Implementation of Clinical Decision Support Rules to Reduce Repeat Measurement of Serum Ionized Calcium, Serum Magnesium, and N-Terminal Pro-B-Type Natriuretic Peptide in Intensive Care Unit Inpatients.

BACKGROUND: We assessed the impact of clinical decision support (CDS) rules within the electronic health record for ionized calcium (iCa), serum magnesium (Mg), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in intensive care unit (ICU) inpatients at a large academic center. METHODS: A repeat order for measurement of iCa or Mg placed within 24 (iCa) or 48 (Mg) h of a previously nonactionable result, or additional orders for NT-proBNP beyond 1 within a single hospitalization, triggered a CDS pop-up alert showing the prior result and offering the opportunity to cancel the order or to place the order after entering an indication for repeat testing. The number of tests performed for each of these analytes and incidence of adverse clinical outcomes potentially associated with hypocalcemia or hypomagnesemia were compared between the 90-day period before CDS implementation and two 90-day periods immediately following. RESULTS: iCa test volumes decreased by 48%, Mg by 39%, and NT-proBNP by 28% in the 90-day period immediately following implementation and remained decreased by 54%, 49%, and 22%, respectively, during the following 90-day period (all P values <0.0002). Adverse clinical outcomes potentially associated with hypocalcemia or hypomagnesemia did not increase (all P-values >0.17). CONCLUSIONS: Implementation of CDS dramatically decreased repeat testing of iCa, Mg, and NT-proBNP without adversely impacting clinical outcomes in the ICU. Expansion of the rules from the ICU units to include the entire hospitalized patient population and expansion to additional analytes is expected to lead to further reductions in testing.

Using mass spectrometry to monitor monoclonal immunoglobulins in patients with a monoclonal gammopathy.

A monoclonal gammopathy is defined by the detection a monoclonal immunoglobulin (M-protein). In clinical practice, the M-protein is detected by protein gel electrophoresis (PEL) and immunofixation electrophoresis (IFE). We theorized that molecular mass could be used instead of electrophoretic patterns to identify and quantify the M-protein because each light and heavy chain has a unique amino acid sequence and thus a unique molecular mass whose increased concentration could be distinguished from the normal polyclonal background. In addition, we surmised that top-down MS could be used to isotype the M-protein because each immunoglobulin has a constant region with an amino acid sequence unique to each isotype. Our method first enriches serum for immunoglobulins followed by reduction using DTT to separate light chains from heavy chains and then by microflow LC-ESI-Q-TOF MS. The multiply charged light and heavy chain ions are converted to their molecular masses, and reconstructed peak area calculations for light chains are used for quantification. Using this method, we demonstrate how the light chain portion of an M-protein can be monitored by molecular mass, and we also show that in sequential samples from a patient with multiple myeloma the light chain portion of the M-protein was detected in all samples, even those negative by PEL, IFE, and quantitative FLC. We also present top-down MS isotyping of M-protein light chains using a unique isotype-specific fragmentation pattern allowing for quantification and isotype identification in the same run. Our results show that microLC-ESI-Q-TOF MS provides superior sensitivity and specificity compared to conventional methods and shows promise as a viable method of detecting and isotyping an M-protein.

An assessment of overutilization and underutilization of laboratory tests by expert physicians in the evaluation of patients for bleeding and thrombotic disorders in clinical context and in real time.

BACKGROUND: Diagnostic error is extremely common in the USA and likely around the world. A major reason for the diagnostic error is both the overutilization and the underutilization of laboratory tests. Using a panel of two to four experts in coagulation, test selection was reviewed in clinical context and in real time, and consensus determinations were made to derive conclusions about the extent of overutilization and underutilization. METHODS: Two hundred cases of patients being evaluated for bleeding or thrombotic issues were presented at each daily meeting of the diagnostic management team, and a review of each case for appropriate utilization of tests was completed. RESULTS: Two hundred randomly selected cases revealed 77.5% diagnostic errors (155 cases). Sixteen percent were associated with overutilization of laboratory tests, 44% were associated with underutilization, and 17.5% were associated with both. The annual cost burden estimated for overutilization alone in one institution of 450 beds was on the order of $20,000. The cost burden for the delay in diagnosis or the misdiagnosis in cases with underutilization is orders of magnitude greater ($200,000 or more), but it is impossible to determine the cost of a misdiagnosis in an individual case because it can produce many different clinical outcomes. CONCLUSIONS: This was a rare opportunity for experts in a given field to review cases in real time and in clinical context and provide immediately a consensus answer about test utilization. The results of this study show errors in test selection in nearly 75% of the cases evaluated.