How good are systemic symptoms and blood inflammatory markers at detecting individuals with tuberculosis?

The diagnosis of tuberculosis (TB) may be rejected in the absence of symptoms such as fever, sweats or weight loss.

To determine how frequently these features and blood test evidence of inflammation were absent in individuals with TB.

Prospective cohort study of 175 unselected subjects diagnosed with TB at a UK TB service between 2003 and 2006.

Eight (5%) subjects identified by screening and 24 (14%) without culture confirmation were excluded. Of the remaining 143, fever, sweats or weight loss were absent in respectively 37%, 39% and 38%. All three symptoms were absent in 25%. In 88 subjects with pulmonary disease, all three symptoms were absent in 20% (10% of smear-positive cases). Overall, C-reactive protein was normal in 15%, erythrocyte sedimentation rate in 21% and lactate dehydrogenase in 55%. In a multivariable model, factors associated with absent symptoms included drug-resistant TB (adjusted odds ratio [aOR] 3.58, P = 0.004) and female sex (aOR 3.15, P = 0.004).

In our population, TB, including pulmonary disease, frequently presented without fever, sweats or weight loss and with normal blood inflammatory markers. This information is of as much relevance to policy makers seeking to improve active case detection as to clinicians and the general public.