Commutability assessment of human urine certified reference materials for albumin and creatinine on multiple clinical analyzers using different statistical models.

Urine albumin concentration and albumin-creatinine ratio are important for the screening of early-stage kidney damage. Commutable urine certified reference materials (CRMs) for albumin and creatinine are necessary for standardization of urine albumin and accurate measurement of albumin-urine ratio. Two urine CRMs for albumin and creatinine with certified values determined using higher-order reference measurement procedures were evaluated for their commutability on five brands/models of clinical analyzers where different reagent kits were used, including Roche Cobas c702, Roche Cobas c311, Siemens Atellica CH, Beckman Coulter AU5800, and Abbott Architect c16000. The commutability study was conducted by measuring at least 26 authentic patient urine samples and the human urine CRMs using both reference measurement procedures and the routine methods. Both the linear regression model suggested by the Clinical and Laboratory Standard Institute (CLSI) guidelines and log-transformed model recommended by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Commutability Working Group were used to evaluate the commutability of the human urine CRMs. The commutability of the human urine CRMs was found to be generally satisfactory on all five clinical analyzers for both albumin and creatinine, suggesting that they are suitable to be used routinely by clinical laboratories as quality control or for method validation of urine albumin and creatinine measurements.

Comparing monovalent and combination hepatitis B vaccine outcomes in children delivered by mothers with chronic hepatitis B.

AIM: We compared the vaccine effectiveness of monovalent and combination hepatitis B vaccine regimens in infants born to chronic hepatitis B carrier mothers. METHODS: An observational cohort of neonates was recruited over 78 months from two public hospital maternity units in Singapore. We enrolled term infants, born to chronic hepatitis B surface antigen-positive mothers regardless of their hepatitis Be antigen status, who completed the hepatitis B virus (HBV) vaccination programme in Singapore. Infants born to mothers on antiviral therapy, or with concurrent hepatitis C or human immunodeficiency virus infection were excluded. All infants received hepatitis B immunoglobulin at birth. One group received three doses of monovalent hepatitis B vaccine (0, 1, 6 months) (regimen A). The other group received two doses of monovalent vaccine, followed by one dose combination vaccine DTaP-IPV-Hib-HBV (0, 1, 6 months) (regimen B). Vaccine effectiveness was determined by immunoprophylaxis failure leading to HBV vertical transmission. Immunogenicity was assessed by hepatitis B surface antibody (anti-HBs) levels at 9 months of age. RESULTS: Total of 177 term neonates received regimen A and 115 received regimen B. Immunoprophylaxis failure rate was low, 2.3 and 2.6% (P = 1.00) in regimen A and B, respectively. Mean anti-HBs titres were similar at 643 ± 374 and 561 ± 396 IU/L (P = 0.08) for regimen A and B, respectively. CONCLUSION: Hepatitis B vaccine regimens using monovalent or combination vaccine for the third dose showed similarly high vaccine effectiveness and low immunoprophylaxis failure rate in term infants born to chronic hepatitis B carrier mothers.

Water Conservation Overrides Osmotic Diuresis During SGLT2 Inhibition in Patients With Heart Failure.

