Unicel dxc 660i synchron access

High sensitivity C-reactive protein (CRP) was used as the biomarker for systemic inflammation [28 ]. Serum samples were obtained from participants as part of the NHANES biospecimen collection protocol. CRP was measured using a Beckman Coulter UniCel DxC 660i Synchron Access chemistry analyzer (DxC 660i; Beckman Coulter, Inc., Fullerton, CA USA) for the 2015–2016 survey cycle and a Roche Cobas 6000 chemistry analyzer (Cobas 6000; Roche Diagnostics, Indianapolis, IN USA) for the 2017–2018 survey cycle following laboratory procedures detailed by NHANES [29 ,30 ]. NHANES has reported that 2017–2018 CRP values were 19.6% lower than values measured in 2015–2016 using the DxC 660i instrument. In order to merge the 2015–2016 and 2017–2018 data for this analysis, the following recommended regression equation was applied to values ≤ 23 mg/L (n = 2510) measured with the DxC 660i instrument: Updated DxC 660i value = (0.8695 × Original DxC 660i value) + 0.2954 [30 ]. The 58 values over 23 mg/L remained unchanged as NHANES did not report a recommended adjustment for those values [30 ]. Serum CRP level was dichotomized into two groups: reference (<8.0 mg/L serum CRP) and elevated (≥8.0 mg/L serum CRP) [28 ,31 ].

The principal variables of this study were albumin (independent variable) and CRP (dependent variable). The albumin concentration was measured using the DcX800 method which was as a bichromatic digital endpoint method. CRP was measured on the Beckman Coulter UniCel DxC 600 Synchron and the Beckman Coulter UniCel DxC 660i Synchron Access chemistry analyzers. In addition, the following covariates were included: age, alanine aminotransferase, blood urea nitrogen, creatinine, Gamma Glutamyl Transferase, body mass index, alkaline phosphatase, aspartate aminotransferase, cholesterol, creatine phosphokinase, globulin, lactate dehydrogenase, triglycerides, uric acid, total bilirubin, race/ethnicity, martial status, smoking, high blood pressure, gender. Details of albumin and CRP measurement process and other covariate acquisition process are available at www.cdc.gov/nchs/nhanes/.