Sensorineural Hearing Loss and Its Relationship with Duration of Chelation Among Major β-Thalassemia Patients

Abstract

Introduction Thalassemia is a common genetic disorder worldwide, also occurring frequently in Karachi, Pakistan. Beta (β)-thalassemia major patients need repeated transfusions which cause iron overload. Patients are treated with chelating agents to reduce the high serum ferritin level and to decrease morbidity and mortality due to increased iron levels. This combined therapy also leads to some complications. One of them is the sensorineural hearing loss (SNHL). To date, no data is available in Pakistan regarding SNHL among major β-thalassemia patients on chelating therapy.  Methods A cross-sectional study was performed in collaboration with the Thalassemia Center and Dr. Ruth Pfau at the Department of Ear, Nose, and Throat, Civil Hospital, Karachi, Pakistan. The variable to detect hearing was pure tone air and bone conduction thresholds at the frequencies of 250 - 4,000 Hz. Clinical data, such as chelating agent dose, duration, and hearing status, were recorded. Demographic characteristics, like age, gender, height, and weight, were noted. The hemoglobin and serum ferritin levels of the subjects were also included. Results Forty-five percent of cases of thalassemia were suffering from SNHL. In the right ear, the Pearson correlation of chelating agent dose (mg) with SNHL was mildly positive and statistically significant (r = 0.261, p < 0.001), (r = 0.337, p < 0.001), (r = 0.198, p = 0.005), and (r = 0.207, p = 0.003) at the frequencies of 250, 500, 1,000, and 2,000 Hz, respectively, and the Pearson correlation of chelating agent used (in months) with SNHL was mildly positive and statistically significant (r = 0.232, p = 0.001), and (r = 0.301, p < 0.001) at frequencies 250 to 500 Hz, respectively. In the left ear, the Pearson correlation of chelating agent dose (mg) with SNHL was mildly positive and statistically significant, (r = 0.191, p = 0.007), (r = 0.202, p = 0.004), (r = 0.297, p < 0.001), (r = 0.183, p = 0.010) and (r = 0.221, p = 0.002) at frequencies 250, 500, 1,000, 2,000, and 4,000 Hz, respectively, and Pearson correlation of chelating agent used (months) with SNHL was mildly positive and statistically significant only at the frequency of 2,000 Hz (r = 140, p = 0.049).  Conclusion Chelation therapy and regular blood transfusions, apart from prolonging the life of thalassemic patients, also leads to some complications. With this survey, it was concluded that almost half of the patients had normal hearing, while the other half had sensorineural hearing loss after the use of deferasirox. It is inferred that the incidence of SNHL is not only dose-related but the duration of use of a chelating agent is also a contributing factor.