Ambient temperature and mortality from unintentional cocaine overdose

Context.-Hot weather taxes cardiovascular function and is associated with increased deaths from heart disease. Cocaine can cause hypertension, tachycardia, coronary vasospasm, arrhythmias, and increased core temperature. Objective.-To determine the association between mortality from cocaine overdose and hot weather. Setting.-New York, NY. Design.-Retrospective review of medical examiner cases from 1990 through 1995. Subjects.-All fatal unintentional cocaine overdoses from 1990 through 1992 (n=1382) and all hyperthermia deaths of cocaine users (n = 10) were used to identify a maximum daily temperature threshold above which mortality from cocaine intoxication increased. The study population consisted of all fatal unintentional cocaine overdoses from 1993 through 1995 (n = 2008) and 4 contemporaneous comparison groups that included fatal unintentional opiate overdoses (n = 793), all other fatal unintentional overdoses (n = 85), and a subset of homicides (n = 4638) and fatalities from motor vehicle crashes (n = 815). Main Outcome Measures.-The number of overdose deaths and the proportion of homicides and traffic fatalities with a positive cocaine toxicology test result on days with a maximum temperature above or below the temperature threshold. Results.-A threshold temperature of 31.1 degrees C (88 degrees F) was identified, above which the mean daily number of fatal cocaine overdoses increased steadily. On days with a maximum daily temperature of 31.1 degrees C (88 degrees F) or higher ("hot days"), the mean daily number of cocaine overdose deaths was 2.34 (SD = 1.68), which was 33% higher than the mean on days with a maximum temperature of less than 31.1 degrees C (88 degrees F) (mean=1.76 [SD=1.37] (P<.001). In contrast, the mean number of opiate overdose deaths per day was 0.81 (SD = 0.94) on hot days and 0.71 (SD = 0.86) on other days (P=.28). For other drug overdose deaths, the mean number of deaths per day was 0.08 (SD = 0.28) on hot days and 0.08 (SD = 0.28) on other days (P=.69). Among homicides, the proportion with a positive cocaine toxicology test result was 18.9% on hot days and 19.5% on other days (P=.69), and among traffic fatalities, the proportions with positive cocaine toxicology test results were 9.5% on hot days and 10.3% on other days (P=.91). Conclusions.-High ambient temperature is associated with a significant increase in mortality from cocaine overdose. Based on our comparison groups, the increase is not explained by changes in cocaine use among the general population. Although cocaine use is dangerous on all days, it appears to be even more dangerous on hot days.