The impact of rural residence and HIV infection on poor tuberculosis treatment outcomes in a large urban hospital: a retrospective cohort analysis

BACKGROUND Successful tuberculosis (TB) treatment is essential to effective TB control. TB-HIV coinfection, social determinants and access to services influenced by rural residence can affect treatment outcome. We examined the separate and joint effects of rural residence and HIV infection on poor treatment outcome among patients enrolled in a large TB treatment centre in Kano, Nigeria. METHODS We retrospectively analysed a cohort of patients with TB enrolled in a large urban TB clinic in northern Nigeria, from January 2010 to December 2014. Poor treatment outcome was defined as death, default or treatment failure. We used Poisson regression to model rates and determine the relative risks (and 95% confidence intervals, CI) of poor treatment outcomes. RESULTS Among 1381 patients included in the analysis, 28.4% were rural residents; 39.8% were HIV-positive; and 46.1% had a poor treatment outcome. Approximately 65 and 38% of rural and urban residents, respectively, had a poor treatment outcome. Rural residents had 2.74 times (95% CI: 2.27-3.29) the risk of having a poor treatment outcome compared to urban residents. HIV-positive patients had 1.4 times (95% CI: 1.16-1.69) the risk of poor treatment outcome compared to HIV-negative patients. The proportion of poor treatment outcome attributable to rural residence (population attributable fraction, PAF) was 25.6%. The PAF for HIV infection was 11.9%. The effect of rural residence on poor treatment outcome among HIV-negative patients (aRR:4.07; 95%CI:3.15-5.25) was more than twice that among HIV-positive patients (aRR:1.99; 95%CI:1.49-2.64). CONCLUSION Rural residents attending a large Nigerian TB clinic are at increased risk of having poor treatment outcomes, and this risk is amplified among those that are HIV-negative. Our findings indicate that rural coverage of HIV services may be better than TB services. These findings highlight the importance of expanding coverage of TB services to ensure prompt diagnosis and commencement of treatment, especially among rural-dwellers in resource-limited settings.