Kaposi Sarcoma Incidence and Survival Among HIV-Infected Homosexual Men After HIV Seroconversion

BACKGROUND Despite the success of combination antiretroviral therapy (cART) in reducing the incidence of Kaposi sarcoma, HIV-infected individuals who have responded to treatment continue to be diagnosed with Kaposi sarcoma. We examine factors associated with the incidence of Kaposi sarcoma among cART-treated HIV-infected homosexual men and changes in their survival after its diagnosis over calendar time. METHODS Data were from HIV-infected homosexual men with well-estimated dates of HIV seroconversion (ie, change in status from being HIV negative to having HIV antibodies detected). Incidence of Kaposi sarcoma was calculated. We used Kaplan-Meier methods to determine survival after Kaposi sarcoma diagnosis in three calendar periods: before 1996, 1996-2000, and 2001-2006. Poisson models were used to examine the effect of risk factors such as current and nadir CD4 cell count (ie, the lowest CD4 cell count ever recorded for a person), duration of infection, and age at diagnosis for Kaposi sarcoma incidence in cART-treated men. All statistical tests were two-sided. RESULTS Among the 9473 men, 555 were diagnosed with Kaposi sarcoma in the period 1986-2006, of whom 319 died. The percentage surviving 24 months after Kaposi sarcoma diagnosis rose statistically significantly during the study period from 35% (95% confidence interval [CI] = 29% to 42%) before 1996 to 84% (95% CI = 76% to 90%) in 1996-2000 and to 81% (95% CI = 70% to 88%) in 2001-2006 (P < .001). Seventy men were diagnosed with Kaposi sarcoma after starting cART. Current (ie, within 6 months) CD4 cell count was associated with incidence of Kaposi sarcoma among cART-treated men (rate ratios [RRs] = 18.91, 95% CI = 8.50 to 42.09, for CD4 level category <200 cells per cubic millimeter; RR = 3.55, 95% CI = 1.40 to 9.00, for 200-349 cells per cubic millimeter; and RR = 4.11, 95% CI = 1.74 to 9.70, for 350-499 cells per cubic millimeter; all compared with > or = 500 cells per cubic millimeter). After adjustment for current CD4 cell count, HIV infection duration, age, or nadir CD4 cell count was not associated with Kaposi sarcoma incidence. CONCLUSIONS Among cART-treated HIV-infected homosexual men, current CD4 cell count was the factor most strongly associated with the incidence of Kaposi sarcoma. Survival estimates after Kaposi sarcoma diagnosis have improved over time.