Data analytics improves the diagnostic accuracy of serum free light chain results for detecting monoclonal gammopathy.

OBJECTIVES: To evaluate the real-world performance and reference intervals of the Binding Site Freelite serum free light chain (SFLC) assay (Thermo Fisher Scientific), a global standard for diagnosis, prognostication, and response assessment for monoclonal gammopathies. METHODS: An informatics-based approach was used to retrospectively evaluate concordance between SFLC and the orthogonal Sebia HYDRASYS immunofixation assay results in a large clinical data set consecutively reported between 2010 and 2020. RESULTS: Among patients with monoclonal-negative results by both SFLC and Sebia HYDRASYS immunofixation assays, 25% (1226/5057) had κ/λ ratios (KLRs) outside the manufacturer-defined and International Myeloma Working Group-cited normal reference interval of 0.26 to 1.65. These results were consistent over the study period and were not affected by sex, age, impaired kidney function, or assay antisera lot variation. Assay drift, in addition to other potential factors, affected the KLR distribution. Using International Statistical Classification of Diseases (ICD) codes, kidney function data, and the central 95% of KLR values generated on the Optilite platform (Thermo Fisher Scientific), we derived a new reference interval of 0.67 to 2.13, reducing the KLR false-positive rate to 8%. However, normal KLR persisted among 16% (14/85) of samples with free λ chains by immunofixation, warranting caution during interpretation. CONCLUSIONS: Our analysis indicated that revision of Freelite SFLC reference intervals improves assay interpretation and should prompt reconsideration of Freelite reference intervals worldwide.

Performance of OC-Auto Micro 80 Fecal Immunochemical Test in an Integrated Academic-Community Health System.

GOALS: We aimed to determine the performance of the OC-Auto Micro 80 fecal immunochemical test (FIT) in an average-risk population receiving care in an integrated, academic-community health system. BACKGROUND: The FIT is the most used colorectal cancer (CRC) screening test worldwide. However, many Food and Drug Administration-cleared FIT products have not been evaluated in clinical settings. STUDY: We performed a retrospective cohort study of patients (50 to 75 y old) in the University of Washington Medicine health care system who were screened for CRC by OC-Auto Micro 80 FIT between March 2016 and September 2021. We used electronic health records to extract patient-level and clinic-level factors, FIT use, colonoscopy, and pathology findings. The primary outcomes were the FIT positivity rate and neoplasms detected at colonoscopy. Secondary outcomes were FIT positivity by sex and safety-net versus non-safety-net clinical settings. RESULTS: We identified 39,984 FITs completed by 26,384 patients; 2411 (6.0%) had a positive FIT result (>100 ng/mL of hemoglobin in buffer), and 1246 (51.7%) completed a follow-up colonoscopy. The FIT positive rate was 7.0% in men and 5.2% in women (P <0.01). Among those who completed a colonoscopy after an abnormal FIT result, the positive predictive value for CRC, advanced adenoma, and advanced neoplasia was 3.0%, 20.9%, and 23.9%, respectively. CONCLUSIONS: In a retrospective analysis of a large heterogeneous population, the OC-Auto Micro 80 FIT for CRC screening demonstrated a positivity rate of 6.0% and a positive predictive value for CRC of 3.0%.

Evaluation of a Multilevel Laboratory Stewardship Intervention Targeted to Cardiac and Thoracic Surgical Services at an Academic Medical Center.

