Development and validation of artificial intelligence models to predict urinary tract infections and secondary bloodstream infections in adult patients.

BACKGROUND: Traditional culture methods are time-consuming, making it difficult to utilize the results in the early stage of urinary tract infection (UTI) management, and automated urinalyses alone show insufficient performance for diagnosing UTIs. Several models have been proposed to predict urine culture positivity based on urinalysis. However, most of them have not been externally validated or consisted solely of urinalysis data obtained using one specific commercial analyzer. METHODS: A total of 259,187 patients were enrolled to develop artificial intelligence (AI) models. AI models were developed and validated for the diagnosis of UTI and urinary tract related-bloodstream infection (UT-BSI). The predictive performance of conventional urinalysis and AI algorithms were assessed by the areas under the receiver operating characteristic curve (AUROC). We also visualized feature importance rankings as Shapley additive explanation bar plots. RESULTS: In the two cohorts, the positive rates of urine culture tests were 25.2% and 30.4%, and the proportions of cases classified as UT-BSI were 1.8% and 1.6%. As a result of predicting UTI from the automated urinalysis, the AUROC were 0.745 (0.743-0.746) and 0.740 (0.737-0.743), and most AI algorithms presented excellent discriminant performance (AUROC > 0.9). In the external validation dataset, the XGBoost model achieved the best values in predicting both UTI (AUROC 0.967 [0.966-0.968]) and UT-BSI (AUROC 0.955 [0.951-0.959]). A reduced model using ten parameters was also derived. CONCLUSIONS: We found that AI models can improve the early prediction of urine culture positivity and UT-BSI by combining automated urinalysis with other clinical information. Clinical utilization of the model can reduce the risk of delayed antimicrobial therapy in patients with nonspecific symptoms of UTI and classify patients with UT-BSI who require further treatment and close monitoring.

Muscle mass has a greater impact on serum creatinine levels in older males than in females.

Background and aims: We analyzed the effects of age and sex on the relationship between muscle mass and serum creatinine levels in an apparently healthy population, including older adults. Materials and methods: We retrospectively evaluated 1,502 individuals from the Korea National Health and Nutrition Examination Survey (KNHANES) and 4,586 individuals from the Health Check (HC) groups. We utilized data from the KNHANES and HC groups on serum creatinine levels and skeletal muscle mass index (SMI), determined using dual X-ray absorptiometry or bioelectric impedance analysis. Results: A significant negative correlation between SMI and age was observed in both the KNHANES and HC groups in males but not in females. In males, serum creatinine levels showed a significant negative correlation with age in both the KNHANES (r = -0.522, P < 0.0001) and HC groups (r = -0.451, P < 0.0001). In females, there was no significant correlation between serum creatinine levels and age in the KNHANES (r = -0.016, P = 0.5985) and HC group (r = -0.011, P = 0.5618). Conclusions: Serum creatinine levels decrease more significantly in older males than in older females due to sex-specific muscle mass decline.

Calf Circumference as an Indicator for Cystatin C Testing in Hospitalized Elderly Male Patients for Detecting Hidden Renal Impairment.

Serum creatinine is used to measure the estimated glomerular filtration rate (eGFR); however, it is influenced by muscle mass and may therefore overestimate renal function in patients with sarcopenia. We examined calf circumference (CC) as a convenient muscle mass evaluation tool that can potentially indicate the need to test for cystatin C instead of creatinine in elderly inpatients. We retrospectively reviewed the electronic health record of 271 inpatients aged 65 or over. CC was determined by measuring the thickest part of the nondominant calf. eGFRcys and eGFRcr were calculated using cystatin C and creatinine levels, respectively. We evaluated optimum CC cutoff values using the eGFRcys/eGFRcr ratio for detecting hidden renal impairment (HRI, defined as eGFRcr ≥ 60 mL/min/1.73 m2 but eGFRcys < 60 mL/min/1.73 m2). CC showed a significant positive correlation with the eGFRcys/eGFRcr ratio in both sexes. The areas under the receiver operating characteristic curve were 0.725 and 0.681 for males and females, respectively. CC cutoffs with a sensitivity or specificity of 90% or 95% might be used to detect HRI in males. In conclusion, utilizing the optimum cutoff, CC could be a cost-effective screening tool for detecting HRI in elderly male patients using cystatin C as an add-on test.