BACKGROUND: Sodium-glucose cotransporter 2 inhibitors are believed to improve cardiac outcomes due to their osmotic diuretic potential. OBJECTIVES: The goal of this study was to test the hypothesis that vasopressin-driven urine concentration overrides the osmotic diuretic effect of glucosuria induced by dapagliflozin treatment. METHODS: DAPA-Shuttle1 (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment) was a single-center, double-blind, randomized, placebo-controlled trial, in which patients with chronic heart failure NYHA functional classes I/II and reduced ejection fraction were randomly assigned to receive dapagliflozin 10 mg daily or placebo (1:1) for 4 weeks. The primary endpoint was change from baseline in urine osmolyte concentration. Secondary endpoints included changes in copeptin levels and solute free water clearance. RESULTS: Thirty-three randomized, sodium-glucose cotransporter 2 inhibitor-naïve participants completed the study, 29 of whom (placebo: n = 14; dapagliflozin: n = 15) provided accurate 24-hour urine collections (mean age 59 ± 14 years; left ventricular ejection fraction 31% ± 9%). Dapagliflozin treatment led to an isolated increase in urine glucose excretion by 3.3 mmol/kg/d (95% CI: 2.51-4.04; P < 0.0001) within 48 hours (early) which persisted after 4 weeks (late; 2.7 mmol/kg/d [95% CI: 1.98-3.51]; P < 0.0001). Dapagliflozin treatment increased serum copeptin early (5.5 pmol/L [95% CI: 0.45-10.5]; P < 0.05) and late (7.8 pmol/L [95% CI: 2.77-12.81]; P < 0.01), leading to proportional reductions in free water clearance (early: -9.1 mL/kg/d [95% CI: -14 to -4.12; P < 0.001]; late: -11.0 mL/kg/d [95% CI: -15.94 to -6.07; P < 0.0001]) and elevated urine concentrations (late: 134 mmol/L [95% CI: 39.28-229.12]; P < 0.01). Therefore, urine volume did not significantly increase with dapagliflozin (mean difference early: 2.8 mL/kg/d [95% CI: -1.97 to 7.48; P = 0.25]; mean difference late: 0.9 mL/kg/d [95% CI: -3.83 to 5.62]; P = 0.70). CONCLUSIONS: Physiological-adaptive water conservation eliminated the expected osmotic diuretic potential of dapagliflozin and thereby prevented a glucose-driven increase in urine volume of approximately 10 mL/kg/d · 75 kg = 750 mL/kg/d. (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment [DAPA-Shuttle1]; NCT04080518).

Vitamin D and its relationship with markers of bone metabolism in healthy Asian women.

BACKGROUND: In this study, we aimed to determine the normal ranges of 25-hydroxy-vitamin D(3) (25-OHD(3)), parathyroid hormone (PTH), and the markers of bone turnover, procollagen type 1 N propeptide (P1NP) and C-terminal cross-linked telopeptide of type 1 collagen (CTX), in normal healthy women in Singapore, and to explore the relationship between vitamin D, PTH, and these markers of bone turnover in the women. METHODS: One hundred and ninety-seven healthy women, aged 25 to 60, were selected from a hospital staff health screening program; 68% were Chinese, 18% Malay, and 14% Indian. P1NP, CTX, and 25-OHD(3) were measured using the Roche Cobas® electrochemiluminescence immunoassay. Serum PTH was measured using the Siemens ADVIA Centaur® immunoassay. RESULTS: Sixty-five percent had 25-OHD(3) concentrations <50 nmol/l. Vitamin D insufficiency (25-OHD(3) < 50 nmol/l) was more prevalent in Malays (89%) and Indians (82%) compared to Chinese (56%). There was no correlation between vitamin D and age. PTH positively correlated with age, and Malays and Indians had higher PTH concentrations than Chinese. There was an inverse correlation between PTH and 25-OHD(3), but no threshold of 25-OHD(3) concentrations at which PTH plateaued. The bone turnover markers P1NP and CTX inversely correlated with age but were not different between ethnic groups. CTX and P1NP exhibited good correlation, however, there was no significant correlation between 25-OHD(3) or PTH concentrations and the bone turnover markers P1NP and CTX. CONCLUSIONS: Healthy women in Singapore have a high prevalence of vitamin D insufficiency. Vitamin D insufficiency was more prevalent in Malays and Indians compared to Chinese.

Practical laboratory considerations amidst the COVID-19 outbreak: early experience from Singapore.

The coronavirus disease 2019 (COVID-19) is a zoonotic viral infection originating from Wuhan, China in December 2019. The World Health Organization has classified this pandemic as a global health emergency due to its virulent nature of transmission, which may lead to acute respiratory distress syndrome. Singapore's health ministry has responded with enhanced surveillance of COVID-19 for all suspected pneumonia cases, further increasing the volume of testing via real-time reverse transcription PCR, as well as samples necessitating stringent infectious control. Collectively, this has implications on the total testing process, laboratory operations and its personnel due to biosafety concerns. Turnaround time for routine testing may also be affected. The aim of this article is to present our tertiary institution's early experience with managing this emerging crisis and offer practical considerations for the preanalytical, analytical and postanalytical phases of laboratory testing in this cohort of patients.

