ABSTRACT Apolipoprotein B (ApoB) is a key marker of atherogenic lipoprotein burden, but conventional plasma‐based testing requires venous sampling and centralized laboratory infrastructure. Dried blood spot (DBS) sampling offers a minimally invasive alternative suitable for decentralized settings. This study evaluated the analytical performance of a DBS‐based ApoB assay on the Chem7 semi‐automated analyser and compared it with the Abbott ARCHITECT ci4100 plasma reference method. DBS samples prepared from 50 de‐identified EDTA whole‐blood specimens were extracted in saline and analysed using an immunoturbidimetric ApoB assay on the Chem7 analyser with a correction factor of 2 applied for haematocrit dilution. Paired plasma specimens were analysed on the ARCHITECT ci4100. Method comparison included Passing–Bablok and Deming regression and Bland–Altman analysis. Potential outliers were assessed using Grubbs’ test ( α = 0.05). Precision verification followed CLSI EP15‐A3. Corrected DBS ApoB showed strong correlation with plasma values ( r = 0.97; R 2 = 0.94). Passing–Bablok regression showed a slope of 0.872 and intercept of 14.29 mg/dL, consistent with Deming regression. Bland–Altman analysis demonstrated a mean bias of −1.5 mg/dL with acceptable limits of agreement. Eighty percent of results were within ±10% of plasma values. No statistically significant outliers were identified, and precision estimates (within‐day and between‐day coefficients of variations (CVs) of 4.6% and 9.2%) met CLSI criteria. DBS‐based ApoB measurement on the Chem7 analyser provides reliable, reproducible and clinically acceptable agreement with plasma testing, supporting its applicability in decentralized and resource‐limited settings.
Pitampersad et al. (Fri,) studied this question.