A single-center experience on long-term clinical performance of a rapid SARS-CoV-2 Antigen Detection Test, STANDARD Q COVID-19 Ag Test.

The COVID-19 pandemic in Korea has dynamically changed with the occurrence of more easily transmissible variants. A rapid and reliable diagnostic tool for detection of SARS-CoV-2 is needed. While RT-PCR is currently the gold standard for detecting SARS-CoV-2, the procedure is time-consuming and requires expert technicians. The rapid antigen detection test (RADT) was approved as a confirmatory test on 14 March 2022 due to rapid dissemination of the Omicron variant. The benefits of the RADT are speed, simplicity, and point-of-care feasibility. The aim of our study was to evaluate the clinical performance of RADT compared to RT-PCR in a single center over 15 months, fully covering the SARS-CoV-2 'Variants of Concern (VOC).' A total of 14,194 cases was simultaneously tested by RT-PCR and RADT from January 2021 to March 2022 in Gangnam Severance Hospital and were retrospectively reviewed. PowerChek SARS-CoV-2, Influenza A&B Multiplex Real-time PCR Kit, and STANDARD Q COVID-19 Ag Test were used. Positive rates, sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) were estimated for five periods (3 months/period). Receiver operator characteristic curve (ROC) analysis was performed, and Spearman's rank test assessed the correlation between RT-PCR Ct values and semi-quantitative RADT results. The overall positive rate of RT-PCR was 4.64%. The overall sensitivity and specificity were 0.577 [95% confidence interval (CI) 0.539-0.614] and 0.991 [95% CI 0.989-0.993], respectively. ROC analysis resulted in an area under the curve of 0.786 (P < 0.0001, Yuden's index = 0.568). The PCR positive rates were estimated as 0.11%, 0.71%, 4.51%, 2.02%, and 13.72%, and PPV was estimated as 0.045, 0.421, 0.951, 0.720, and 0.798 in Periods 1, 2, 3, 4, and 5, respectively. A significant and moderate negative correlation between PCR Ct values and semi-quantitative RADT results was observed (Spearman's ρ = - 0.646, P < 0.0001). The RADT exhibited good performance in specimens with low Ct values (Ct ≤ 25.00) by RT-PCR. The PPV was significantly higher in Periods 3 and 5, which corresponds to rapid dissemination of the Delta and Omicron variants. The high PPV implies that individuals with a positive RADT result are very likely infected with SARS-CoV-2 and would require prompt quarantine rather than additional RT-PCR testing. The sensitivity of 0.577 indicates that RADT should not replace RT-PCR. Nonetheless, given the high PPV and the ability to track infected persons through rapid results, our findings suggest that RADT could play a significant role in control strategies for further SARS-CoV-2 variants.

Associations of Perioperative Red Blood Cell Transfusion With Outcomes of Kidney Transplantation in Korea Over a 16-Year Period.

BACKGROUND: This study investigated the associations between transfusion of different types of red blood cell (RBC) preparations and kidney allograft outcomes after kidney transplantation (KT) over a 16-year period in Korea using a nationwide population-based cohort. METHODS: We investigated the reported use of RBCs during hospitalization for KT surgery, rejection, and graft failure status using nationwide data from the National Health Information Database (2002-2017). The associations between the type of perioperative RBC product and transplant outcomes were evaluated among four predefined groups: no RBC transfusion, filtered RBCs, washed RBCs, and packed RBCs (pRBCs). RESULTS: A total of 17,754 KT patients was included, among which 8,530 (48.0%) received some type of RBC transfusion. Of the patients who received RBC transfusion, 74.9%, 19.7%, and 5.4% received filtered RBCs, pRBCs, or washed RBCs, respectively. Regardless of the type of RBC products, the proportions of acute rejection and graft failure was significantly greater in patients receiving transfusion (P < 0.001). Cox proportional hazards regression analyses showed that the filtered RBC and pRBC groups were significantly associated with both rejection and graft failure. The washed RBC group also had hazard ratios greater than 1.0 for rejection and graft failure, but the association was not significant. Rejection-free survival of the pRBC group was significantly lower than that of the other groups (P < 0.001, log-rank test), and graft survival for the no RBC transfusion group was significantly greater than in the other groups (P < 0.001, log-rank test). CONCLUSION: Perioperative RBC transfusion was associated with poor graft outcomes. Notably, transfusion of pRBCs significantly increased transplant rejection. Therefore, careful consideration of indications for RBC transfusion and selection of the appropriate type of RBCs is necessary, especially for patients at high risk of rejection or graft failure.

