Elecys 1010

After participants fasted overnight, venous blood samples were taken by trained staff and immediately sent to the accredited Laboratory of Clinical Chemistry, Västmanland County Hospital, Västerås, Sweden. Plasma levels of NT-proBNP were measured by a commercially available sandwich immunoassay using monoclonal antibodies and separation based on biotin-streptavidin binding (Elecys 1010 and Cobas e411, Roche Diagnostics, Germany). The within-run coefficients of variation were 3.1 and 3.6 % for low and high levels of NT-proBNP, respectively. Glomerular filtration rate (eGFR) was estimated from serum creatinine standardized to isotope dilution mass spectrometry using the CKD-EPI equation [19 (link)].

After participants fasted overnight, venous blood samples were taken and immediately sent to the accredited Laboratory of Clinical Chemistry, Västmanland County Hospital, Västerås, Sweden. Plasma levels of NT‐proBNP were measured by a commercially available sandwich immunoassay using monoclonal antibodies and separation based on biotin‐streptavidin binding (Elecys 1010 and Cobas e411; Roche Diagnostics, Mannheim, Germany). The within‐run coefficients of variation were 3·1% and 3·6% for low and high levels of NT‐proBNP, respectively.

Plasma levels of NT-proBNP were determined at baseline by a sandwich immunoassay using monoclonal antibodies and biotin-streptavidin separation (Elecys 1010 and Cobas e411 instruments, Roche Diagnostics, Germany) [21 (link)]. The analytical range was 5–35,000 ng/L and total coefficient of variation (CVa) of 5.4% and 4.4% at 101 ng/L and 908 ng/L, respectively. Serum creatinine was measured by the Jaffé method standardized against isotope dilution mass spectrometry (Synchron LX 20 and UniCel DxC instruments, Beckman Coulter, USA) with a total CV of 5.3% and 2.4% at 90 µkat/L and 379 µkat/L, respectively. Total cholesterol was measured by enzymatic conversion of cholesterolesterase by a time-endpoint method (Synchron LX 20 and UniCel DxC instruments, Beckman Coulter, USA) with a total CV of 1.5% and 1.6% at 3.18 mmol/L and 7.7 mmol/L, respectively. HbA1c was measured using high-performance liquid chromatography using cation exchange separation and calibrated against the Swedish Mono S method (TOSOH automated Glycohemoglobin Analyzer G7, Tosoh, Japan). HbA1c Mono S was converted to IFCC units by the equation $HbA1c\left(I,F,C,C\right)=HbA1c\left(M,o,n,o,S\right)\times 10.45-10.62$ . This formula differs slightly from the IFCC master equation $HbA1c\left(I,F,C,C\right)=HbA1c\left(M,o,n,o,S\right)\times 10.11-8.94$ and is due to a recalculation in 2004 [22 (link), 23 (link)].