CONTEXT.­: Unnecessary laboratory tests are ordered because of factors such as preselected orders on order sets, clinician habits, and trainee concerns. Excessive use of laboratory testing increases patient discomfort via unnecessary phlebotomy, contributes to iatrogenic anemia, increases risk of bloodstream infections, and increases the cost of care. OBJECTIVE.­: To address these concerns, we implemented a multilevel laboratory stewardship intervention to decrease unnecessary laboratory testing, measured by laboratory tests per day attributed to service, across 2 surgical divisions with high laboratory use. DESIGN.­: The multilevel intervention included 5 components: stakeholder engagement, provider education, computerized provider order entry modification, performance feedback, and culture change supported by leadership. The primary outcome of the study was laboratory tests ordered per patient-day. Secondary outcomes included the number of blood draws per patient-day, total lab-associated costs, length of stay, discharge to a nursing facility, 30-day readmissions, and deaths. A difference-in-differences analytic approach assessed the outcome measures in the intervention period, with other surgical services as controls. RESULTS.­: The primary outcome of laboratory tests per patient-day showed a significant decrease across both thoracic and cardiac surgery services, with between 1.5 and 2 fewer tests ordered per patient-day for both services and an estimated 20 000 fewer tests performed during the intervention period. Blood draws per patient-day were also significantly decreased on the thoracic surgery service but not for cardiac surgery. CONCLUSIONS.­: A multilevel laboratory stewardship intervention targeted to 2 surgical services resulted in a significant decrease in laboratory test use without negatively impacting length of stay, readmissions, or mortality.

Calculating estimated glomerular filtration rate without the race correction factor: Observations at a large academic medical system.

BACKGROUND AND AIMS: Creatinine-based MDRD and CKD-EPI equations include a race correction factor, which results in higher eGFR in Black patients. We evaluated the impact on our patient population upon adoption of the CKD-EPI equation and the removal of the race correction factor from the equation. MATERIALS AND METHODS: Retrospective analysis of blood creatinine results and respective eGFR values calculated by the MDRD or CKD-EPI equation without the race correction factor (CKD-EPINoRace) in a large academic medical system over a 20.5-month period. RESULTS: In our population, when changing from MDRD to CKD-EPINoRace, we observed that 3.5% of all patients were reclassified to categorically have worse kidney function. However, we also observed fewer patients overall with eGFR below 60 mL/min/1.73 m2. Around 60 and 20 mL/min/1.73 m2, 2.96% and 0.16% of all patients > 65 years of age were reclassified, as were 4.29% and 0.03% of all Black patients, respectively. When calculated with CKD-EPINoRace, median eGFR was not meaningfully different between Black and non-Black patients (p = 0.02). CONCLUSIONS: Changing from MDRD to CKD-EPINoRace could lead to a lower referral rate to nephrology. The distributions of creatinine and eGFR calculated with CKD-EPINoRace were not meaningfully different in Black and non-Black patients.

Evaluation of Patient Demographics in Clinical Cancer Genomic Testing.

BACKGROUND: Inequitable use of next-generation sequencing (NGS) testing for cancer risk and treatment can contribute to heath disparity. Consequently, it is important to assess the population receiving this testing. In this article, we characterize the population receiving both germline and somatic NGS testing for cancer predisposition and precision oncology at the Genetics and Solid Tumors Laboratory of the University of Washington Medical Center. METHODS: The general demographics, including ancestry, of patients receiving somatic testing to identify genes related to cancer treatment or prognosis, diagnosis, or germline testing for heritable cancer risk from January 2015 to July 2017 were characterized. Ancestry was determined using single nucleotide variant data and documented pedigree. The demographics of the patient population receiving testing were compared with a reference population comprising patients receiving care from the University of Washington Medical Center with a diagnosis of malignant neoplasm of breast, ovary, colon, rectum, or prostate between January 2015 and May 2018. RESULTS: A total of 2210 unique patients were included in this study. Women composed 66% of our total tested population. Patients of European ancestry composed 78% of the tested cohort. The percentages of American Indian/Alaskan Native and Native Hawaiian/Other Pacific Islander in the cohort receiving NGS testing were significantly different than their respective distributions in the reference cohort. CONCLUSIONS: Characterizing the demographics of patients receiving NGS testing for cancer predisposition and precision oncology using single nucleotide variant data and documented pedigree may help identify potential health disparities.

Measuring the rate of manual transcription error in outpatient point-of-care testing.

Many point-of-care laboratory tests are manually entered into the electronic health record by ambulatory clinic staff, but the rate of manual transcription error for this testing is poorly characterized. Using a dataset arising from a duplicated workflow that created a set of paired interfaced and manually entered point-of-care glucose measurements, we found that 260 of 6930 (3.7%) manual entries were discrepant from their interfaced result. Thirty-seven of the 260 (14.2%) errors were discrepant by more than 20% and included potentially dangerous mistranscriptions. An additional 37 (14.2%) errors were due to inclusion of non-numeric characters. Staff-entered result flags deviated from the result flag generated in the laboratory information system in 5121 of 6930 (73.9%) pairs. These data demonstrate that clinically significant discrepancies for clinic-entered point of care results occurred at a rate of approximately 5 per 1000 results and they underline the importance of interfacing instruments when feasible.

