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Validation of a severity-of-illness score in patients with tuberculosis requiring intensive care unit admission

Coenraad Frederik N Koegelenberg, Cecile A Balkema, Ynishia Jooste, Jantjie J Taljaard, Elvis M Irusen

Abstract


Background. There is a paucity of data on the determinants of mortality due to tuberculosis (TB) in the intensive care unit (ICU). Objective. To develop a simple severity-of-illness score for use in patients with TB admitted to an ICU.

Methods. A scoring system was generated by retrospectively identifying the four most significant and clinically unrelated predictors of mortality from an existing prospectively collected dataset (January 2012 - May 2013), and combining these with known predictors of poor outcome.

Results. Of 83 patients admitted with TB, 38 (45.8%) died in the ICU. The four parameters identified from the retrospective analysis were: (i) HIV co-infection with a CD4 cell count <200/μL; (ii) a raised creatinine level: (iii) a chest radiograph showing diffuse parenchymal infiltrates/miliary pattern; and (iv) absence of TB treatment on admission. These were combined with septic shock and a low arterial partial pressure of oxygen/fractional inspired oxygen (P:F) ratio to generate a six-point severity-of-illness score (one point for each parameter). The scores for survivors were significantly lower than those for non-survivors (mean (standard deviation) 2.27 (1.47) v. 3.58 (1.08); p<0.01). A score of ≥2 was associated with significantly higher mortality than a score of <2 (7.1% v. 46.4%; odds ratio (OR) 15.03; 95% confidence interval (CI) 1.86 - 121.32; p<0.01), whereas a score of ≥3 was associated with a significantly higher mortality than a score of <3 (64.6% v. 20.0%; OR 7.29; 95% CI 2.64 - 20.18; p<0.01).

Conclusion. The proposed scoring system identified patients at increased risk of dying from TB in the ICU. Further prospective studies are indicated to validate its use. 


Authors' affiliations

Coenraad Frederik N Koegelenberg, Division of Pulmonology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Academic Hospital, Tygerberg, Cape Town, South Africa

Cecile A Balkema, Division of Pulmonology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Academic Hospital, Tygerberg, Cape Town, South Africa

Ynishia Jooste, Division of Pulmonology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Academic Hospital, Tygerberg, Cape Town, South Africa

Jantjie J Taljaard, Division of Infectious Diseases, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Academic Hospital, Tygerberg, Cape Town, South Africa

Elvis M Irusen, Division of Pulmonology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Academic Hospital, Tygerberg, Cape Town, South Africa

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Keywords

Intensive care unit; Mortality; Tuberculosis

Cite this article

South African Medical Journal 2015;105(5):389-392. DOI:10.7196/SAMJ.9148

Article History

Date submitted: 2014-11-10
Date published: 2015-05-27

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