The present study included 12
638 PWHA who were KS-free at enrolment and among whom 597 incident KS cases were identified (8.2 per 1000
py; 95% CI, 7.6–8.9). Fifteen per cent of PWHA had AIDS at enrolment and an additional 3119 (24.7%) developed it during follow-up. Among the latter, KS was the AIDS-defining illness in 268, whereas 329 KS cases developed in PWHA who had already manifested another AIDS-defining illness.
shows KS temporal trends: overall KS incidence was 33.3 per 1000
py in 1984–1986 and did not change significantly in the subsequent periods until 1996–1998, when it fell to 5.1 (95% CI, 3.9–6.5) per 1000
py. Kaposi sarcoma incidence further decreased to 1.4 per 1000
py in 1999–2001 and remained constant thereafter. Temporal trends in KS incidence were chiefly driven by men having sex with men (MSM), but they were consistent among other HIV transmission categories ().
Figure 1 Incidence rates of KS by calendar period, overall and according to HIV transmission category. Rates were standardised (direct method) on age and gender, based on Swiss HIV Cohort Study participants. Vertical bars represent 95% CI. MSM: men having (more ...)
A large proportion (48.4%) of available py derived from HAART users and shows the incidence and HR of KS by various characteristics separately among non-users and users of HAART. Incidence of KS decreased from 15.0 per 1000
py in non-users to 1.3 per 1000
py in users (HR, 0.11; 95% CI, 0.08–0.14). Among non-users of HAART, intravenous drug users (HR, 0.09; 95% CI, 0.06–0.13), and heterosexuals and other HIV transmission categories (HR, 0.27; 95% CI, 0.20–0.36) showed a lower KS incidence than MSM. The HR for KS was increased among PWHA older than 35 years (HR, 1.53; 95% CI, 1.29–1.82) and those born in Africa/Middle East (HR, 1.84; 95% CI, 1.10–3.06). Kaposi sarcoma risks among non-users of HAART steeply increased with decreasing CD4 cell count (HR for <50 vs
, 12.85; 95% CI, 9.59–17.23). These associations were also present, but were weaker, among HAART users with the exception of the association with place of birth that became stronger (HR for Africa/Middle East vs
Europe among HAART users, 6.49; 95% CI, 2.79–15.11). In contrast with non-users, no change in the HR for KS was seen among HAART users with CD4 cell counts in the range of 50–
and the only significant risk increase was found for CD4 cell count less than 50 cellsμ
at enrolment (HR, 3.26; 95% CI, 1.53–6.91). On account of the rarity of KS among HAART users, HRs showed, however, broad CIs ().
Incidence rates and HR of KS overall and by selected characteristics, and use of HAART
Among HAART users, CD4 cell count at treatment initiation below 50 cellsμ
, 5.36; 95% CI, 2.08–13.80) (data not shown) was even more strongly associated with KS risk than CD4 cell count at enrolment. Furthermore, KS risk was greatly increased among PWHA who had stopped using any antiretroviral drugs for at least 3 months (HR, 8.14; 95% CI, 4.01–16.54) (). Additional adjustment for CD4 cell count at HAART initiation did not modify the HR for treatment interruption (HR, 9.45; 95% CI, 4.64–19.25, data not shown).
Skin was reported as the presentation site in the majority of KS cases (74.3%). Temporal trends and associations with HAART use and CD4 cell count (overall and in separate strata by HAART use) did not differ by KS presentation site (data not shown).
shows the HR for KS in different periods after HAART initiation compared with non-users. The HR of KS was already reduced by 76% in the first 5 months of use and declined to 0.06 (95% CI, 0.02–0.17) in the subsequent 6 months of use. The reduction in KS risk persisted unchanged up to 84–119 months after HAART initiation (HR, 0.06; 95% CI, 0.02–0.16) ().
Figure 2 Hazard ratio of Kaposi sarcoma in patients receiving highly active antiretroviral therapy (HAART) following treatment initiation. Adjusted for centre, age, gender, HIV transmission category (men having sex with men, other), and CD4 cell count at enrolment. (more ...)
Finally, the 52 HAART users who developed KS were individually reviewed and classified into the following groups: (1) no antiretroviral drug in the 3 months before KS diagnosis; (2) recent initiation of HAART (<6 months before KS diagnosis); (3) severe immunodeficiency (CD4 cell count <100 cellsμ
at KS onset while on HAART for
6 months); and (4) none of the above (data not shown). Eighteen (34.6%) KS cases had not been taking any antiretroviral drug for 3 months or more, and in 10 instances for 12 months or longer. Recent initiation of HAART was identified in 15 KS cases, among whom five of the nine KS were from Africa/Middle East. Severe immunodeficiency was identified among 10 KS cases. Nine KS cases, all from the MSM transmission category, could not be assigned to any of the three categories above. Five of them (aged 35, 49, 52, 56, and 63 years) had a CD4 cell count
(i.e., 405, 440, 557, 596, 782) at KS diagnosis.