Prevalence of early onsent sensorineural hearing loss following treatment of Nasopharyngeal carcinoma at the Kenyatta National Hospital
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BACKGROUND: High dose radiotherapy combined with chemotherapy has resulted in improved overall survival, yet little is known of the synergistic ototoxic effects of these agents. This study therefore, aimed at analysis the prevalence and pattern of sensorineural hearing loss after treatment of nasopharyngeal carcinoma at the Kenyatta National Hospital. Study design: prospective cross-sectional study. Materials and methods: Between 21st October 2010 to 10th April 2011, a total of 40 patients, were serially recruited from Kenyatta National Hospital ENT clinic and Cancer treatment centre (CTC). Pure-tone audiogram assessments were performed before treatment and immediately after treatment. The effects of concurrent chemotherapy and -radiotherapy were analysed. Data analysis: Data was entered into a customized MS access database. The characteristics of the patients were tabulated. Graphical tools were used to show patients with hearing loss before and after treatment. Estimates of prevalence and the 95% confidence intervals were calculated using STATA'S 'proportion' command. Result: 160 audio grams were included in this analysis, with each ear treated as an independent case. Conductive hearing loss was the main type of pre-treatment hearing loss with a prevalence of 68.0%, while prevalence of post-treatment sensorineural hearing loss was 64.0%%. The difference in prevalence of hearing loss before and after treatment was 15% (95% Cl, 0.9, 29.1), and this was statistically significant (p=0.043). There was strong evidence suggesting that the odds of developing hearing loss increased linearly with increase in the stage of the tumour, gender and the degree of pre-treatment hearing loss. CONCLUSION: Due to the high prevalence of post-treatment hearing loss, we do need to counsel the patients of this disabling side effect. There is need to use alternative modes of therapy such as linear accelerators or other chemotherapeutic agents that are known to be less ototoxic.