Changing Incidence and Risk Factors for Kaposi Sarcoma by Time Since
Starting Antiretroviral Therapy: Collaborative Analysis of 21 European
Cohort Studies
Background. Kaposi sarcoma (KS) remains a frequent cancer in human
immunodeficiency virus (HIV)-positive patients starting combination
antiretroviral therapy (cART). We examined incidence rates and risk
factors for developing KS in different periods after starting cART in
patients from European observational HIV cohorts.
Methods. We included HIV-positive adults starting cART after 1 January
1996. We analyzed incidence rates and risk factors for developing KS up
to 90 and 180 days and 1, 2, 5, and 8 years after cART start and fitted
univariable and ultivariable Cox regression models.
Results. We included 109 461 patients from 21 prospective clinical
cohorts in Europe with 916 incident KS cases. The incidence rate per 100
000 person-years was highest 6 months after starting cART, at 953 (95%
confidence interval, 866-1048), declining to 82 (68-100) after 5-8
years. In multivariable analyses adjusted for exposure group, origin,
age, type of first-line regimen, and calendar year, low current CD4 cell
counts increased the risk of developing KS throughout all observation
periods after cART initiation. Lack of viral control was not associated
with the hazard of developing KS in the first year after cART
initiation, but was over time since starting cART increasingly
positively associated (P<.001 for interaction).
Conclusion. In patients initiating cART, both incidence and risk factors
for KS change with time since starting cART. Whereas soon after starting
cART low CD4 cell count is the dominant risk factor, detectable HIV-1
RNA viral load becomes an increasingly important risk factor in patients
who started cART several years earlier, independently of
immunodeficiency