Comparative Clinical Evaluation of the Roche Elecsys and Abbott Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Serology Assays for Coronavirus Disease 2019 (COVID-19).

CONTEXT.­: The use of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serologic tests detects antibodies in the host, contributing to the identification of individuals who have been exposed to coronavirus disease 2019 (COVID-19). OBJECTIVE.­: To critically evaluate 2 commercially available SARS-CoV-2 serology tests. DESIGN.­: A total of 333 unique, nonduplicated serum samples obtained from COVID-19 patients (n = 170) and negative controls (n = 163) obtained before December 2019 were used in the study. Samples were tested on the Roche E411 and Abbott Architect i4000SR platforms, and results were correlated to reverse transcription polymerase chain reaction (PCR) results and clinical symptoms. RESULTS.­: There was a strong level of agreement in the qualitative results between both assays, with a Cohen κ value of .840, P < .001. The specificity for both Roche and Abbott were excellent at 100%. Roche exhibited marginally better performance in the 21 days or more group with a sensitivity of 90.6% (95% CI, 75.8%-96.8%) versus an Abbott sensitivity of 84.4% (95% CI, 68.3%-93.1%), as well as in the 14- to 20-day group with a sensitivity of 85.7% (95% CI, 65.4%-95.0%) versus an Abbott sensitivity of 81.0% (95% CI, 60.0%-92.3%). Less than 14 days of symptoms groups exhibited poor sensitivity at less than 50% for both assays. The areas under curve (± standard error) for Roche (0.894 ± 0.025, P < .001) and Abbott (0.884 ± 0.026, P < .001) were very similar. Potential confounders for negative serologic results include antiretroviral medication use and pauci-symptomatic patients. CONCLUSIONS.­: Specificities for high-throughput Roche and Abbott immunoassays are excellent, but users need to be cautious to interpret serologic test results after 14 days of symptoms to avoid false negatives.

Head-to-head evaluation on diagnostic accuracies of six SARS-CoV-2 serological assays.

In this study, we evaluated and compared six SARS-CoV-2 serology kits including the Abbott SARS-CoV-2 IgG assay, Beckman Access SARS-CoV-2 IgG assay, OCD Vitros OCD Anti-SARS-CoV-2 Total antibody assay, Roche Elecsys Anti SARS-CoV-2 assay, Siemens SARS-CoV-2 Total assay, and cPass surrogate viral neutralising antibody assay. A total of 336 non-duplicated residual serum samples that were obtained from COVID-19 confirmed patients (n=173) on PCR and negative controls (n=163) obtained pre-December 2019 before the COVID-19 pandemic were used for the study. These were concurrently analysed on the different immunoassay platforms and correlated with clinical characteristics. Our results showed all assays had specificity ranging from 99.3% to 100.0%. Overall sensitivity across all days of symptoms, in descending order were OCD (49.1%, 95% CI 41.8-56.5%), cPass (44.8%, 95% CI 37.5-52.3%), Roche (41.6%, 95% CI 34.5-49.0%), Siemens (39.9%, 95% CI 32.9-47.3%), Abbott (39.8%, 95% CI 32.9-47.3%) and Beckman (39.6%, 95% CI 32.5-47.3%). Testing after at least 14 days from symptom onset is required to achieve AUCs greater than 0.80. OCD and cPass performed the best in terms of sensitivity for >21 days symptoms with 93.3% (95% CI, 73.5-99.2%) and 96.7% (95% CI, 82.8-99.9%), respectively. Both also shared the greatest concordance, kappa 0.963 (95% CI 0.885-1.0), p<0.001, and had the lowest false negative rates. Serology results should be interpreted with caution in certain cases. False negatives were observed in a small number of individuals with COVID-19 on immunosuppressive therapy, pauci-symptomatic or who received antiretroviral therapy. In conclusion, all assays exhibited excellent specificity and total antibody assays with spike protein configurations generally outperformed nucleocapsid configurations and IgG assays in terms of diagnostic sensitivity.

