Comparison of Kaposi Sarcoma Risk in Human Immunodeficiency Virus-Positive Adults Across 5 Continents: A Multiregional Multicohort Study

Abstract

Background: We compared Kaposi sarcoma (KS) risk in adults who started antiretroviral therapy (ART) across the Asia-Pacific, South Africa, Europe, Latin, and North America.

Methods: We included cohort data of human immunodeficiency virus (HIV)-positive adults who started ART after 1995 within the framework of 2 large collaborations of observational HIV cohorts. We present incidence rates and adjusted hazard ratios (aHRs).

Results: We included 208140 patients from 57 countries. Over a period of 1066572 person-years, 2046 KS cases were diagnosed. KS incidence rates per 100000 person-years were 52 in the Asia-Pacific and ranged between 180 and 280 in the other regions. KS risk was 5 times higher in South African women (aHR, 4.56; 95% confidence intervals [CI], 2.73-7.62) than in their European counterparts, and 2 times higher in South African men (2.21; 1.34-3.63). In Europe, Latin, and North America KS risk was 6 times higher in men who have sex with men (aHR, 5.95; 95% CI, 5.09-6.96) than in women. Comparing patients with current CD4 cell counts ≥700 cells/µL with those whose counts were <50 cells/µL, the KS risk was halved in South Africa (aHR, 0.53; 95% CI, .17-1.63) but reduced by ≥95% in other regions.

Conclusions: Despite important ART-related declines in KS incidence, men and women in South Africa and men who have sex with men remain at increased KS risk, likely due to high human herpesvirus 8 coinfection rates. Early ART initiation and maintenance of high CD4 cell counts are essential to further reducing KS incidence worldwide, but additional measures might be needed, especially in Southern Africa.

Keywords: HIV; Kaposi sarcoma; antiretroviral therapy; cohort study.

Figure 1.

Map of countries contributing patient data to the descriptive analyses.

Figure 2.

Kaposi sarcoma (KS) incidence rates by time since antiretroviral therapy (ART) initiation in men and women predicted from the crude model with sex and its interaction with region (A), and predicted from the main adjusted model for men and women with a current CD4 cell count of 350–499 cells/µL who started a nonnucleoside reverse-transcriptase inhibitor–based first-line ART regimen between 2008 and 2014 at age 40 years (B).

Figure 3.

Regional effects of current CD4 cell counts on the risk of Kaposi sarcoma (KS) in adults who started antiretroviral therapy (ART). The blocks and horizontal lines represent hazard ratios and 95% confidence intervals (CIs). Points represent the reference categories. *Adjusted for sex and its interaction with region, age and its interaction with region, calendar year of ART start, and first-line ART regimen. **Derived from likelihood ratio test comparing the main adjusted model with the model without interaction of a specific variable with region.