESIGN A prevalence study in a cohort of cocaine users. SETTING A large urban emergency department. PARTICIPANTS During a three-month period in 1989, 187 patients who presented to the ED on 191 consecutive occasions with signs and symptoms consistent with cocaine intoxication were prospectively enrolled in the study protocol. METHODS AND MEASUREMENTS All patients had plasma cholinesterase activity determined by the electrometric method. The patients who were cocaine positive were stratified into one of two groups: life-threatening toxicity (LT) and non-life-threatening toxicity (NLT), based on a predetermined set of criteria. Cocaine-negative patients served as controls for the LT group if criteria were otherwise met. RESULTS Mean (+/- SD) plasma cholinesterase activities for the LT, NLT, and control groups were 682 +/- 277, 904 +/- 279, and 1,058 +/- 385 Michel units/L, respectively. All three groups were significantly different from each other (P less than .05 by analysis of variance). CONCLUSION The data suggest that decreased plasma cholinesterase activity is associated with increased risk of life-threatening cocaine toxicity.