Establishing evidence-based thresholds and laboratory practices to reduce inappropriate treatment of pseudohyperkalemia.

BACKGROUND: Unrecognized pseudohyperkalemia (PHK), defined as an artificial increase in measured potassium concentration, due to thrombocytosis and leukocytosis can lead to inappropriate patient treatment. Understanding the laboratory and patient characteristics that increase risk of PHK is key to preventing diagnostic errors. METHODS: Serum/plasma potassium results collected at 2 laboratories over 4years were selected based on blood cell counts collected within 24h and whole blood potassium concentrations determined within 2h of the serum/plasma sample. Differences between whole blood and serum or plasma potassium were compared as functions of platelet or leukocyte count, fit to linear models, and stratified based on leukemia diagnosis codes. Patients having a serum/plasma potassium concentration that was at least 1mEq/mL higher than the whole blood concentration were defined as having PHK. Based on this analysis, high-risk patients were prospectively identified and PHK risk was communicated to providers. Medication administration records were queried to compare rates of kayexalate use pre- and post-intervention. RESULTS: Approximately 14% of serum samples with platelet counts >500×109/L had a>1mEq/L increase relative to whole blood potassium. >25% of serum and plasma samples showed a>1mEq/L increase relative to whole blood potassium when leukocyte counts were >50×109/L. Patients with chronic lymphocytic leukemia and high WBC count demonstrated the highest rates of PHK. The rate of kayexalate administration prior to confirmatory testing decreased from 37% to 16% after the laboratory started verbally communicating the possibility of PHK to treating providers. CONCLUSIONS: According to our data, a leukocyte count threshold for plasma samples of 50×109/L is appropriate for indicating a high risk of PHK. Direct communication by the laboratory to the care team reduces inappropriate potassium lowering treatment in populations at high risk.

Preventing Genetic Testing Order Errors With a Laboratory Utilization Management Program.

OBJECTIVES: To characterize error rates for genetic test orders between medical specialties and in different settings by examining detailed order information. METHODS: We performed a retrospective analysis of a detailed utilization management case database, comprising 2.5 years of data and almost 1,400 genetic test orders. After review by multiple reviewers, we categorized order modifications and cancellations, quantified rates of positive results and order errors, and compared genetics with nongenetics providers and inpatient with outpatient orders. RESULTS: High cost or problems with preauthorization were the most common reasons for modification and cancellation, respectively. The cancellation rate for nongenetics providers was three times the rate for geneticists, but abnormal result rates were similar between the two groups. The approval rate for inpatient orders was not significantly lower than outpatient orders, and abnormal result rates were similar for these two groups as well. Order error rates were approximately 8% among tests recommended by genetics providers in the inpatient setting, and tests ordered or recommended by nongeneticists had error rates near 5% in both inpatient and outpatient settings. CONCLUSIONS: Clinicians without specialty training in genetics make genetic test order errors at a significantly higher rate than geneticists. A laboratory utilization management program prevents these order errors from becoming diagnostic errors and reaching the patient.

Comparison of label-free biosensing in microplate, microfluidic, and spot-based affinity capture assays.

Using both experimental assays and fluid-dynamic finite element simulation models, we directly compared the achievable performance limits of four distinct assay configurations for label-free detection of an analyte from a test sample on a biosensor surface. The assay configurations studied in this work included a biosensor incorporated into the bottom surface of a microplate well and a microfluidic channel. For each configuration, we compared assay performance for the scenario in which the entire bottom surface of the fluid-handling vessel is coated with capture ligands with assay performance for the scenario in which the capture ligands are applied in the form of localized spots. As a model system, we used detection of the protein biomarker tumor necrosis factor-alpha (TNF-alpha) using immobilized TNF-alpha capture antibody. Results show that the microfluidic assay format dramatically reduces the time required to establish a stable equilibrium. Spot-based assays are advantageous for microplate-based detection for reducing the time required for equilibrium sensor response. The results derived are generally applicable to any label-free biosensor technology and any ligand-analyte system with adjustable variables that include sensor mass density sensitivity, analyte-ligand adsorption/desorption rate constants, immobilized ligand density, flow channel geometry, flow rate, and spot size.

