Greenaway et al listed predictors for a delay in diagnosis or therapy of active tuberculosis. The authors are from McGill University, University of Alberta, University of Toronto and University of British Columbia.

Predictors of a delay in diagnosis:

(1) age >= 65 years

(2) born in a country with a low incidence of tuberculosis

(3) absence of cough

(4) HIV-positive

(5) respiratory tract smear negative for acid-fast bacilli

(6) concomittant extrapulmonary disease



• Extrapulmonary disease is not precisely defined but appears to refer to extrapulmonary tuberculosis.

• The presence of cavitary lung disease usually prompts the diagnosis.


Indicators of tuberculosis care tended to be worse in hospitals with low or intermediate rates of admissions for tuberculosis (less than 10 in 10,000 admissions).


Many of these factors correlate with a low pre-test probability of tuberculosis.

To read more or access our algorithms and calculators, please log in or register.