Vitros 950 analyzer

The National Cholesterol Education Program/Adult Treatment Panel III (NCEP ATP III) [26 (link), 27 (link)] definition was used to classify participants having MetS in the Health ABC cohort at the baseline and 6-year follow-up visit. Three of the five components are required for diagnosis: (1) waist circumference ≥102 cm (men) and ≥88 cm (women), (2) hypertension ≥130 mm Hg systolic or ≥85 mm Hg diastolic or antihypertensive medications, (3) fasting blood glucose ≥100 mg/dl or treatment for impaired fasting glucose, (4) triglycerides ≥150 mg/dl or specific treatment, and (5) HDL-C ≤40 mg/dl in men and ≤50 mg/dl in women. Waist circumference was measured using a flexible measuring tape on bare skin at the level of maximal circumference, midway between the lower ribs and anterior superior iliac spine at the level of the umbilicus by trained technicians. Seated systolic and diastolic blood pressures were measured by a manual mercury sphygmomanometer using a standardized protocol. Fasting plasma glucose levels were measured by an automated glucose oxidase reaction (YSI 2300 glucose analyzer, Yellow Springs Instruments, Yellow Springs, Ohio). Triglyceride and high-density lipoprotein (HDL) cholesterol concentrations were measured by a colorimetric technique (Johnson and Johnson Vitros 950 analyzer, Rochester, New York).

The glomerular filtration rate (eGFR) was estimated with the CKD-EPI creatinine-cystatin formula [19 (link)]. The estimated GFR at the 1999–2000 visit (was used to classify participants as having CKD (≤60 ml/min/1.73m²) or non-CKD (>60 ml/min/1.73m²). Serum creatinine was measured from blood collected after an overnight fast by a colorimetric assay using a Vitros 950 Analyzer (Johnson & Johnson, New Jersey, USA) calibrated to isotope-dilution mass spectrometry–traceable standards [20 (link)]. A particle-enhanced immunonephelometric assay on a BNII nephelometer (Siemens, Munich, Germany) was used to measure cystatin C [20 (link)].

Plasma levels of total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol (mg/dL), triglycerides (mg/dL) (Vitros 950 analyzer; Johnson & Johnson, New Brunswick, NJ, USA), glucose (mg/dL; YSI 2300 Glucose Analyzer; Yellow Springs, OH, USA), and insulin (μU/mL; Pharmacia, Uppsala, Sweden) were determined in fasting (≥8 h) blood samples drawn during baseline clinic visit. Insulin resistance was defined by HOMA-IR, using the following formula: [fasting glucose (nmol/L) × fasting insulin level (µU/mL)/22.5] [18 (link),19 (link)].