Modified Kigali combined staging predicts risk of mortality in HIV-infected adults in Lusaka, Zambia

Abstract

We assessed the utility of the modified Kigali combined (MKC) staging system for predicting survival in HIV-infected Zambian adults in a prospective, longitudinal, open cohort. From 1995 to 2004, HIV-discordant couples (one HIV-infected partner and one HIV-negative partner) were recruited from couples' voluntary counseling and testing centers in Lusaka, Zambia and followed at 3-month intervals. MKC stage, which incorporates clinical stage with erythrocyte sedimentation rate (ESR), hematocrit, and body mass index (BMI), was determined at enrollment. Kaplan-Meier survival and Cox proportional hazard methods were used to calculate median survival and relative hazards. We enrolled 1479 HIV-discordant couples with a combined 7305 person-years of follow-up. Among HIV-infected participants over the 9-year study period, there were 333 confirmed deaths. The time to 50% mortality was 8.5 years with MKC stage 1 and 2 disease compared to 3.7 years with MKC stage 4 disease at enrollment. Survival rates at 3 years were 85% with MKC stage 1 and 2 disease, 74% with MKC stage 3 disease, and 51% with MKC stage 4 disease. A total of 275 HIV-negative partners seroconverted during follow-up. In comparison, survival rates at 3 years were 94% for HIV-negative participants and 92% for participants who seroconverted during follow-up. In multivariate analysis, MKC stage 4 disease (HR = 3.7, 95% CI = 2.7-5.0) remained a strong predictor of mortality. Incorporating ESR, hematocrit, and BMI with clinical staging is a powerful, low-cost tool to identify HIV-infected adults at high risk for mortality.

FIG. 1.

Algorithm for modified Kigali combined (MKC) staging with number of HIV-infected participants from this cohort in each stage (WHO, Lab, and MKC) at enrollment. To demonstrate the flow of this algorithm, 390 participants were staged as clinical (WHO*) stage 3 at enrollment. Of these 390 participants, 230 participants were laboratory stage A (normal hematocrit and ESR results) and 157 participants were laboratory stage B (abnormal hematocrit or ESR results). The 230 participants with clinical stage 3 and laboratory stage A were classified as MKC stage 2 and the 157 participants with clinical stage 3 and laboratory stage B were classified as MKC stage 3. WHO*: clinical stage based on WHO staging with modifications described in Appendix 1.

FIG. 2.

Survival among HIV-infected Zambian adults stratified by MKC stage (n = 1479).