Wide-range CRP versus high-sensitivity CRP on Roche analyzers: focus on low-grade inflammation ranges and high-sensitivity cardiac troponin T levels

<p>Wide-range C-reactive protein (wr-CRP) has been proposed as an economical alternative to high-sensitivity C-reactive protein (hs-CRP) for the evaluation of low-grade inflammation-associated cardiovascular risk (LGI-CVR). Concomitant values of serum hs-CRP and plasma wr-CRP ≤5 mg/L, and high-sensitivity cardiac troponin T (hs-cTnT), all assayed on Roche Diagnostics analyzers over a 1.8-year period, were extracted from a hospital laboratory database. Hs-CRP and wr-CRP values were compared (Bland–Altman method; Deming’s correlation), then separately classified into low (<1 mg/L), moderate (1–3 mg/L) and high (>3 mg/L) LGI-CVR ranges for agreement test (κ), assessed before and after Deming’s regression-based adjustment of wr-CRP (Adj-wr-CRP). Wr-CRP and hs-CRP values were strongly correlated, with linearity, whether below 5 mg/L (<i>n</i> = 744; τ = 0.933; <i>p</i> < .001) or below 1 mg/L (<i>n</i> = 283; τ = 0.823; <i>p</i> < .001). Overall, wr-CRP values were lower than hs-CRP (mean bias: –0.11 ± 0.17 mg/L). Agreement was good, with 8.1% of wr-CRP values misclassified compared to hs-CRP (κ: 0.874), and weakly improved after regression-based adjustment (7.7% reclassified values; κ: 0.881). Lowering the Adj-wr-CRP cutoff of the moderate LGI-CVR subrange from 1.0 to 0.9 mg/L resulted in an almost perfect agreement (3.2% reclassified data; κ: 0.950). Hs-cTnT concentration was positively associated with hs-CRP, wr-CRP, and Adj-wr-CRP (<i>p</i> < .001). Within each LGI-CVR subrange, hs-cTnT medians were similar regardless of the hs-CRP, wr-CRP or Adj-wr-CRP used for risk classification. Based on hs-cTnT, this study supports the use of wr-CRP as a low-cost alternative to hs-CRP for cardiovascular risk evaluation.</p

Hemolysis indexes for biochemical tests and immunoassays on Roche analyzers: Determination of allowable interference limits according to different calculation methods

<div><p></p><p><b><i>Objectives.</i></b> To determine the hemolysis interference on biochemical tests and immunoassays performed on Roche Diagnostics analyzers, according to different maximum allowable limits. <b><i>Design and methods.</i></b> Heparinized plasma and serum pools, free of interferences, were overloaded by increasing amounts of a hemoglobin-titrated hemolysate. This interference was evaluated for 45 analytes using Modular^® and Cobas^® analyzers. For each parameter, the hemolysis index (HI) corresponding to the traditional ± 10% change of concentrations from baseline (± 10%Δ) was determined, as well as those corresponding to the analytical change limit (ACL), and to the reference change value (RCV). Then, the relative frequencies distribution (% RFD) of hemolyzed tests performed in a hospital laboratory over a 25-day period were established for each HI as allowable limit. <b><i>Results.</i></b> Considering the ± 10%Δ, the analyte concentrations enhanced by hemolysis were: Lactate dehydrogenase (LDH), aspartate aminotransferase (AST), folate, potassium, creatine kinase, phosphorus, iron, alanine aminotransferase, lipase, magnesium and triglycerides, decreasingly. The analyte concentrations decreased by hemolysis were: Haptoglobin, high-sensitive troponin T and alkaline phosphatase. Over the 25-day period, the % RFD of tests impacted more than 10%Δ by hemolysis were < 7% for LDH; < 5% for AST, folates and iron; and < 1% for the other analytes. Considering the ACL, HI were lower, giving % RFD substantially increased for many analytes, whereas only four analytes remain sensitive to hemolysis when considering RCV. <b><i>Conclusion.</i></b> This study proposes new HI based on different allowable limits, and can therefore serve as a starting point for future harmonization of hemolysis interference evaluation needed in routine laboratory practice.</p></div