The serum level of soluble urokinase receptor is elevated in tuberculosis patients and predicts mortality during treatment: a community study from Guinea-Bissau

OBJECTIVE: To investigate whether the serum level of soluble urokinase plasminogen activator receptor (suPAR) carries prognostic information in individuals infected with Mycobacterium tuberculosis. DESIGN: suPAR was measured by ELISA in 262 individuals at the time of enrolment into a cohort based on suspicion of active tuberculosis and in 101 individuals after 8 months of follow-up. RESULTS: The suPAR levels were elevated in patients with active TB compared to TB-negative individuals (P < 0.001). suPAR levels were highest in patients positive for TB on direct microscopy (n = 84, median suPAR 3.17 ng/ml, P < 0.001), followed by patients negative on direct microscopy but culture positive (n = 35, median suPAR 2.41 ng/ml, P = 0.005) and by patients diagnosed on clinical grounds (n = 63, median suPAR 2.13 ng/ml, P = 0.06) compared to 64 TB-negative individuals (median suPAR 1.73 ng/ml). During the 8-month treatment period, 23 TB cases died. In a multivariate Cox model controlling for HIV status, age, sex, CD4 count and type of TB diagnosis, the mortality increase per ng suPAR was 1.25 (95%CI 1.12-1.40). After treatment, suPAR levels had decreased to the levels of TB-negative individuals. CONCLUSIONS: suPAR levels are elevated in TB patients and associated with mortality. Furthermore, suPAR may be a potential marker of treatment efficacy.