Risk of all-cause mortality in HIV infected patients is associated with clinical, immunologic predictors and the CCR5 Δ32 deletion

Abstract

Objective: Investigation of the interplay between the CCR5 Δ32/wt genotype and demographic, epidemiological, clinical and immunological factors associated with mortality in the cART era.

Design: Longitudinal data from 507 HIV-infected patients following the Δ32 allele detection were analyzed.

Methods: Cumulative 15 years mortality was calculated using Kaplan-Meyer methodology. Hazard ratios were estimated using univariate Cox models. Basing on Akakie information criteria and statistical significance multivariate Cox model was constructed and effect plots presenting adjusted hazard ratio time-dependency were drawn. Analysis of the association of all-cause mortality and CCR5 Δ32/wt genotype prior to the antiretroviral treatment (cART) initiation (n = 507) and on the therapy (n = 422) was also performed.

Results: A mortality rate of 2.66 (CI 2.57-3.19) per 100 person-years was observed. Univariate analysis factors modifying the risk of death included the CCR5 genotype, gender, history of cART, AIDS diagnosis and also CD4 lymphocyte nadir, zenith, the latest CD4 count and stable levels >500 cells/µl. For multivariate analysis the following predictors were selected: CCR5 genotype (HR for wt/wt 2.53, CI 1.16-5.53, p = 0.02), gender (HR for males 1.91, 95%CI 1.1-3.36, p = 0.023), introduction of combined antiretroviral treatment (HR 4.85, CI 3.0-7.89, if untreated or treated <1 month, p<0.0001) CD4 count of 500 cells/µl for six months or more (HR 4.16, CI 1.95-8.88 if not achieved, p = 0.028), the latest CD4 count (HR 5.44, CI 3.39-8.74 for <100 cells/µl, p<0.0001) and history of AIDS (HR 1.69, CI 1.03-2.79, p = 0.039). Among untreated individuals the Δ32/wt genotype was associated with notably better survival (p = 0.026), while among cART treated individuals the Δ32 mutation did not correlate significantly with higher survival rates (p = 0.23).

Conclusions: The Δ32 CCR5 allele is associated with a reduction of the risk of all-cause mortality in HIV (+) patients alongside clinical and immunologic predictors such as AIDS, history of cART, lymphocyte CD4 cell count and gender.

Figure 1. Causes of AIDS-related deaths and CCR5 wt/wt vs. CCR5 Δ32/wt genotype.

¹ AIDS-related malignancy: B-cell lymphoma (n = 4), Burkitt lymphoma (n = 1), immunoblastic lymphoma (n = 1), primary CNS lymphoma (n = 4), non-Hodgkin lymphoma - unspecified location (n = 2); ² Fungal infection: pulmonary candidosis (n = 2), generalised cryptococcosis (n = 1); ³ Tuberculosis: pulmonary (n = 4), tuberculotic sepsis (n = 3).

Figure 2. Causes of non AIDS-related deaths and CCR5 wt/wt vs. CCR5 Δ32/wt genotype.

¹ Hepatic: liver cirrhosis (n = 5), liver insufficiency (n = 3); ² CVD: stroke (n = 1), coronary artery disease (n = 2), pulmonary embolism (n = 1); ³ Non AIDS-related malignancy: Hodgkin lymphoma (n = 1), gastric cancer (n = 1), leukemia (n = 1), testicular cancer (n = 1). Gestosis: death related to pre-eclampsia or eclampsia during pregnancy.

Figure 3. Kaplan-Meyer plots for the most significant parameters.

a – CCR5 genotype, b- gender, c- HIV infection stage at diagnosis, d – antiretroviral treatment history, e- AIDS diagnosis, f – baseline CD4 count of >50 cells/µl, g – nadir CD4 cells >50 cells/µl, h – zenith CD4 >500 cells/µl, i – the most recent CD4 count >500 cells/µl, j- the most recent CD4 count >500 cells/µl, k- CD4 count >500 cells/µl maintained for at least half a year, l - CD4 count >500 cells/µl maintained for at least one year.

Figure 4. Multivariate Cox regression model of factors modifying 15 year mortality among HIV infected patients (favorable versus unfavorable parameter).

Dots represent adjusted hazard ratio (HR) for the unfavorable parameters, lines represent confidence intervals for the HR.

Figure 5. Hazard ratio changes during observation period.

For calculation multivariate Cox regression adjusted for the six selected factors was used. Upper and lower confidence intervals are indicated as the external limits in the plot. For the values of borderline significance (p = 0.1–0.50) the field is marked in green while values of statistical significance (P<0.05) are marked in blue. a-CCR5 genotype, b- gender, c-antiretroviral treatment history, d- CD4 count >500 cells/µl maintained for at least half a year, e-the most recent CD4 count of 100 cells/µl, f- AIDS diagnosis.

Figure 6. Kaplan-Meyer plots presenting the CCR5 Δ32/wt genotype based survival prior to cART introduction (a) and on antiretroviral therapy (b).