Cobas mira chemistry system

Plasma was separated from whole blood anti-coagulated with EDTA by centrifugation at 1500g for 10 minutes and stored at -80°C until further use. Plasma glucose, insulin, a lipid profile (total cholesterol, HDL, LDL), and creatinine were measured using the Cobas Mira Chemistry System (Roche Diagnostic Systems, Inc.). Glucose was measured by the hexokinase assay (Sekisui Diagnostics, Charlottetown, Canada), insulin by the immunoturbidimetric assay (Kamiya Biomedical Company, Seattle, WA), LDL-C, HDL-C and triglycerides were measured by enzyme assays using calibrators from Wako Diagnostics (Richmond, VA). Total cholesterol was measured similarly with calibrators and controls from Thermo Electron. Creatinine was measured by the Jaffe reaction using alkaline picarate obtained from Thermo Electron. hsCRP was measured using the VITROS Chemistry Products at a CLIA certified lab. HbA1c was measured using the Bayer A1c Now kit. Complete blood cell counts were determined with the Abbott Cell Dyne.

Fasting plasma glucose (FPG) was measured by the modified hexokinase enzymatic assay (Cobas Mira Chemistry System; Roche Diagnostic Systems, Montclair, NJ). Hemoglobin A1c (HbA1c) was measured with high-performance liquid chromatography and was standardized to the Diabetes Control and Complications Trial. Total cholesterol (TC) and triglycerides were measured enzymatically. HDL-cholesterol was measured by the direct immunoassay method in NHANES 2001–2002 and 2007–2014, whereas it was measured by the heparin manganese precipitation method in NHANES 1988–1994 and 1999–2000. Although there were changes in laboratories, methods, and instruments used for serum lipid measurements across surveys. Lipid measurements from each NHANES were standardized according to the criteria of the Centers for Disease Control and Prevention and the National Heart, Lung, and Blood Institute Lipid Standardization Program. Non-HDL-cholesterol was calculated as TC minus HDL-cholesterol. For persons with triglycerides ≤ 400 mg/dL, LDL-cholesterol was calculated using the Friedewald equation. Laboratory procedures and quality control methods have been described in the NHANES Laboratory/Medical Technologists Procedures Manual (http://www.cdc.gov/nchs/nhanes/nhanes_questionnaires.htm).

Self-report variables were as the below mentioned: age, gender, ethnicity, smoking status, past medical history diagnosed by a doctor (type 2 DM, skin cancer, other cancer, stroke, CHF, and asthma).
Metabolic variables were obtained from blood samples. The hexokinase enzymatic method was adopted to analyze the plasma glucose according to the Cobas Mira Chemistry System (Roche Diagnostic Systems, Indianapolis, IN, USA). The venipuncture time of the participants was after fasted for 6 hours. Serum TC, serum TG, serum HDL and serum LDL were measured by the Hitachi 704 Analyzer (Roche Diagnostics, Indianapolis, IN, USA). Serum CRP level was measured with latex-enhanced nephelometry (Behring Nephelometer II Analyzer System; Behring Diagnostics Inc., Somerville, NJ, USA). The study utilized the Beckman Synchron LX20 instrument to measure other biochemical profiles, such as serum albumin, serum UA, serum total bilirubin, AST, and ALT. Moreover, MAMC, gamma gap, BMI, SBP, and DBP were listed as continuous variables. The database had past the appraisal of the CDC, and all the profiles were obtained under standardized protocols.