Volume 2, Issue 1

Diagnostic errors are common and costly, but difficult to detect. “Trigger” tools have promise to facilitate detection, but have not been applied specifically for inpatient diagnostic error. We performed a scoping review to collate all individual “trigger” criteria that have been developed or validated that may indicate that an inpatient diagnostic error has occurred. We searched three databases and screened 8568 titles and abstracts to ultimately include 33 articles. We also developed a conceptual framework of diagnostic error outcomes using real clinical scenarios, and used it to categorize the extracted criteria. Of the multiple criteria we found related to inpatient diagnostic error and amenable to automated detection, the most common were death, transfer to a higher level of care, arrest or “code”, and prolonged length of hospital stay. Several others, such as abrupt stoppage of multiple medications or change in procedure, may also be useful. Validation for general adverse event detection was done in 15 studies, but only one performed validation for diagnostic error specifically. Automated detection was used in only two studies. These criteria may be useful for developing diagnostic error detection tools.

Background: Neurological emergencies often pose diagnostic challenges for emergency physicians because these patients often present with atypical symptoms and standard imaging tests are imperfect. Misdiagnosis occurs due to a variety of errors. These can be classified as knowledge gaps, cognitive errors, and systems-based errors. The goal of this study was to describe these errors through review of quality assurance (QA) records. Methods: This was a retrospective pilot study of patients with neurological emergency diagnoses that were missed or delayed at one urban, tertiary academic emergency department. Cases meeting inclusion criteria were identified through review of QA records. Three emergency physicians independently reviewed each case and determined the type of error that led to the misdiagnosis. Proportions, confidence intervals, and a reliability coefficient were calculated. Results: During the study period, 1168 cases were reviewed. Forty-two cases were found to include a neurological misdiagnosis and twenty-nine were determined to be the result of an error. The distribution of error types was as follows: knowledge gap 45.2% (95% CI 29.2, 62.2), cognitive error 29.0% (95% CI 15.9, 46.8), and systems-based error 25.8% (95% CI 13.5, 43.5). Cerebellar strokes were the most common type of stroke misdiagnosed, accounting for 27.3% of missed strokes. Conclusions: All three error types contributed to the misdiagnosis of neurological emergencies. Misdiagnosis of cerebellar lesions and erroneous radiology resident interpretations of neuroimaging were the most common mistakes. Understanding the types of errors may enable emergency physicians to develop possible solutions and avoid them in the future.

Background : An estimated 1.2 million people in the US have an acute myocardial infarction (AMI) each year. An estimated 7% of AMI hospitalizations result in death. Most patients experiencing acute coronary symptoms, such as unstable angina, visit an emergency department (ED). Some patients hospitalized with AMI after a treat-and-release ED visit likely represent missed opportunities for correct diagnosis and treatment. The purpose of the present study is to estimate the frequency of missed AMI or its precursors in the ED by examining use of EDs prior to hospitalization for AMI. Methods : We estimated the rate of probable missed diagnoses in EDs in the week before hospitalization for AMI and examined associated factors. We used Healthcare Cost and Utilization Project State Inpatient Databases and State Emergency Department Databases for 2007 to evaluate missed diagnoses in 111,973 admitted patients aged 18 years and older. Results : We identified missed diagnoses in the ED for 993 of 112,000 patients (0.9% of all AMI admissions). These patients had visited an ED with chest pain or cardiac conditions, were released, and were subsequently admitted for AMI within 7 days. Higher odds of having missed diagnoses were associated with being younger and of Black race. Hospital teaching status, availability of cardiac catheterization, high ED admission rates, high inpatient occupancy rates, and urban location were associated with lower odds of missed diagnoses. Conclusions : Administrative data provide robust information that may help EDs identify populations at risk of experiencing a missed diagnosis, address disparities, and reduce diagnostic errors.

Background: Routine liver function tests (LFTs) are central to serum testing profiles, particularly in community medicine. However there is concern about the redundancy of information provided to requesting clinicians. Large quantities of clinical laboratory data and advances in computational knowledge discovery methods provide opportunities to re-examine the value of individual routine laboratory results that combine for LFT profiles. Methods: The machine learning methods recursive partitioning (decision trees) and support vector machines (SVMs) were applied to aggregate clinical chemistry data that included elevated LFT profiles. Response categories for γ-glutamyl transferase (GGT) were established based on whether the patient results were within or above the sex-specific reference interval. Single decision tree and SVMs were applied to test the accuracy of GGT prediction by the highest ranked predictors of GGT response, alkaline phosphatase (ALP) and alanine amino-transaminase (ALT). Results: Through interrogating more than 20,000 individual cases comprising both sexes and all ages, decision trees predicted GGT category at 90% accuracy using only ALP and ALT, with a SVM prediction accuracy of 82.6% after 10-fold training and testing. Bilirubin, lactate dehydrogenase (LD) and albumin did not enhance prediction, or reduced accuracy. Comparison of abnormal (elevated) GGT categories also supported the primacy of ALP and ALT as screening markers, with serum urate and cholesterol also useful. Conclusions: Machine-learning interrogation of massive clinical chemistry data sets demonstrated a strategy to address redundancy in routine LFT screening by identifying ALT and ALP in tandem as able to accurately predict GGT elevation, suggesting that GGT can be removed from routine LFT screening.