Establishment of muscle mass-based indications for the cystatin C test in renal function evaluation.

Background: We aimed to suggest muscle mass-based criteria for using of the cystatin C test for the accurate estimated glomerular filtration rate (eGFR). Materials and methods: We recruited 138 Korean subjects and evaluated eGFRcr (derived from Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) based on creatinine) was compared to eGFRcys based on cystatin C as the reference value. The skeletal muscle mass index (SMI) by bioelectrical impedance analysis (BIA) was used as representative of muscle mass. Calf circumference (CC) was also evaluated. We defined the patients by eGFRcr as those with values of eGFRcr ≥ 60 mL/min/1.73 m2 but eGFRcys < 60 mL/min/1.73 m2 as the detection of hidden renal impairment (DHRI). Cut-off values were determined based on muscle mass for the cases of DHRI suggesting the criteria of cystatin C test in renal function evaluation. Results: We confirmed significant negative correlation between %difference of eGFRcr from eGFRcys and SMI (r, -0.592 for male, -0.484 for female) or CC (r, -0.646 for male, -0.351 for female). SMI of 7.3 kg/m2 for males and 5.7 kg/m2 for females were suggested to be significant cutoffs for indication of cystatin C test. We also suggested CC would be valuable for cystatin C indication. Conclusion: We suggested the muscle mass-based objective criteria relating to SMI and CC that would indicate the use of cystatin C to evaluate renal function test in sarcopenic cases. Our results highlight the importance of muscle mass-based selection of renal function.

Reactogenicity and Immunogenicity of the ChAdOx1 nCOV-19 Coronavirus Disease 2019 Vaccine in South Korean Healthcare Workers.

PURPOSE: The association between reactogenicity and immunogenicity of the ChAdOx1 nCOV-19 is controversial. We aimed to evaluate this association among South Korean healthcare workers (HCWs). MATERIALS AND METHODS: Participants received two doses of the ChAdOx1vaccine 12 weeks apart. Blood samples were tested for anti-severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) spike protein receptor binding domain antibodies about 2 months after the first and second doses using the Elecsys Anti-SARS-CoV-2 S assay kits. Adverse events were noted using an online self-reporting questionnaire. RESULTS: Among the 232 HCWs, pain (85.78% after the first dose vs. 58.62% after the second dose, p<0.001) was the most prominent local reaction, and myalgia or fatigue (84.05% vs. 53.02%, p<0.001) was the most prominent systemic reaction. The frequency of all adverse events was significantly reduced after the second dose. After the first dose, the anti-SARS-CoV-2 S showed significantly higher titer in the group with swelling, itching, fever, and nausea. Also, the anti-SARS-CoV-2 S titer significantly increased as the grade of fever (p=0.007) and duration of fever (p=0.026) increased; however, there was no significant correlation between immunogenicity and adverse event after the second dose. The group with pain after the first dose showed a greater increase in the anti-SARS-CoV-2 S difference between the second and first doses compared to the group without pain (542.2 U/mL vs. 363.8 U/mL, p=0.037). CONCLUSION: The frequency of adverse events occurring after the first dose of the ChAdOx1 was significantly reduced after the second dose. Interestingly, the elevation of anti-SARS-CoV-2 S titer was significantly increased in the group with pain after the first dose.