The choice of estimating equations for glomerular filtration rate significantly affects the prevalence of chronic kidney disease in a multi-ethnic population during health screening.

BACKGROUND: Patients present to the National University Hospital of Singapore and select one of several health screening packages after counselling. The prevalence of chronic kidney disease (CKD) in this population when different glomerular filtration rate (GFR) estimating equations are used has not been examined. METHODS: Demographic data and urinalyses of patients from 2000 to 2005 were extracted from laboratory computer databases and analysed. CKD was classified into stages according to the US National Kidney Foundation guidelines by eGFR (mL/min per 1.73 m(2)) using the four-variable Modification of Diet in Renal Disease equation. GFR of ethnic Chinese was also estimated using Ma's equation 8 (cGFR). Stage 1 and normal (eGFR or cGFR > 90) was discriminated by urinary microscopy or dipstick for proteinuria, albuminuria, hematuria or leukocyturia. RESULTS: There were 3979 screenings (55.9% males, 61.9% Chinese). Means: age = 47.0 +/- 12.3 years, creatinine = 80.1 +/- 26.5 micromol/L, eGFR = 89.6 +/- 19.7, cGFR = 110.8 +/- 23.8 and (eGFR + cGFR) = 102.5 +/- 24.9. By eGFR in all patients, the prevalence of CKD was 45.7%, 50.6%, 3.3%, 0.3% and 0.08% for stages normal or 1, 2, 3, 4 and 5, respectively. For Chinese patients only, eGFR and cGFR resulted in a different distribution (eGFR%/cGFR%): 24.9/50.5, 15.2/29.3, 56.8/19.7, 3/0.8, 0.2/0.2, 0/0 for stages 'Normal', 1, 2, 3, 4 and 5, respectively (P < 0.001). CONCLUSION: The prevalence of moderate to severe CKD (stage 3 to 5) in patients presenting for health screening in Singapore was 3.7%. Notably, the prevalence of mild to moderate CKD (stages 1, 2 and 3) in Chinese patients was affected significantly by the choice of GFR estimating equation.

Maternal HBeAg positivity and viremia associated with umbilical cord blood hepatitis B viremia.

BACKGROUND: Hepatitis B (HBV) transmission may result from in utero transmission. We aimed to determine the correlation between maternal serum and umbilical cord blood HBV DNA levels in infants delivered by chronic HBV-infected mothers and to describe the effect of cord blood viremia on vertical transmission. METHODS: A prospective cohort of 92 chronic HBV-infected mother-and-child pairs recruited over three years was analyzed. Maternal and cord blood were tested for HBV DNA by real-time PCR. Standard immunoprophylaxis with both active and passive immunization was administered to all infants. Serological testing was performed on all infants at 9 months of age. RESULTS: Moderate positive correlation of the maternal HBV DNA with cord blood HBV DNA was demonstrated (r2 = 0.521, p = <0.001). HBeAg +ve mothers were younger with higher HBV and cord viremia. At 9 months of age, one infant was infected. Infants delivered by HBeAg positive mothers and mothers with high HBV DNA of more than 6 LOG IU/mL (1 x 106 IU/mL) have increased relative risk of cord blood viremia. CONCLUSIONS: Maternal HBV DNA and presence of HBeAg were positively correlated to cord blood HBV DNA in infants delivered by chronic HBV-infected mothers. Our data suggest that reducing maternal viremia during the antenatal period may help to reduce cord blood viremia.

Evaluation of the automated ADVIA centaur® XP syphilis assay for serological testing.