Background: While the faecal immunochemical test for haemoglobin (FIT) is an important screening tool to detect gastrointestinal bleeding, false-negative cases resulting from the enterobacterial degradation of haemoglobin (Hb) have emerged. When faecal Hb tests have given false-negative results, it is considered that digestive bleeding diseases can be detected by measuring faecal transferrin (Tf), which is less susceptible to enterobacterial degradation. This study evaluated the benefit of measuring both Hb and Tf as markers of blood in the faeces during a large-scale colorectal cancer screening trial in Japan. Methods: We screened 12,255 participants, i.e., 8223 men and 4032 women, for faecal Hb and Tf using a Discrete Clinical Chemistry Analyser NS-Plus C15 system. Results: Among the 1232 participants with positive test results for blood, 417 were detected based solely on Tf, which increased the positive rate from 6.7% to 10.1%. The Hb and Tf concentrations were not correlated directly, thereby suggesting that Tf can detect a positive group that differs from that detected based on Hb. The positive rate for Tf alone was significantly higher in women (4.9%) compared with men (2.7%) (p<0.0001), which may be explained by the significantly higher constipation complaint rate in the Tf-positive group compared with the haemoglobin-only-positive group (p=0.0069). Conclusions: The results of this large-scale colorectal cancer screening study suggest that analysing both Hb and Tf using an NS-Plus system should be beneficial for subjects who are missed by conventional Hb testing alone.

Background : There are some problematic results in determination of differential renal function (DRF) by means of Tc-99m DMSA renal scintigraphy in hydronephrotic kidneys. In this study the classical method (CM) and unit area methods (UAM) in the estimation of DRF in unilateral hydronephrosis before and after intervention were compared. Methods : Twenty patients (12 M, 8 F; mean: 42.6±18.5 years old) who were candidates for surgery or intervention because of unilateral hydronephrosis were the subjects of this study. All the patients were evaluated by Tc-99m DMSA scintigraphy before and 3–6 months after the intervention. In order to estimate DRF both CM and UAM (obtained by division of the counts including the kidney ROI to pixel of the same ROI) were performed. Bland-Altman analyses were performed in order to compare the DRF values obtained from both methods. Results : The agreement between CM and UAM was poor in the preoperative estimation, however, the agreement was good after the operation or intervention. Conclusions : In this study it seems that DRF estimation with CM in unilateral hydronephrosis might be problematic in the determination of surgery thus UAM might be introduced as the method of choice in the determination of DRF in unilateral hyronephrosis.

Background: Methylmalonic acid (MMA) is a functional marker of vitamin B12 status and a valuable diagnostic tool. The gas chromatography mass spectrometry (GCMS) MMA assay has been used for decades in clinical studies. Methods: In this study, we compared a newly developed liquid chromatography tandem mass spectrometry assay for MMA (ClinMass ® Complete Kit) with the GCMS method and further measured other relevant vitamin B12 markers (homocysteine, total B12 and holotranscobalamin) to validate the new liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) method. For this purpose, 138 samples that were sent to our routine laboratory total B12 assay were used. Results: The GCMS and LC-MS/MS assays showed a strong correlation (r=0.92, p<0.001) particularly at low holoTC levels (deficiency is more probable). Forty six cases had MMA>300 nmol/L with both methods. Only five subjects showed MMA GCMS>300 nmol/L, but MMA LC-MS/MS≤300 nmol/L. However, the LC-MS/MS method showed a slightly better correlation with other B12 markers (holoTC, total B12). In addition, the LC-MS/MS method offers several advantages over the GCMS method, such as saving time and costs, precision, flexibility and popularity in modern labs. Conclusions: The new LC-MS/MS assay for MMA showed an excellent correlation to the GCMS method. The two methods showed similar agreements with other vitamin B12 markers.

We describe here the case of a 84-year-old woman under warfarin therapy for atrial fibrillation, who was admitted to the Emergency Department for severe gluteal hemorrhage. Blood samples were drawn after patient admission and transported within 20 min to the laboratory. Results of laboratory testing revealed a markedly increased value of international normalized ratio and extremely low values of serum sodium (60 mmol/L) and potassium (1.4 mmol/L). A second serum sample was collected approximately 2 h after the former, showing normal values of both sodium (145 mmol/L) and potassium (3.5 mmol/L). The analysis of the specimen collected upon patient admission revealed the presence of a small, transparent fibrin gel in the serum, which was partially aspirated by the sample probe of the instrument. This case underscores the importance that serum samples need to be allowed to clot completely prior to centrifugation and analysis, especially those collected from patients under anticoagulant treatment.