Impact of urinary tract infection-causative microorganisms on the progression to bloodstream infection: A propensity score-matched analysis.

OBJECTIVES: We aimed to determine the risk factors for the progression of urinary tract infection (UTI) to bloodstream infection (BSI) and to evaluate the mortality-associated factors in patients with urinary tract-related BSI (UT-BSI). METHODS: A propensity score-matched study was conducted using clinical data from all adult patients with UTIs in two South Korean hospitals. RESULTS: A total of 84,406 patients with UTIs were enrolled. The relative incidence of UTIs caused by Escherichia coli decreased along with an increase in the incidence of Candida species infections during the study period. UTI caused by E. coli, Klebsiella pneumoniae, Staphylococcus aureus, and Candida species had a relatively high rate of progression to BSI. UT-BSI caused by Candida species (adjusted odd ratio 5.67; 95% confidence interval 3.97-8.11; p < 0.001) was significantly associated with high 30-day mortality. CONCLUSIONS: UTI-causative microorganisms were associated with both progression to UT-BSI and 30-day mortality in patients with UT-BSI. Considering the trend of increasing age of patients and more frequent use of indwelling urologic devices, UT-BSIs caused by other microorganisms than E. coli could be a more serious medical burden in the future.

De Novo Cancer Incidence after Kidney Transplantation in South Korea from 2002 to 2017.

Advances in patient care and immunosuppressive drugs have improved graft survival, resulting in an increase in kidney transplantation (KT); however, persistent immunosuppression is thought to cause late occurrence of cancer. This population-based study consisted of a total of 14,842 patients whose data from the years 2002 to 2017 were collected from the National Health Information Database in South Korea. Malignancies occurred in 7.6% of the total KT patients. Prostate and thyroid cancers were the most common in males and females, respectively. From the age-adjusted incidence analysis, Kaposi's sarcoma showed the highest standardized incidence ratio in both male and female patients. According to the linear regression model, cancer incidence in KT recipients under immunosuppressive conditions increased by approximately 0.1% each month. Patients' age over 39 and the use of prednisolone as an initial steroid regimen were associated with increased risk of cancer development after KT. Our regression and proportional hazards models will help clinicians to predict the approximate cancer incidence risk when monitoring KT recipients. Based on the largest available national database, screening or monitoring methods for cancer detection and prevention can be established for KT patients by considering the factors involved in cancer development.

Age-group-specific reference intervals for anti-Müllerian hormone and its diagnostic performance for polycystic ovary syndrome in a Korean population.

BACKGROUND: We established age-group-specific reference intervals for serum anti-Müllerian hormone (AMH) levels in a Korean population and investigated the effectiveness of AMH assay for polycystic ovary syndrome (PCOS) diagnosis. METHODS: We analyzed serum levels of AMH, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) from 1540 Korean women. Subjects were divided into three groups: healthy, benign gynecologic diseases, and PCOS. Age-group-specific reference intervals and AMH diagnostic performance were estimated. RESULTS: The PCOS group had a median AMH level of 7.0 µg/L, which was higher than for the healthy (1.8 µg/L) and the benign gynecologic diseases (2.7 µg/L) groups. The upper 97.5% reference limits for age groups 12-20 years, 21-34 years, and 35-46 years were 13.2 µg/L, 15.8 µg/L, and 6.6 µg/L, respectively. The area under the curve (AUC) values to estimate AMH ability to discriminate PCOS from healthy women for each age group were 0.741, 0.785, and 0.789, respectively. AUCs for LH/FSH were 0.719, 0.672, and 0.590. CONCLUSIONS: The better diagnostic ability of AMH over LH/FSH in women of late childbearing ages indicates that age and other clinical characteristics should be considered when interpreting these test results.

Prediction of urine culture results by automated urinalysis with digital flow morphology analysis.

