audiological evaluation of patients taking kanamycin for multidrug resistant tuberculosis

introduction: the incidence of multidrug resistant tuberculosis is increasing in developing countries. aminoglycosides are an integral part of second-line drugs, however ototoxicity is a major limitation for their use. this study aims to determine the extent of hearing loss in patients taking one of the commonly prescribed drugs for multidrug resistant tuberculosis (mdr-tb), kanamycin, at a government medical college, patiala, punjab, india, which is a 1200 bed tertiary care hospital.  materials and methods: a total of 100 patients (68 males and 32 females) with confirmed diagnosis of mdr-tb were included in this study conducted between january 2012 and february 2014. subjects were between 15 to 60 years of age, with a mean age of 37.46 ± 10.1. pure tone audiometry (pta) was performed before the start of the therapy, as a baseline, and was repeated after 1 week and 6 weeks of kanamycin use to assess hearing loss as an effect of therapy.  results: of the 100 patients examined, ototoxicity was found in 18 subjects post therapy. incidence of high frequency hearing loss was 2% at week 1, and 12% after 6 weeks of follow up. however, 4% of the cases developed flat loss at week 6. the hearing loss was bilateral in 13 patients and unilateral in 5 patients. ototoxicity was more common in males (66.67%) compared to females (33.3%). maximum cases were found in the age group of 36 to 45 years (36.8%), the majority being from a rural background (83.3%). the association with socioeconomic status (p=0.024) and co-morbid conditions like diabetes and hypertension (p=0.001) reached statistical significance.  conclusion:  lack of specific guidelines to monitor patients taking aminoglycosides makes ototoxicity a major adverse effect of their use in mdr-tb. more studies are mandated to study the risk factors associated with the development of ototoxicity and for the development of alternate drugs for the treatment of mdr-tb.