We evaluated the performance of the ADVIA Centaur XP Syphilis assay (Siemens Healthcare Diagnostics, Tarrytown, NY, USA) using samples previously tested on the ARCHITECT i4000SR system (Abbott Diagnostics, Lake Forest, IL, USA) and confirmed by the Treponema pallidum particle agglutination assay (TPPA) (SERODIA-TPPA, Fujirebio Diagnostics Inc., Malvern, PA, USA). Clinical patient information was included to aid resolution of discordant samples where available. Precision, interference, and cross-reactivity were also assessed. Relative to patient clinical status, the sensitivity of both the ADVIA Centaur XP and the ARCHITECT assays was 100% (95% CI, 93.9-100), and the specificity of the ADVIA Centaur XP assay was 95.5% (95% CI, 90.4-98.3), which was slightly higher than that of the ARCHITECT assay at 93.9% (95% CI, 88.4-97.3). Overall agreement relative to patient clinical status was 96.9% (95% CI, 93.3-98.8) for the ADVIA Centaur XP assay and 95.8% (95% CI, 91.9-98.2) for the ARCHITECT assay. Overall agreement between the two automated assays was 96.9% (95% CI, 93.3-98.8). ADVIA Centaur XP assay precision was <5% at all index values tested. No significant interference was observed for lipemia or hemolysis; a small effect was seen with some samples for bilirubin. The assay exhibited no significant cross-reactivity with a number of potential interfering factors. The ADVIA Centaur XP Syphilis assay can be considered a sensitive and accurate assay for identification of treponemal antibodies in screening populations as well as patients presenting with suspicion of syphilitic infection.

Serologic Responses After Hepatitis B Vaccination in Preterm Infants Born to Hepatitis B Surface Antigen-Positive Mothers: Singapore Experience.

BACKGROUND: The Advisory Committee on Immunization Practices (ACIP) recommends a 4-dose vaccination schedule for preterm low birth weight infants (<2 kg) and a 3-dose vaccination schedule for preterm infants (≥2 kg) born to hepatitis B surface antigen (HBsAg)-positive mothers. However, data remain limited for these high-risk infants, and the optimal dosing schedule in Asia is not well established. AIM: The aim of this study was to evaluate the serologic vaccine responses in preterm infants born to HBsAg-positive mothers using current vaccination guidelines. METHODS: Preterm babies of gestation less than 37 completed weeks born to HBsAg-positive mothers were prospectively recruited during 6 years (June 2009 to December 2015) and retrospectively recruited via convenience sampling in 2 years (June 2013 to April 2015) in 2 tertiary pediatric centers. The preterm infants were given 4 or 3 vaccine doses as per ACIP 2005 guidelines. Vaccine response was defined as achieving hepatitis B surface antibody values of >10 IU/L [Abbott Architect (Abbott Laboratories, Chicago, IL)] at 9 months of chronologic age. RESULTS: A total of 24 preterm infants were recruited. Four had a birth weight <2 kg. Of 23 surviving infants, all were negative for HBsAg. One baby (4.5%) did not achieve adequate vaccine response. All 4 infants with birth weight <2 kg achieved seroprotective values. CONCLUSION: The current ACIP-recommended vaccination schedule results in adequate antibody responses in preterm infants of HBsAg-positive mothers.

Limited benefit of hepatitis B immunoglobulin prophylaxis in children of hepatitis B e antigen-negative mothers.

INTRODUCTION: In 2006, Singapore adopted the universal hepatitis B immunoglobulin (HBIg) policy. Since then, all infants of hepatitis B surface antigen (HBsAg)-positive mothers receive HBIg, irrespective of maternal hepatitis B e antigen (HBeAg) status. However, the benefits of HBIg for infants of HBeAg-negative mothers are unclear. We compared the vertical transmission rates among children of HBeAg-negative mothers who were given HBIg versus a retrospective cohort who were not given HBIg, to determine its protective effect. METHODS: This observational study involved pregnant HBsAg-positive women seen at National University Hospital, Singapore, between June 2009 and December 2013. If the infants of these mothers completed the recommended vaccination schedule, they were recruited into the study, along with their older siblings. Serological testing for the children was performed three months after completion of the last dose of vaccine, and hepatitis B virus (HBV) surface gene sequencing was carried out if HBV DNA was detected. RESULTS: A total of 111 infants and 47 siblings were recruited. 2 (1.5%) children were found to have vertical transmission despite receiving HBIg, while no incidences of vertical transmission were found among the historical controls who did not receive HBIg (p = 1.00). CONCLUSION: The overall effectiveness of the hepatitis B vaccination programme for children of HBsAg-positive mothers was high, regardless of HBIg administration. The addition of HBIg did not appear to confer additional benefits, in terms of vertical transmission rate, among infants born to HBeAg-negative mothers.

