Cumulative exposure to viremia: Methods for the implementation of standardized variables in longitudinal HIV studies.

Measures of viremic exposure over time, including HIV viral copy-years or durable viremic suppression, may be more relevant measures of viral load exposure for comorbid outcomes and mortality than single time point viral load measures. However, there are many subjective decisions that go into creating a cumulative variable such as HIV viral copy-years, including the appropriate anchoring point to begin accumulating exposure, the handling of viral load levels below an assay's lower limit of detection (LLD), the handling of gaps in the viral load trajectory, and when to apply the log10 transformation (before or after the accumulation calculation). Different decisions produce different values for HIV viral copy-years, and such differences could impact inferences in subsequent analyses of relationships with outcomes. In this paper, we develop several HIV viral copy-years variables that are standardized across:•Anchoring point•Handling of viral loads measured below the LLD and missing viral load measures•Application of the log10 transformation. These standardized variables may be consistently used in analyses of longitudinal cohort data. We also define a supplementary dichotomous HIV viral load exposure variable that may be used in tandem, or alternatively to, the HIV viral copy-years variables.

Circulating biomarker correlates of left atrial size and myocardial extracellular volume fraction among persons living with and without HIV.

BACKGROUND: Infection with human immunodeficiency virus (HIV) is associated with higher risk for myocardial disease despite modern combination antiretroviral therapy (cART). Factors contributing to this excess risk, however, remain poorly characterized. We aimed to assess cross-sectional relationships between elevations of left atrial volume index (LAVI) and myocardial extracellular volume (ECV) fraction that have been reported in persons living with HIV and levels of circulating biomarkers of inflammation, fibrosis, and myocyte stretch among persons living with and without HIV (PLWH, PLWOH). METHODS: Participants from three cohorts of PLWH and PLWOH underwent cardiovascular magnetic resonance imaging for measurement of LAVI and ECV. Levels of circulating proteins (IL-6, sCD14, galectin-3, NT-proBNP, GDF-15, TIMP-2, MMP-2, and hsTnI) were measured using immunoassays. Associations were assessed using logistic and linear regression, adjusting for demographics, substance use, and clinical characteristics. RESULTS: Among 381 participants with and without HIV, median age (IQR) was 55.1 (51.2, 58.4) years, 28% were female, 69% were Black, and 46% were current smokers. Sixty-two percent were PLWH (n = 235), of whom 88% were receiving cART and 72% were virally suppressed. PLWH had higher levels of sCD14 (p = < 0.001), GDF-15 (p = < 0.001), and NT-proBNP (p = 0.03) compared to PLWOH, while levels of other biomarkers did not differ by HIV serostatus, including IL-6 (p = 0.84). Among PLWH, higher sCD14, GDF-15, and NT-proBNP were also associated with lower CD4 + cell count, and higher NT-proBNP was associated with detectable HIV viral load. NT-proBNP was associated with elevated LAVI (OR: 1.79 [95% CI: 1.31, 2.44]; p < 0.001) with no evidence of effect measure modification by HIV serostatus. Other associations between HIV-associated biomarkers and LAVI or ECV were small or imprecise. CONCLUSIONS: Our findings suggest that elevated levels of sCD14, GDF-15, and NT-proBNP among PLWH compared to PLWOH observed in the current cART era may only minimally reflect HIV-associated elevations in LAVI and ECV. Future studies of excess risk of myocardial disease among contemporary cohorts of PLWH should investigate mechanisms other than those connoted by the studied biomarkers.