Interassay variability was 1.54–9.03%. All the above biomarker assays were performed at the Laboratory for Clinical Biochemistry Research under the direction of Dr Russell Tracy, Department of Pathology, University of Vermont. F2-isoprostanes were measured in the Eicosanoid Core Laboratory at Vanderbilt University. Briefly, F2-isoprostanes find more were quantified using gas chromatography–mass spectrometry after
Sep-Pak (Waters Corporation, Milford, MA, USA) and thin layer chromatography purification as pentafluorobenzyl ester and trimethylsilyl ether derivatives utilizing stable isotope dilution techniques with [2H4]-15-F2t-IsoP (Cayman Chemical, Ann Arbor, MI, USA) as an internal standard. The precision of this assay is ±4%, the accuracy is ±95% and the interassay variability is <8%. Important demographic, HIV and cardiovascular factors are described for the group overall, by ATV status (currently Trametinib nmr taking ATV vs. not) and by total bilirubin level (≥75th percentile vs. <75th percentile). The median and interquartile range
(IQR) are reported for continuous variables and the frequency and percentage for categorical variables. All demographic, HIV and cardiovascular factors, as well as endpoints, were compared based on ATV status and total bilirubin level using unpaired t-tests or Wilcoxon rank sum tests as distributionally appropriate for continuous variables, and χ2 tests, Fisher’s exact tests or Pearson exact χ2 tests as appropriate for categorical variables. Spearman correlation coefficients were determined between total bilirubin as a continuous variable and endpoints.
All for above statistical tests were two-sided and considered significant with P < 0.05. No corrections for multiple comparisons were made in this exploratory study. Next, in order to explore the relationship between FMD and total bilirubin in this sample, univariable followed by multivariable linear regressions were performed. In the univariable analysis, all demographic, HIV and cardiovascular factors, and inflammation, coagulation and oxidative stress markers as well as ATV status and total bilirubin as a dichotomized variable by ≥75th percentile compared with <75th percentile and a continuous variable were modelled with FMD as the outcome. In the first multivariable modelling approach, those variables with P < 0.25 were included in three separate multivariable models with ATV status or total bilirubin, as a categorical or continuous variable, as the independent variable of interest. In addition, a second multivariable modelling approach including clinically relevant variables regardless of statistical association was undertaken.