Performance evaluation of five lipoprotein(a) immunoassays on the Roche cobas c501 chemistry analyzer

Measurement of lipoprotein(a) [Lp(a)] is used in risk assessment of atherosclerotic cardiovascular disease (ASCVD). The aim of the current study was to evaluate performance characteristic of five different Lp(a) assays using the cobas c501 (Roche Diagnostics) analyzer.

Lp(a) was measured using five Lp(a) assays (Diazyme, Kamiya, MedTest, Randox, and Roche) configured to mg/dL units. Assays from Diazyme and Kamiya were also configured using nmol/L units in separate experiments. Studies included sensitivity, imprecision, linearity, method comparison, and evaluation of healthy subjects. Imprecision (intra-day, 20 replicates; inter-day, duplicates twice daily for five days) and linearity were evaluated using patient pools. Linearity assessed a minimum of five patient splits spanning the analytical measurement range (AMR). Method comparison used 80 residual serum samples. Specimens from 120 self-reported healthy subjects (61 females / 59 males) were also tested. Method comparison for two assays in nmol/L units was conducted using 96 residual serum samples.

Assay sensitivities met all manufacturer claims. Imprecision studies demonstrated %CVs ranging from 2.5 to 5.2% for the low pool (average concentration from 7.3 to 12.4 ​mg/dL); high pool %CVs ranged from 0.8 to 3.0% (average concentrations from 31.5-50.2 ​mg/dL). Linearity was confirmed for all assays. Variation in accuracy was observed when comparing results to an all method average. Lp(a) results were higher in females versus males in self-reported healthy subjects.

All assays performed according to manufacturer described performance characteristics, although differences were observed across Lp(a) assays tested when compared to an all method average.