Photonic crystal enhanced cytokine immunoassay.

Photonic crystal surfaces are demonstrated as a means for enhancing the detection sensitivity and resolution for assays that use a fluorescent tag to quantify the concentration of an analyte protein molecule in a liquid test sample. Computer modeling of the spatial distribution of resonantly coupled electromagnetic fields on the photonic crystal surface are used to estimate the magnitude of enhancement factor compared to performing the same fluorescent assay on a plain glass surface, and the photonic crystal structure is fabricated and tested to experimentally verify the performance using a sandwich immunoassay for the protein Tumor Necrosis Factor-alpha (TNF-alpha). The demonstrated photonic crystal fabrication method utilizes a nanoreplica molding technique that allows for large-area inexpensive fabrication of the structure in a format that is compatible with confocal microarray laser scanners. The signal-to-noise ratio for fluorescent spots on the photonic crystal is increased by at least five-fold relative to the glass slide, allowing a TNF-alpha concentration of 1.6 pg/ml to be distinguished from noise on a photonic crystal surface. In addition, the minimum quantitative limit of detection on the photonic crystal surface is one-third the limit on the glass slide - a decrease from 18 pg/ml to 6 pg/ml. The increased performance of the immunoassay allows for more accurate quantitation of physiologically relevant concentrations of TNF-alpha in a protein microarray format that can be expanded to multiple cytokines.

Leaky-mode assisted fluorescence extraction: application to fluorescence enhancement biosensors.

Efficient recovery of light emitted by fluorescent molecules by employing photonic structures can result in high signal-to-noise ratio detection for biological applications including DNA microarrays, fluorescence microscopy and single molecule detection. By employing a model system comprised of colloidal quantum dots, we consider the physical basis of the extraction effect as provided by photonic crystals. Devices with different lattice symmetry are fabricated ensuring spectral and spatial coupling of quantum dot emission with leaky eigenmodes and the emission characteristics are studied using angle-resolved and angle-integrated measurements. Comparison with numerical calculations and lifetime measurements reveals that the enhancement occurs via resonant redirection of the emitted radiation. Comparison of various lattices reveals differences in the enhancement factor with a maximum enhancement factor approaching 220. We also demonstrate the first enhanced extraction biosensor that allows for over 20-fold enhancement of the fluorescence signal in detection of the cytokine TNF-alpha by a fluorescence sandwich immunoassay.

Application of photonic crystal enhanced fluorescence to a cytokine immunoassay.

Photonic crystal surfaces are demonstrated as a means for enhancing the detection sensitivity and resolution for assays that use a fluorescent tag to quantify the concentration of an analyte protein molecule in a liquid test sample. Computer modeling of the spatial distribution of resonantly coupled electromagnetic fields on the photonic crystal surface are used to estimate the magnitude of enhancement factor compared to performing the same fluorescent assay on a plain glass surface, and the photonic crystal structure is fabricated and tested to experimentally verify the performance using a sandwich immunoassay for the protein tumor necrosis factor-alpha (TNFalpha). The demonstrated photonic crystal fabrication method utilizes a nanoreplica molding technique that allows for large-area inexpensive fabrication of the structure in a format that is compatible with confocal microarray laser scanners. The signal-to-noise ratio for fluorescent spots on the photonic crystal is increased by at least 5-fold relative to the glass slide, allowing a TNF-alpha concentration of 1.6 pg/mL to be distinguished from noise on a photonic crystal surface. In addition, the minimum quantitative limit of detection on the photonic crystal surface is one-third the limit on the glass slide--a decrease from 18 to 6 pg/mL. The increased performance of the immunoassay allows for more accurate quantitation of physiologically relevant concentrations of TNF-alpha in a protein microarray format that can be expanded to multiple cytokines.