Symptom screening rules to identify active pulmonary tuberculosis : findings from the Zambian South African Tuberculosis and HIV/ AIDS Reduction (ZAMSTAR) trial prevalence surveys

Claassens, M. M. ; Van Schalkwyk, C. ; Floyd, S. ; Ayles, H. ; Beyers, N. (2017-03-03)

CITATION: Claassens, M. M. et al. 2017. Symptom screening rules to identify active pulmonary tuberculosis : findings from the Zambian South African Tuberculosis and HIV/ AIDS Reduction (ZAMSTAR) trial prevalence surveys. PLoS ONE, 12(3):e0172881, doi:10.1371/journal.pone.0172881.

The original publication is available at http://journals.plos.org/plosone

Article

Background: High tuberculosis (TB) burden countries should consider systematic screening among adults in the general population. We identified symptom screening rules to be used in addition to cough ≥2 weeks, in a context where X-ray screening is not feasible, aiming to increase the sensitivity of screening while achieving a specificity of ≥85%. Methods: We used 2010 Zambia South Africa Tuberculosis and HIV/AIDS Reduction (ZAMSTAR) survey data: a South African (SA) training dataset, a SA testing dataset for internal validation and a Zambian dataset for external validation. Regression analyses investigated relationships between symptoms or combinations of symptoms and active disease. Sensitivity and specificity were calculated for candidate rules. Results: Among all participants, the sensitivity of using only cough ≥2 weeks as a screening rule was less than 25% in both SA and Zambia. The addition of any three of six TB symptoms (cough <2 weeks, night sweats, weight loss, fever, chest pain, shortness of breath), or 2 or more of cough <2 weeks, night sweats, and weight loss, increased the sensitivity to ~38%, while reducing specificity from ~95% to ~85% in SA and ~97% to ~92% in Zambia. Among HIV-negative adults, findings were similar in SA, whereas in Zambia the increase in sensitivity was relatively small (15% to 22%). Conclusion: High TB burden countries should investigate cost-effective strategies for systematic screening: one such strategy could be to use our rule in addition to cough ≥2 weeks.

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