Effect of cocaine use on bone marrow-mediated erythropoiesis.

OBJECTIVES: Cocaine-mediated erythrocytosis is one of several effects that cocaine may have on hematologic indices; however, the precise mechanism by which cocaine induces peripheral erythrocytosis is not fully understood. The objective of this study was to examine the contribution of the bone marrow to cocaine-mediated erythrocytosis. METHODS: Differences in mean hemoglobin concentration, hematocrit, and reticulocyte counts were measured in consecutive cocaine-exposed and cocaine-unexposed patients who presented to the emergency department (ED) with chest pain. Acute cocaine exposure (<3 hours) was confirmed by history and toxicologic analysis of the urine on all patients. Means were compared using independent-samples t-test and covariates were examined using multiple regression. RESULTS: Seventy-nine patients met enrollment criteria. Hemoglobin and hematocrit levels were significantly elevated in the cocaine-using subjects (13.5/39.8) compared with controls (12.6/37.7; p < 0.02). However, no corresponding elevation in reticulocyte count (p = 0.2) was observed. Multivariate logistic regression revealed that male chest pain patients were significantly more likely to be exposed to cocaine (OR 5.15 [95% CI = 1.77 to 15.3]) than females (p = 0.001), and all relative increases in hemoglobin concentration in the cocaine-exposed group were attributable to gender. Cocaine exposure was not significantly associated with reticulocyte count. Multivariate linear regression revealed that of demographic, medical, and substance use covariates, only a history of diabetes mellitus was significantly associated with an elevated reticulocyte count (p = 0.009). CONCLUSIONS: Acute cocaine exposure is not associated with erythrocytosis in younger ED patients with chest pain. The lack of an elevated reticulocyte count suggests that bone marrow does not contribute to any transient erythrocytosis that may occur.

Validation of a brief observation period for patients with cocaine-associated chest pain.

BACKGROUND: Retrospective studies of patients with cocaine-associated chest pain suggest that a strategy of discharging patients from the emergency department after a 12-hour observation period if they do not have evidence of ischemia should be associated with a very low rate of complications. METHODS: We prospectively evaluated the safety of a 9-to-12-hour observation period in patients with cocaine-associated chest pain who were at low-to-intermediate risk of cardiovascular events. Consecutive patients who reported or tested positive for cocaine use and who received protocol-driven care in a chest-pain observation unit were included. Patients who had normal levels of troponin I, without new ischemic changes on electrocardiography, and who had no cardiovascular complications (dysrhythmias, acute myocardial infarction, or recurrent symptoms) during the 9-to-12-hour observation period were discharged from the unit. The main outcome was death from cardiovascular causes at 30 days. RESULTS: Three hundred forty-four patients with cocaine-associated chest pain were evaluated. Forty-two of these patients (12 percent) were directly admitted to the hospital. The study cohort comprised the remaining 302 patients. During the 30-day follow-up period, none of the patients died of a cardiovascular event (0 percent; 95 percent confidence interval, 0 to 0.99), and only 4 of the 256 patients for whom detailed follow-up data were available had a nonfatal myocardial infarction (1.6 percent; 95 percent confidence interval, 0.1 to 3.1). All four nonfatal myocardial infarctions occurred in patients who continued to use cocaine. CONCLUSIONS: Patients with cocaine-associated chest pain who do not have evidence of ischemia or cardiovascular complications over a 9-to-12-hour period in a chest-pain observation unit have a very low risk of death or myocardial infarction during the 30 days after discharge.