Prevalence and factors associated with sputum smear negative tuberculosis among adult tb patients in Kawempe division-Kampala: a nested case control study.

Abstract

Smear microscopy has remained the most used test for diagnosis of tuberculosis in developing countries. However, there has been disproportionate increase in smear-negative tuberculosis. The objective of this study was to identify the prevalence and factors associated with smear-negative TB. Methods: A cross sectional and case control study designs were in Mulago hospital, CWRU-MU treatment center. The clinical, demographic and other variables were extracted from adult TB patients’ records, who were enrolled for treatment between 1st January 2002 and 31st December 2012 using a structured data extraction forms. Proportions and percentages were used to summarize categorical variables; and mean, median and standard deviation were used to summarize continuous variables. Bivariate and multivariate analyses (logistic regression) were used to identify clinical and socio-demographic features associated with smear-negative sputum. Result: The overall prevalence of sputum smear-negative was 9.1%, 15.5% among HIV positive (OR= 1.87, 95% CI =1.026-3.398) and 10.9% among those who had history of previous use of anti-biotic (OR =1.76, 95% CI=1.039-3.422). Prevalence among those who were 36 years and above was 10.3%. The duration between collection of sample and laboratory analysis, (OR=1.23, 95% CI= 1.001-1.519), had significant relationship with sputum smear-negative tuberculosis. Being HIV positive (OR1.87, 95% CI 1.026-3.398), having had history of previous use of antibiotic (OR 1.76, 95% CI 1.039-3.442) and the X-ray (OR =0.54, 95% CI=0.278-0.785) were significantly associated with sputum smear-negative TB. Conclusion: The prevalence of sputum smear-negative in this study was lower than the national level (26%). The sputum smear negative result was associated with HIV/AIDS and having history of previous use of antibiotic prior to sputum smear test. HIV positive TB patients were almost two ix

times more likely to have sputum smear-negative compared to HIV negative TB patients. Having had history of antibiotic use was almost twice more likely to give sputum smear-negative test result compared to those who never used antibiotic before the sputum smear.