To investigate the association between the results of urinalysis and those of concurrent urine cultures, and to construct a prediction model for the results of urine culture. A total of 42,713 patients were included in this study. Patients were divided into two independent groups including training and test datasets. A novel prediction algorithm, designated the UTOPIA value, was constructed with the training dataset, based on an association between the results of urinalysis and those of concurrent urine culture. The diagnostic performance of the UTOPIA value was validated with the test dataset. Six variables were selected for the equation of the UTOPIA value: age of higher UTI risk [odds ratio (OR), 2.069125], female (OR, 1.400648), nitrite (per 1 grade; OR, 3.765457), leukocyte esterase (per 1 grade; OR, 1.701586), the number of WBCs (per 1 × 106/L; OR, 1.000121), and the number of bacteria (per 1 × 106/L; OR, 1.004195). The UTOPIA value exhibited an area under the curve value of 0.837 when validated with the independent test dataset. The UTOPIA value displayed good diagnostic performance for predicting urine culture results, which would help to reduce unnecessary culture. Different cutoffs can be used according to the clinical indication.

Outcomes of kidney transplantation over a 16-year period in Korea: An analysis of the National Health Information Database.

BACKGROUND: This study investigated the outcomes of kidney transplantation (KT) over a 16-year period in Korea and identified risk factors for graft failure using a nationwide population-based cohort. METHODS: We investigated the Korean National Health Insurance Service-National Health Information Database. Health insurance claims for patients who underwent KT between 2002 and 2017 were analyzed. RESULTS: The data from 18,331 patients who underwent their first KT were reviewed. The percentage of antithymocyte globulin (ATG) induction continuously increased from 2.0% in 2002 to 23.5% in 2017. Rituximab began to be used in 2008 and had increased to 141 patients (9.6%) in 2013. Acute rejection occurred in 17.3% of all patients in 2002 but decreased to 6.3% in 2017. The rejection-free survival rates were 78.8% at 6 months after KT, 76.1% after 1 year, 67.5% after 5 years, 61.7% after 10 years, and 56.7% after 15 years. The graft survival rates remained over 80% until 12 years after KT, and then rapidly decreased to 50.5% at 16 years after KT. In Cox's multivariate analysis, risk factors for graft failure included being male, more recent KT, KT from deceased donor, use of ATG, basiliximab, or rituximab, tacrolimus use as an initial calcineurin inhibitor, acute rejection history, and cytomegalovirus infection. CONCLUSIONS: ATG and rituximab use has gradually increased in Korea and more recent KT is associated with an increased risk of graft failure. Therefore, meticulous preoperative evaluation and postoperative management are necessary in the case of recent KT with high risk of graft failure.

Perioperative blood usage and therapeutic plasma exchange in kidney transplantation during a 16-year period in South Korea.

BACKGROUND: The frequency of kidney transplantation (KT) is increasing. Blood transfusion plays an important role in the success of KT. Therapeutic plasma exchange (TPE) is also used for desensitisation in ABO-incompatible KT and treatment of antibody-mediated rejection. MATERIALS AND METHODS: We analysed red blood cell (RBC), platelet, and fresh frozen plasma (FFP) usage and the number of TPE procedures performed during the hospitalisation of KT patients from 2002 to 2017 using the Korean National Health Insurance Service-National Health Information Database. RESULTS: A total of 18,331 KT patients were included in this study. The number of transfused RBCs continued to increase from 4,806 units in 2002-2005 to 12,390 units in 2014-2017. However, the average number of RBCs transfused per patient decreased from 2.17 to 1.79 units. Estimated platelet usage increased from 4,259 units in 2002-2005 to 11,519 units in 2014-2017, and the proportion of filtered platelets increased from 72.6% to 83.4% during the same period. There was a huge increase in the total number of FFP units used, from 2,255 units in 2002-2005 to 51,531 units in 2014-2017. The number of TPE procedures performed also increased from 296 to 6,479 during the same period. Patients with acute rejection accounted for 8.8% of all KT patients, and more RBC and FFP were used for these patients and a greater number of TPE procedures were performed compared to those who did not experience rejection. DISCUSSION: Blood usage and TPE have increased steadily with the increasing numbers of KTs. Therefore, continuous efforts are needed to ensure appropriate perioperative blood preparation and usage for KT patients.

