ABSTRACT
Objective To evaluate the performance of six homocysteine (Hcy) analysis systems.Methods This is a methodological evaluation study.We analyzed six cycle enzymatic systems,and their correlation and deviation compared with chemiluminescence microparticle immunoassay (CMIA) from Abbott Architect plus i2000 system.Precision,accuracy,anti-interference and analytical measuring range (AMR)were evaluated,according to the CLSI EP5-A2,EP15-A2,EP7-A2,EP6-A,EP9-A2 guidelines.To assess the accuracy,we used the reference material SRM 1955 from National Institute of Standards and Technology (NIST),and EQA samples from CAP and National Center of Clinical Laboratory.Regression analysis was conducted using Passing-Bablok method.Linear regression measurement was performed using Cusum method,with a statistical significance level set at P ＜ 0.05.Correlation analysis was conducted using Pearson coefficient,with P ＜0.05 indicating significant difference.Deviation analysis was performed using Bland-Altman method.Results In the six systems (A1-D2) except A1,the within-run CVs were all ＜ 5％ and the between-run CVs were all ＜ 6.7％ at the Hey concentration range of 10-22 μmol/L.The accuracy validation of NIST SRM 1955 showed that the maximum absolute bias were-3.36,1.43,2.24 μmol/L at low,medium and high levels respectively.Measurement of EQA samples from CAP and National Center of Clinical Laboratory showed that the relative bias were all ＜ TEa (2.5 μmol/L or target value ±20％) in the six systems (A1-D2) except A1.Hb and TBIL interference were significant.The upper limit of AMR for six systems were 47.3,69.76,72.1,73.96,46.23 and 48.98 μmol/L respectively.The measurement results of six systems conelated well with that of CMIA system,with Pearson correlation coefficient (r) ＞ 0.975 (P ＜0.01,n ＞40).Compared with CMIA system,the Bland-Altman results showed that the maximum average absolute deviation was 2.9 μmol/L.Conclusions The cycle enzymatic method used to measure homocysteine has good precision,linear range,and anti-interference ability.But it is noticeable that the results of cycle enzymatic was higher than those of CMIA.Meanwhile,the six systems do not apply to measuring urine samples.
ABSTRACT
Objective:To evaluate the performance of paramagnetic particles chemiluminescence microparticle immunoassay ( CMIA) for detection of serum Vitamin B12 ( VitB12 ).Methods: Analysed CMIA system precision, accuracy, anti-interference, analytical measuring range( AMR) ,clinical reportable range ( CRR) and biological reference interval were evaluated,according to the clinical and laboratory standards institude ( CLSI) EP5-A2,EP15-A2,EP7-A2,EP6-A,C28-A3c guidelines.To assess the accuracy,we used the reference material SRM 1955 from national institute of standards and technology ( NIST ) and external quality assessment ( EQA) samples ( LN5-B and K-C) from CAP.Results:The precisions of within-run and between-run were less than standard of manu-facturer when the concentration of VitB12 was 108.84-874.43 pmol/L.The results of SRM1955 met the allowable range of the target val-ue.The results of EQA samples( K-C and LN5-B) also up to the CAP calibration and validation/linear evaluation error limits stipulated standards,and the results through linear verification when the concentration of VitB12 was 89-1 057 pmol/L.The 95% verification interval contains the specified value also.The relative deviation was less than external quality assessment standard from national center for clinical laboratory ( TEa:target value ±25%).Anti-interference evaluation showed without significant interferenc when TG ≤20 mmol/L,Bil ≤300 μmol/L VitC≤1.5 g/L to the VitB12 detection system ( CMIA).AMR validation showed determines the best fit equation was linear equation polynomial.There was the linear relationship when the concentration of VitB12 was 0-1 107 pmol/L.The upper limit of CRR was 110 700 pmol/L,the maximum dilution was 100 times.Biological reference interval validation showed that the overall level of VitB12 in this study reference individuals conform to the standard of manufacturer statement for the population,the overall level of VitB12 in female little higher than male,but no significant differences.Conclusion:Performance of CMIA for detection of serum VitB12 basically met needs of laboratory,which can provide reliable results of VitB12 for laboratory,provide information for the VitB12 status of population in the laboratory evaluation.