Learning Pediatric Point-of-Care Ultrasound: How Many Cases Does Mastery of Image Interpretation Take?

OBJECTIVES: Using an education and assessment tool, we examined the number of cases necessary to achieve a performance benchmark in image interpretation of pediatric soft tissue, cardiac, lung, and focused assessment with sonography for trauma (FAST) point-of-care ultrasound (POCUS) applications. We also determined interpretation difficulty scores to derive which cases provided the greatest diagnostic challenges. METHODS: Pediatric emergency physicians participated in web-based pediatric POCUS courses sponsored by their institution as a credentialing priority. Participants deliberately practiced cases until they achieved diagnostic interpretation scores of combined 90% accuracy, sensitivity, and specificity. RESULTS: Of the 463 who enrolled, 379 (81.9%) completed cases. The median (interquartile range) number of cases required to achieve the performance benchmark for soft tissue was 94 (68-128); cardiac, 128 (86-201); lung, 87 (25-118); and FAST, 93 (68-133) (P < 0001). Specifically, cases completed to achieve benchmark were higher for cardiac relative to other applications (P < 0.0001 for all comparisons). In soft tissue cases, a foreign body was more difficult to diagnose than cobblestoning and hypoechoic collections (P = 0.036). Poor cardiac function and abnormal ventricles were more difficult to interpret with accuracy than normal (P < 0.0001) or pericardial effusion cases (P = 0.01). The absence of lung sliding was significantly more difficult to interpret than normal lung cases (P = 0.028). The interpretation difficulty of various FAST imaging findings was not significantly different. CONCLUSIONS: There was a significant variation in number of cases required to reach a performance benchmark. We also identified the specific applications and imaging findings that demonstrated the greatest diagnostic challenges. These data may inform future credentialing guidelines and POCUS learning interventions.

A Target Population Derived Method for Developing a Competency Standard in Radiograph Interpretation.

CONSTRUCT: For assessing the skill of visual diagnosis such as radiograph interpretation, competency standards are often developed in an ad hoc method, with a poorly delineated connection to the target clinical population. BACKGROUND: Commonly used methods to assess for competency in radiograph interpretation are subjective and potentially biased due to a small sample size of cases, subjective evaluations, or include an expert-generated case-mix versus a representative sample from the clinical field. Further, while digital platforms are available to assess radiograph interpretation skill against an objective standard, they have not adopted a data-driven competency standard which informs educators and the public that a physician has achieved adequate mastery to enter practice where they will be making high-stakes clinical decisions. APPROACH: Operating on a purposeful sample of radiographs drawn from the clinical domain, we adapted the Ebel Method, an established standard setting method, to ascertain a defensible, clinically relevant mastery learning competency standard for the skill of radiograph interpretation as a model for deriving competency thresholds in visual diagnosis. Using a previously established digital platform, emergency physicians interpreted pediatric musculoskeletal extremity radiographs. Using one-parameter item response theory, these data were used to categorize radiographs by interpretation difficulty terciles (i.e. easy, intermediate, hard). A panel of emergency physicians, orthopedic surgeons, and plastic surgeons rated each radiograph with respect to clinical significance (low, medium, high). These data were then used to create a three-by-three matrix where radiographic diagnoses were categorized by interpretation difficulty and significance. Subsequently, a multidisciplinary panel that included medical and parent stakeholders determined acceptable accuracy for each of the nine cells. An overall competency standard was derived from the weighted sum. Finally, to examine consequences of implementing this standard, we reported on the types of diagnostic errors that may occur by adhering to the derived competency standard. FINDINGS: To determine radiograph interpretation difficulty scores, 244 emergency physicians interpreted 1,835 pediatric musculoskeletal extremity radiographs. Analyses of these data demonstrated that the median interpretation difficulty rating of the radiographs was -1.8 logits (IQR -4.1, 3.2), with a significant difference of difficulty across body regions (p < 0.0001). Physician review classified the radiographs as 1,055 (57.8%) as low, 424 (23.1%) medium or 356 (19.1%) high clinical significance. The multidisciplinary panel suggested a range of acceptable scores between cells in the three-by-three table of 76% to 95% and the sum of equal-weighted scores resulted in an overall performance-based competency score of 85.5% accuracy. Of the 14.5% diagnostic interpretation errors that may occur at the bedside if this competency standard were implemented, 9.8% would be in radiographs of low-clinical significance, while 2.5% and 2.3% would be in radiographs of medium or high clinical significance, respectively. CONCLUSION(S): This study's novel integration of radiograph selection and a standard setting method could be used to empirically drive evidence-based competency standard for radiograph interpretation and can serve as a model for deriving competency thresholds for clinical tasks emphasizing visual diagnosis.

The Loss of ATRX Increases Susceptibility to Pancreatic Injury and Oncogenic KRAS in Female But Not Male Mice.

Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in North America, accounting for >30,000 deaths annually. Although somatic activating mutations in KRAS appear in 97% of PDAC patients, additional factors are required to initiate PDAC. Because mutations in genes encoding chromatin remodelling proteins have been implicated in KRAS-mediated PDAC, we investigated whether loss of chromatin remodeler ɑ-thalassemia, mental-retardation, X-linked (ATRX) affects oncogenic KRAS's ability to promote PDAC. ATRX affects DNA replication, repair, and gene expression and is implicated in other cancers including glioblastomas and pancreatic neuroendocrine tumors. The hypothesis was that deletion of Atrx in pancreatic acinar cells will increase susceptibility to injury and oncogenic KRAS. Methods: Mice allowing conditional loss of Atrx within pancreatic acinar cells were examined after induction of recurrent cerulein-induced pancreatitis or oncogenic KRAS (KRASG12D ). Histologic, biochemical, and molecular analysis examined pancreatic pathologies up to 2 months after induction of Atrx deletion. Results: Mice lacking Atrx showed more progressive damage, inflammation, and acinar-to-duct cell metaplasia in response to injury relative to wild-type mice. In combination with KRASG12D, Atrx-deficient acinar cells showed increased fibrosis, inflammation, progression to acinar-to-duct cell metaplasia, and pre-cancerous lesions relative to mice expressing only KRASG12D. This sensitivity appears only in female mice, mimicking a significant prevalence of ATRX mutations in human female PDAC patients. Conclusions: Our results indicate the absence of ATRX increases sensitivity to injury and oncogenic KRAS only in female mice. This is an instance of a sex-specific mutation that enhances oncogenic KRAS's ability to promote pancreatic intraepithelial lesion formation.