Predictors of major toxicity after theophylline overdose

* Objective: To identify patients at high risk for major toxicity after theophylline intoxication who might benefit from early charcoal hemoperfusion. * Design: A 67-month prospective study. * Setting: Massachusetts Poison Control System. * Patients: 249 consecutive patients referred after theophylline intoxication (defined by a peak serum theophylline concentration [greater than or equal to] 167 [mu]mol/L [30 mg/L]). * Interventions: Uniform, protocol-directed management recommendations. * Main Outcome Measures: Identification of risk factors for major toxicity. * Results: 119 patients (48%) not receiving theophylline therapy had acute intoxication; among those receiving such therapy, 92 (37%) had theophylline intoxication because of chronic overmedication and 38 (15%) had acute intoxication. Major toxicity developed in 62 patients (25%); 13 patients (5%) died. Major toxicity was more common in patients with intoxication due to chronic overmedication than in those with acute intoxication who were not receiving theophylline therapy (49% compared with 10%, risk ratio, 4.85; 95% Cl, 2.96 to 7.94), even though the former group had lower peak serum theophylline concentrations (283 [mu]mol/L compared with 777 [mu]mol/L, P = 0.001). Logistic regression analysis identified two major factors associated with the development of major toxicity: 1) peak serum theophylline concentrations in cases of acute intoxication and 2) patient age in cases of chronic overmedication. Receiver-operating characteristic curve analysis indicated that major toxicity occurred in patients with a peak serum theophylline concentration of greater than 555 [mu]mol/L (100 mg/L) after acute intoxication and in patients older than 60 years (regardless of peak serum theophylline concentration) after chronic overmedication. * Conclusions: Predictors for major toxicity after theophylline intoxication differ by type of overdose.
Asthma patients over 60 years old who have been overmedicated with theophylline may be as risk for major toxicity. In patients who have a sudden episode of theophylline poisoning, a high blood concentration of theophylline may indicate major toxicity. Theophylline is a bronchodilator used to treat asthma. Of 254 patients, 119 had sudden theophylline poisoning but were not receiving theophylline therapy, 92 had chronic poisoning due to overmedication and 38 had sudden poisoning while receiving therapy. Forty-five overmedicated patients, 12 patients not receiving therapy and five patients receiving therapy developed major toxicity. Of these patients, the chronically overmedicated patients and the patients poisoned while receiving therapy were older than their counterparts who remained healthy, but had no other differences. The 12 theophylline-poisoned patients who were not receiving therapy had higher blood theophylline levels than those who did not develop toxicity.