Procalcitonin (PCT) is a useful bacterial infection biomarker with the potential for guiding antibiotic therapy. We evaluated the concordance of three automated PCT immunoassays: Kryptor (BRAHMS GmbH, Hennigsdorf, Germany), Atellica IM 1600 (Siemens Healthcare Diagnostics, Munich, Germany), and Cobas e801 (Roche Diagnostics, Mannheim, Germany). In 119 serum samples with a PCT concentration < 5.00 μg/L, Kryptor (reference assay) was compared with the other two immunoassays by Spearman’s rank correlation, regression analysis, and concordance at two antibiotic stewardship medical decision points: 0.25 and 0.50 μg/L. The Atellica IM 1600 and Cobas e801 results showed high correlations with those of Kryptor, with correlation coefficient (ρ) values of 0.97 and 0.99, respectively. However, negative biases were observed in both immunoassays (slope/y-intercept: 0.75/–0.00 for Atellica IM 1600; 0.88/–0.01 for Cobas e801). Atellica IM 1600 and Cobas e801 demonstrated excellent concordance with Kryptor at both medical decision points, with linearly weighted κ values of 0.90 and 0.92, respectively, despite discrepancies, which were more prominent at the 0.25 μg/L medical decision point. Based on these biases and discrepancies, the alternate use of different PCT immunoassays in repeat examinations is inadvisable. Standardization is required before comparing the results of different PCT immunoassays.

Rapid influenza diagnostic test (RIDT) is widely used for the diagnosis of influenza owing to its simplicity and convenience of use. This study aimed to evaluate the performance of a new RIDT, SD Standard F influenza A/B FIA (SD Biosensor, Inc., Korea) (Standard F) and compare its performance with BD Veritor Flu A+B (Veritor), using the results of real-time reverse transcription PCR (rRT-PCR) analysis as the standard for reference. On comparing the results obtained from both the RIDTs and rRT-PCR qualitatively, it was found that the Veritor and Standard F assays have the sensitivity of 65.6% (21/32) and 71.9% (23/32), respectively, for the detection of influenza A with a specificity of 100.0% (68/68). Additionally, both the assays demonstrated a sensitivity of 66.7% (12/18) and specificity of 100.0% (68/68) for the detection of influenza B. The cutoff index (COI) value of the fluorescence color intensity from the Standard F assay, displayed on the device along with the qualitative results, indicated a negative correlation with the Ct value from rRT-PCR for both influenza A and B (P<0.001). The sensitivity of the new RIDT for the detection of influenza was comparable with that of the Veritor assay and the new RIDT could be used as a substitute for existing RIDTs by providing additional information to predict the approximate viral burden of influenza.

Appropriate reference intervals of serum insulin-like growth factor I (IGF-I) is important for diagnosing and monitoring patients with growth hormone-related diseases. To establish reference intervals, adult individuals (n=1,334, 680 men and 654 women) were divided into six age groups (20–29, 30–39, 40–49, 50–59, 60–69, ≥70). Serum IGF-I was measured by chemiluminescence immunoassay (Liaison). Concordance of patient classification based on reference intervals, manufacturer’s intervals, and standard deviation score (SDS) was evaluated. New reference intervals had higher upper and lower limits than those specified by the manufacturer. The agreement between classification using new reference interval and the manufacturer’s reference interval, and that using new reference interval and SDS was 75.0% (weighted kappa, 0.17), 91.9% (weighted kappa, 0.51) in men and 91.0% (weighted kappa, 0.41), 92.5% (weighted kappa, 0.53) in women, respectively. Reference intervals should be established not only based on age and sex, but also on ethnicity and assay method.

BACKGROUND: Recently, a new automated chemistry analyzer, Atellica CH930 (Siemens, Germany), was introduced. It automatically measures internal quality control (QC) materials according to a pre-determined schedule. For this purpose, the instrument has space for storage of QC materials. We evaluated the analytical performance of chemistry items by using the Atellica system. METHODS: The precision of 29 items was evaluated with three levels of QC materials with two storage methods. We stored the QC materials in the dedicated storage space in the instrument during the precision evaluation period. In addition, we aliquoted and stored the materials in the refrigerator, and then loaded the material in a timely manner. Linearity, carry-over, and agreement with current methods were also evaluated. RESULTS: The within-laboratory coefficient of variation (CV) of most items, except for total CO2 (tCO2), was within 5.0% in both QC storage methods without significant differences in CV between storage methods. The CV of tCO2 was 5.2%, 5.8%, and 5.1% at three different levels when the QC materials were stored in a dedicated space in the instrument. The linearity was acceptable, showing <5% nonlinearity. Although good agreement was observed for most items, some items, such as calcium, total bilirubin, aspartate transaminase, and chloride, showed unequivalent results. CONCLUSIONS: Atellica CH930 showed acceptable precision, linearity, and agreement in routine chemistry items. The automatic QC function using the storage device has no problem with stability or precision. It can reduce the manual process, allowing technicians to focus on reviewing the QC results and reporting reliable results.
Appointments and Schedules ; Aspartate Aminotransferases ; Bilirubin ; Calcium ; Chemistry ; Quality Control

The accuracy-based lipid (ABL) proficiency testing (PT) program was started in 2016 by the Korean External Quality Assessment Service to minimize the matrix effect. We analyzed 3 years of the program. We made or purchased six kinds of commutable frozen sera based on the Clinical and Laboratory Standards Institute 37A guideline and distributed it in two rounds per year from 2016 to 2018. We obtained reference values for levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), total glycerides, and triglycerides in each fresh frozen pool at the reference-measurement laboratories. We evaluated the average percent bias of the participating laboratories based on the National Cholesterol Education Program (NCEP) bias limit. The number of participating laboratories evaluating TC, HDLC, LDLC, total glycerides, and triglycerides increased from 164 to 223, 163 to 223, 158 to 214, 98 to 139, and 61 to 82, respectively. The average percent bias of all participating laboratories for TC, HDLC, LDLC, total glycerides, and triglycerides was +0.14%, −0.54%, +2.9%, −1.08%, and −1.32%, respectively. The average percent bias exceeded the NCEP bias limit only once or twice for TC, HDLC, and total glycerides but frequently for LDLC (eight out of 18 pools). The manufacturer-specific bias estimation report seemed useful for traceability. Although the average percent bias of participating laboratories for TC, HDLC, LDLC, total glycerides, and triglycerides was mostly within the bias limit provided by NCEP, cases of bias limit exceeding the NCEP bias limit occurred occasionally, especially for LDLC during the 3 years of the ABL PT program in Korea, suggesting that ABL PT can be used to keep maintaining traceability.
Bias (Epidemiology) ; Cholesterol ; Education ; Glycerides ; Korea ; Laboratory Proficiency Testing ; Lipoproteins ; Reference Values ; Triglycerides