OBJECTIVE: To develop a clinical prediction rule to identify patients who can be 
safely discharged one hour after the administration of naloxone for presumed 
opioid overdose.
METHODS: Patients who received naloxone for known or presumed opioid overdose 
were formally evaluated one hour later for multiple potential predictor 
variables. Patients were classified into two groups: those with adverse events 
within 24 hours and those without. Using classification and regression tree 
methodology, a decision rule was developed to predict safe discharge.
RESULTS: Clinical findings from 573 patients allowed us to develop a clinical 
prediction rule with a sensitivity of 99% (95% CI = 96% to 100%) and a 
specificity of 40% (95% CI = 36% to 45%). Patients with presumed opioid overdose 
can be safely discharged one hour after naloxone administration if they: 1) can 
mobilize as usual; 2) have oxygen saturation on room air of >92%; 3) have a 
respiratory rate >10 breaths/min and <20 breaths/min; 4) have a temperature of 
>35.0 degrees C and <37.5 degrees C; 5) have a heart rate >50 beats/min and <100 
beats/min; and 6) have a Glasgow Coma Scale score of 15.
CONCLUSIONS: This prediction rule for safe early discharge of patients with 
presumed opioid overdose performs well in this derivation set but requires 
validation followed by confirmation of safe implementation.