Carbohydrate antigen 19-9 elevation without evidence of malignant or pancreatobiliary diseases.

Although carbohydrate antigen 19-9 (CA 19-9) may be elevated in benign diseases, elevated CA 19-9 may cause a fear of cancer and unnecessary follow-up studies. Research on how to approach systematically in this case is very limited. The purpose of this study was to analyze the clinical features and the causes of CA 19-9 elevation without evidence of malignant or pancreatobiliary diseases. We retrospectively reviewed the medical records of patients who had CA 19-9 elevation (≥80 U/mL) and were found to be unrelated to cancer after follow-up. After exclusion, 192 patients were included in this study. The median level of CA 19-9 was 136.5 U/mL. The causes of CA 19-9 elevation were determined in 147 (76.6%) patients, and that was unknown in 45 (23.4%). The estimated causative diseases were hepatic diseases in 63 patients, pulmonary diseases in 32, gynecologic diseases in 38, endocrine diseases in 13, and spleen disease in 1. Of 45 patients with unknown cause, 35 had normalization of CA 19-9 and 10 had persistently elevated CA 19-9. In conclusion, CA 19-9 elevation without malignancies or pancreatobiliary diseases should be systematically evaluated and followed up. We suggest an algorithm to investigate the causes and follow up these patients.

Diagnostic performance of CA 125, HE4, and risk of Ovarian Malignancy Algorithm for ovarian cancer.

OBJECTIVE: We evaluated the diagnostic performance of CA 125, HE4, and ROMA for ovarian cancer in Koreans and set optimal cutoffs. METHOD: Serum levels of HE4 and CA 125 and the ROMA score were determined in 762 patients with benign gynecological disease and 70 with ovarian cancer. Receiver operating characteristic curves were constructed to calculate the areas under the curve (AUC). CA 125, HE4, and ROMA exhibiting maximum Youden index were determined, respectively, as the optimal cutoffs, and sensitivity and specificity were evaluated by applying those cutoffs. RESULTS: In benign diseases, CA 125 significantly increased in patients with uterine myoma, adenomyosis, endometrial pathology, or endometriosis, but HE4 only increased in patients with adenomyosis. For the diagnosis of ovarian cancer, the combination of CA 125, HE4, and age showed the highest AUC value of 0.892 in the premenopausal group, and ROMA demonstrated the best diagnostic performance, with an AUC of 0.935 in postmenopausal patients. When the optimal cutoff values for CA 125 and HE4 were applied, the sensitivities of CA 125, HE4, and ROMA in premenopausal women were all the same at 0.714, while the specificities were 0.841, 0.974, and 0.972, respectively. In the postmenopausal group, the sensitivities of these markers were 0.857, 0.804, and 0.929, and the specificities were 0.836, 0.887, and 0.800, respectively. CONCLUSION: Although all markers demonstrated good diagnostic performance, they varied depending on the pathologic types of benign diseases and ovarian cancer. For accurate diagnosis of ovarian cancer, CA 125, HE4, and ROMA should be used complementarily.

Analysis of red blood cell use in elective surgeries over 12 years in Korea.

BACKGROUND: Red blood cell (RBC) transfusion is a lifesaving process for patients with perioperative bleeding, but transfusion can cause adverse events. Effective utilization and management of blood products as a limited resource is essential when considering cost-efficiency and patient safety. STUDY DESIGN AND METHODS: We analyzed the number of RBC units used during the hospitalization of patients who had undergone surgical procedures from 2002 to 2013 using National Health Insurance Service-National Sample Cohort data, which include a total of 487,238 cases for 206 selected operations. RESULTS: RBC units were used in 39,637 (8.1%) cases. A total of 60,815 RBC units were transfused with a mean of 0.13 units per patient overall and a mean of 1.53 units per case receiving RBC transfusion. In addition, 56.7% of the RBC units were transfused for females, and 60.1% of RBC units were transfused into patients aged 60 or older. RBC units were used most often in orthopedic surgeries (33.8%), followed by general surgeries (12.0%) and vascular surgeries (11.8%). The number of operations performed in the cohort increased from 27,690 in 2002 to 49,473 in 2013, and the mean number of RBC units used per operation also increased from 0.08 units in 2002 to 0.15 units in 2013. CONCLUSION: Continuous management for blood preparation and transfusion is needed for efficient utilization of blood. Periodic investigation on the use of blood products through nationwide studies could suggest data applicable to blood product preparation for various elective surgical operations.

