Predictive markers of survival in HIV-seropositive and HIV-seronegative Tanzanian patients with extrapulmonary tuberculosis

Setting: Prediction of survival in Tanzanian patients with extrapulmonary tuberculosis (TB). Objective: To evaluate the prognostic value of clinical and laboratory parameters on survival in human immunodeficiency virus (HIV) seropositive and HIV seronegative patients with extrapulmonary TB. Design: Over an 8-month period 192 consecutive patients with extrapulmonary TB, admitted to a major referral centre in Tanzania, were enrolled in the study. Their symptoms, signs and PPD skin test results were noted. Their sera were tested for HIV and analyzed for beta-2-microglobulin content. Univariate risk factors for 12 months' survival after the start of anti-TB chemotherapy were entered into a stepwise Cox regression model. Survival probabilities were estimated according to the number of risk factors. Result: Of the 192 patients 126 (65.6%) were HIV-infected, and 29.7% had disseminated TB. Thirty-five patients, of whom 24 (68.6%) were HIV-positive, withdrew from the study immediately after hospital discharge. For survival analysis 157 patients remained. Within 12 months' follow-up after initiation of anti-TB therapy, the case fatality rate of the 102 HIV-infected patients was 22% and of the 55 HIV seronegative patients 2% (P < 0.001). In the HIV seropositive patients the following independent risk factors were significantly associated with a decreased probability of survival: peripheral lymphadenopathy (Hazard Rate Ratio (HRR) 5.2, 95% Confidence Interval [CI] 1.7-16.2), a decreased activity score (bedridden > 50%/day) (HRR 4.5, 95% CI 1.7-11.7), lymphopenia of < 1000/mu L (HRR 4,4, 95% CI 1.7-11.8), and mycobacteraemia (HRR 4.0, 95% CI 1.2-13.1). An anergic PPD skin test reaction proved to be another independent risk factor when the analysis was performed on 89 patients with available Mantoux test results. In the HIV seropositive patients, the 12 months' survival probabilities were 93%, 86%, 54% and 0% for presence of 0, 1, 2 and > 2 risk factors respectively. Conclusion: Estimation of survival probalilities in patients,vith extrapulmonary TB may be possible without performing CD4 cell counts.