Varicella seroprevalence in healthcare workers in a tertiary hospital: an audit of cross-sectional data.

BACKGROUND: The seroprevalence of varicella in Southeast Asia is not well described especially in healthcare workers (HCW) in the region. We report the varicella seroprevalence among healthcare workers from a diverse range of countries working in a tertiary care hospital in Singapore. METHODS: We audited the results of annual HCW health screening, which included a varicella assay, from the years 2009 to 2014. During this period, there was a change in hospital policy mandating varicella immunity for all newly employed healthcare workers. The serological data were reviewed with employment records on occupation and nationality. Seroprevalence rates were determined by standard commercial enzyme linked immunosorbent assays for each year of testing. Odds of being immune in 2014 were compared by means of multiple logistic regression. RESULTS: A total of 10,585 samples were obtained from 6668 unique individuals over four separate cross-sections of the hospital workforce. A peak seroprevalence of 92.8 % (95 % CI 92.0-93.5) was recorded in 2014. Younger employees had a lower seroprevalence than their older colleagues. In a consolidated sample of 4875 members of the active workforce in October 2014, we identified that Indian nationals were less likely to be immune than their Singaporean national colleagues, odds ratio (OR) 0.26 (95 % CI 0.17-0.43, p < 0.001), while Chinese nationals were more likely to be immune, OR 4.34 (95 % CI 1.61-12.2, p = 0.004), after controlling for year of screening, gender, age-group and vocation. In 2014, being employed as administrative staff, OR 0.43 (95 % CI 0.29-0.64, p < 0.001) or contract service provider, OR 0.30 (95 % CI 0.19-0.47, p < 0.001), was also associated with a lower odds of being immune than being employed as a nurse. CONCLUSIONS: There remain a small number of healthcare workers who are non-immune to varicella in our tertiary hospital. A new pre-employment policy of mandatory screening and vaccination may have increased rates of immunity but more needs to be done to ensure that all of our employees are immune to varicella to protect our vulnerable patients.

Spot urine estimations are equivalent to 24-hour urine assessments of urine protein excretion for predicting clinical outcomes.

Background. The use of spot urine protein to creatinine ratios in estimating 24 hr urine protein excretion rates for diagnosing and managing chronic kidney disease (CKD) predated the standardization of creatinine assays. The comparative predictive performance of spot urine ratios and 24 hr urine collections (of albumin or protein) for the clinical outcomes of CKD progression, end-stage renal disease (ESRD), and mortality in Asians is unclear. We compared 4 methods of assessing urine protein excretion in a multiethnic population of CKD patients. Methods. Patients with CKD (n = 232) provided 24 hr urine collections followed by spot urine samples the next morning. We created multiple linear regression models to assess the factors associated with GFR decline (median follow-up: 37 months, IQR 26-41) and constructed Cox proportional-hazards models for predicting the combined outcome of ESRD and death. Results. The linear regression models showed that 24 hr urine protein excretion was most predictive of GFR decline but all other methods were similar. For the combined outcomes of ESRD and death, the proportional hazards models had similar predictive performance. Conclusions. We showed that all methods of assessments were comparable for clinical end-points, and any method can be used in clinical practice or research.

Severe acute respiratory syndrome without respiratory symptoms or abnormal chest radiograph findings.

We report a serologically confirmed case of severe acute respiratory syndrome (SARS) in a 27-year-old health care worker. The patient reported no respiratory complaints, and the findings of serial chest radiographs were normal. This case illustrates the wide spectrum of clinical illness caused by infection with SARS coronavirus.