Evaluation of the incidence of sensorineural hearing loss in beta-thalassemia major patients under regular chelation therapy with desferrioxamine.

With the improved life expectancy of beta-thalassemia major patients, new clinical problems, such as hearing loss, must be evaluated. To determine the incidence of sensorineural hearing loss and its relationship to desferrioxamine (DFO), 128 patients receiving subcutaneous DFO in doses from 21 to 39 mg/kg/day were studied. These patients had received their total weekly dose of DFO according to two different methods. The first group (QOD group of 52%) had received it on an every other day basis. The second group (QD group of 48%) had received it on 6 days a week. Otological examinations and pure tone audiometry were performed on the patients as they routinely visited Shiraz Cooley's Center, to find a possible correlation between the dose and duration of therapy. 56 patients (44%) in both groups had no evidence of drug-induced auditory abnormalities. Of the patients in the QOD group 44.7% had hearing loss in the right ear and 41.8% in the left ear at a frequency of 8,000 Hz compared to the QD group, 27.8 and 23%, respectively (with p < 0.047 and p < 0.02, respectively). No correlation was found between the duration of DFO therapy and sensorineural deficit. A significant correlation was found between the dose of drug given at each episode of DFO therapy and hearing loss at the frequency of 8,000 Hz, when comparing the QOD group with the QD group. Hence, it may be concluded that DFO ototoxicity is determined not only by the total amount of the drug given, but also by its maximal plasma concentration. Thus we suggest periodical audiologic checkups and a low dosage of DFO (below 50 mg/kg/day) given on at least 5-6 days a week for the prevention and prompt diagnosis of audiologic complications.