Association between selected immune markers and low ankle-brachial index in virologically suppressed HIV-infected patients on antiretroviral therapy in Nigeria

Introduction
People living with human immunodeficiency virus (HIV) on effective antiretroviral treatment (ART) are exposed to an increased risk of cardiovascular disease, often linked to inflammation and immune activation. Ankle-brachial index (ABI) has been widely accepted as screening tool for peripheral arterial disease (PAD) and future cardiovascular events, and is inexpensive and noninvasive compared to carotid intima-media thickness measurements. This study aimed at determining the association between low ankle-brachial index and selected immune markers among virologically suppressed HIV-infected participants on ART in Kwara State, Nigeria.

Material and methods
This analytical cross-sectional study was conducted between July 2018 and December 2018. One hundred and fifty HIV-infected participants and fifty HIV non-infected age matched controls were recruited into the study. Ankle-brachial index was measured, and peripheral arterial disease was defined as ABI of < 0.9. Cryopreserved plasma was used to evaluate interleukin (IL)-6 and sCD14. Student’s t-test and c2 test were used to compare continuous and categorical variables. Associations of CVD and immunologic markers with low ABI were assessed using logistic regression analysis.

Results
The study group had significantly lower mean values for ABI and significantly higher mean values of IL-6 and sCD14 compared to the control group (p < 0.05). The prevalence of low ABI (14.6%) was higher in the study group compared to the control group (2%). IL-6 (OR 0.992, p = 0.087) and sCD14 (OR 0.918, p = 0.058) were not associated with low ABI in the study group.

Conclusions
HIV-infected individuals on suppressive ART demonstrate increased levels of IL-6 and sCD14 compared to not infected controls. The impact of inflammation and immune activation on PAD in treated HIV-infection requires further investigation.