Sensorineural hearing loss in β-thalassemia patients treated with iron chelation

Abstract

The predictive value of pure-tone audiometry (PTA) in the early detection of ototoxicity has been questioned, particularly in the higher frequencies. Otoacoustic emissions testing appears to be more sensitive to cochlear insult than conventional PTA. We conducted a cross-sectional descriptive study to compare the efficacy of distortion-product otoacoustic emissions (DPOAE) testing with that of PTA as a method of audiologic monitoring. Our study group was made up of 159 patients (318 ears)-69 males (43.4%) and 90 females (56.6%), aged 5 to 61 years (mean: 23.59 ± 12.55). All patients had been diagnosed with either β-thalassemia major (BTM) or β-thalassemia intermedia (BTI), and all had received at least 1 year of treatment within the previous year with an iron chelator-either deferasirox, desferrioxamine (deferoxamine in the United States), deferiprone, or a combination of desferrioxamine and deferiprone. PTA and DPOAE evaluations were performed by the same audiologist using the same audiometer for all patients. In the right ears, the overall incidence of ototoxicity as manifested by sensorineural hearing loss was 39.0% on PTA and 22.0% on DPOAE testing; in the left ears, the corresponding figures were 27.7 and 19.5%, respectively. There were no statistically significant differences in the incidence of ototoxicity between the BTM and BTI groups with any of the four different drug regimens on PTA (p = 0.765, p = 0.378, p = 0.265, and p = 0.579, respectively) or on DPOAE testing (p = 0.890, p = 0.263, p = 0.390, and p = 0.340, respectively). Based on these data, we found no significant difference between PTA and DPOAE testing in their ability to detect ototoxicity. We conclude that periodic testing with both PTA and DPOAE is necessary for patients with suspected β-thalassemia in order arrive at a prompt diagnosis and initiate timely management.