Laboratory and Clinical Performance of the ADVIA Centaur Anticyclic Citrullinated Peptide Assay for Rheumatoid Arthritis Diagnosis.

CONTEXT.­: Anticyclic citrullinated peptide antibodies are important serologic markers for the diagnosis of rheumatoid arthritis. Several kinds of test reagents for automated immunoassay systems have been developed and used in recent years. OBJECTIVE.­: To evaluate the analytic and diagnostic performance of the new ADVIA Centaur anticyclic citrullinated peptide assay (Siemens Healthineers, Erlangen, Germany) compared with the Elecsys assay (Roche Diagnostics, Mannheim, Germany). DESIGN.­: A total of 576 serum samples were collected from subjects, including 156 patients (27%) with rheumatoid arthritis. Precision performance and analytical measurement range for the ADVIA assay were evaluated. Diagnostic performance of the 2 assays was compared based on sensitivity, specificity, and area under the receiver operating characteristic curves. RESULTS.­: The ADVIA assay showed a within-laboratory imprecision of 3.4% coefficient of variation for levels of 3.36 and 24.99 U/mL. This assay was demonstrated to be linear from 0.4 to 180.0 U/mL. With default cutoff values, sensitivity and specificity for diagnosing rheumatoid arthritis were 71.2% and 97.9%, respectively, for the ADVIA assay and 73.1% and 96.9%, respectively, for the Elecsys assay. With the best cutoff values from the analyses of the receiver operating characteristic curve, the sensitivity of the 2 assays was the same at 75.6%. However, the specificity of the ADVIA assay was 96.4%, whereas that of the Elecsys assay was 94.3%. The area under the receiver operating characteristic curve value for the ADVIA assay was 0.867, which was not significantly different from that of the Elecsys assay (0.865). CONCLUSIONS.­: The ADVIA Centaur anticyclic citrullinated peptide assay showed good analytic and diagnostic performance in diagnosing rheumatoid arthritis.

Retrospective analysis on the diagnostic performances and signal-to-cut-off ratios of the Elecsys Anti-HCV II assay.

BACKGROUND: Anti-HCV assays are widely used as a screening tool for HCV infection. However, diagnostic performances and effective signal-to-cut-off ratios (S/COs) for predicting true HCV infections would vary according to the assays used. Thus, we evaluated the diagnostic performances of the new Elecsys Anti-HCV assay. METHODS: A total of 41 694 cases tested by the Elecsys Anti-HCV II assay (Roche Diagnostics, Germany) during January 2013 to December 2015 were retrospectively analyzed by comparing with the diagnosis on HCV infections determined by patients' medical records and results of laboratory tests. RESULTS: Excluding 62 cases with unclear history of HCV infection, 430 and 41 202 cases were respectively assorted as "true infection" and "no evidence of infection," and 99.85% of the initial results by the Elecsys assay were concordant with the diagnosis on HCV infection. Sensitivity, specificity, positive and negative predictive values were respectively 99.30%, 99.86%, 88.04%, and 99.99%, where the prevalence of the HCV infection was 1.0%. The area under the receiver operating characteristics curve value of the Elecsys assay was 0.9980 (95% confidence interval [CI]=0.9944 to 1.0017). The S/CO by the Elecsys assay for predictive of a true-positive ≥95% of the time was 19.0 (95% CI=15.0 to 25.1). CONCLUSION: The Elecsys Anti-HCV II assay showed excellent diagnostic performances, particularly in terms of sensitivity, specificity, and NPV. However, the results obtained by this assay with S/CO less than a certain value would need to be retested by HCV RNA PCR or another anti-HCV assay.