Comparison of Hearing Thresholds among Patients on Treatment for Drug-Resistant Versus Drug-Susceptible Pulmonary Tuberculosis in A SubSaharan African Healthcare Setting

Abstract

Background: Pulmonary tuberculosis is a debilitating infectious disease that affects all age groups and sadly, a leading cause of death in developing countries particularly in sub-Saharan Africa. One major challenge facing the global efforts against tuberculosis is drug-resistance, which necessitates the use of aminoglycoside-based second line drugs that are known to have ototoxic potentials. Hearing impairment can be a source of social distress, professional disability and in some cases, litigation. This research compared the pure tone audiometric patterns of patients on treatment for drug-resistant versus drug-susceptible pulmonary tuberculosis. The incidence of hearing loss between the groups was assessed. Patients and Method: The research was a prospective comparative study of all eligible newly diagnosed pulmonary tuberculosis patients admitted into the Pulmonology unit of Federal Medical Centre, Owerri, Nigeria. Pre-treatment (baseline) and monthly pure tone audiometry was done for each patient before and during treatment respectively. The patients were followed up and assessed for three months. Data collected was analyzed with Statistical Package for Social Sciences (SPSS) version 20.0 software for Windows. Statistical significance was set at p< 0.05. Results: A total of 76 patients (38 in each group) completed the study. The M:F ratio was 1.53:1 and 1.24:1 for the drug resistant and drug susceptible groups respectively while the mean duration of presenting symptoms were 11.7 ± 7.8 and 7.4 ± 5.1 weeks for the groups respectively. The prevalence of baseline hearing impairment was 73.7% among both groups while by the third month it was 89.5% among the dug-resistant group and 78.9% among the drug-susceptible group implying a cumulative incidence of hearing loss of 15.8% and 5.3% respectively over three months. This difference was statistically significant. Conclusion: The incidence of hearing impairment among patients on treatment for drug-resistant pulmonary tuberculosis was approximately three-fold higher than their drug susceptible counterparts after three months of treatment; this was statistically significant.