Background: The outcome of Kaposi sarcoma (KS) varies. While many patients do well on HAART, others have a progressive disease and need chemotherapy, which often produces only short remissions. In order to predict which patients are at risk of unfavorable evolution and to be able to treat them more aggressively from the start, we established a prognostic score.

Method: Survival analysis (Kaplan Meier and Cox proportional hazards models) of 144 patients prospectively included in the Swiss HIV cohort Study, from January 1996 to December 2004, with KS.

Outcome analyzed: use of chemotherapy and/or death.

Variables analyzed: demographic and immunovirological data on HIV, tumor staging (T0/T1,see J Clin Oncol 1997;15:3085), HHV8 viremia and serological titers to latent and lytic antigens at KS diagnosis.

Results: Of 144 patients, 54 needed chemotherapy or died. In the univariate analysis, tumour stage T1, CD4< 200, positive HHV8 viremia and absence of antibodies against the HHV8 lytic antigene at the time of diagnosis were all significantly associated with a bad outcome.

Using multivariate analysis, the following variables were found to be associated with an increased risk of unfavorable outcome: T1 (HR 5.22; 95%CI 2,97-9,18), CD4< 200 (HR 2.33; 95%CI 1,22-4,45) and positive HHV8 viremia (HR 2,14; 95%CI 1,18-3,89).

They were included in a score ranging from 0 to 4:  T1 stage counted for 2 points, CD4 < 200 for one, and positive HHV8 viremia for one point. Each  point increase was associated with a HR of 2,26 (95%CI 1,79-2,85, see figure).

Conclusion: In multivariate analysis, staging (T1), Cd4 (<200) and positive HHV8 viremia at the time of diagnosis predict evolution towards death or the need of chemotherapy.