1.4 Prognosis

TB is a severe disease, often fatal if left untreated. After 10 years without treatment, the case fatality rate (CFR) is estimated at 70% for smear-positive PTB and 20% for smear-negative, culture-positive PTB [1] Citation 1. Tiemersma EW, van der Werf MJ, Borgdorff MW, Williams BG, Nagelkerke NJ. Natural history of tuberculosis: duration and fatality of untreated pulmonary tuberculosis in HIV negative patients: a systematic review. PLoS One. 2011;6(4):e17601. Published 2011 Apr 4.
https://doi.org/10.1371/journal.pone.0017601 .

The CFR is estimated at 3.5% in people with no HIV infection on TB treatment [2] Citation 2. Straetemans M, Glaziou P, Bierrenbach AL, Sismanidis C, van der Werf MJ (2011). Assessing Tuberculosis Case Fatality Ratio: A Meta-Analysis. PLoS ONE 6(6): e20755.
https://doi.org/10.1371/journal.pone.0020755 .

The CFR in people with HIV infection on TB treatment is higher than in people with no HIV infection [3] Citation 3. World Health Organization. Global Tuberculosis Report 2021. Geneva: World Health Organization; 2021.
https://apps.who.int/iris/rest/bitstreams/1379788/retrieve .

Risk factors for poor outcomes of TB treatment (death and relapse) include resistance to TB drugs, comorbidities (e.g. untreated HIV infection, diabetes [4] Citation 4. Huangfu P, Ugarte-Gil C, Golub J, Pearson F, Critchley J. The effects of diabetes on tuberculosis treatment outcomes: an updated systematic review and meta-analysis. Int J Tuberc Lung Dis. 2019 Jul 1;23(7):783.
https://doi.org/10.5588/ijtld.18.0433 ), and cavities and high bacillary load [5] Citation 5. Imperial, M.Z., Nahid, P., Phillips, P.P.J. et al. A patient-level pooled analysis of treatment-shortening regimens for drug-susceptible pulmonary tuberculosis. Nat Med 24, 1708–1715 (2018).
https://doi.org/10.1038/s41591-018-0224-2 .