Evaluation of a calcium, magnesium and phosphate clinical ordering tool in the emergency department.

OBJECTIVE: We developed a clinical tool comprising patient risk factors for having an abnormal calcium (Ca), magnesium (Mg) or phosphate (PO4) level. We hypothesized that patients without a risk factor do not require testing. This study examined the tool's potential utility for rationalizing Ca, Mg and PO4 ordering in the emergency department (ED). METHODS: We undertook a retrospective observational study in a single metropolitan ED. Patients aged 18 years or more who presented between July and December 2019 were included if they had a Ca, Mg or PO4 test during their ED stay. Demographic and clinical data, including the presence of risk factors, were extracted from the medical record. The primary outcome was a clinically significant abnormal Ca, Mg or PO4 level (>0.2 mmol/l above or below the laboratory reference range). RESULTS: Calcium, Mg and PO4 levels were measured on 1426, 1296 and 1099 patients, respectively. The positive and negative predictive values and likelihood ratios of the tool identifying a patient with a Ca level > 0.2 mmol/l outside the range were 0.05, 0.99, 1.59 and 0.41, respectively. The values for Mg were 0.02, 1.00, 1.44 and 0.35 and those for PO4 were 0.15, 0.93, 1.38 and 0.57, respectively. The majority of patients not identified as having an abnormal level did not receive electrolyte correction treatment. Application of the tool would have resulted in a 35.8% cost reduction. CONCLUSION: The tool failed to predict a very small proportion of patients (approximately 1%) with an abnormal Ca or Mg level and for whom it would have been desirable to have these levels measured. It may help rationalize Ca and Mg ordering and reduce laboratory costs.

Author and journal self-citation in Emergency Medicine original research articles.

OBJECTIVE: To determine author and journal self-citation rates in a sample of original emergency medicine (EM) research articles. METHODS: We undertook a retrospective observational study of original research articles published in 2019 in the top six English language general EM journals. Data comprised the total numbers of articles, citations, authors and self-citations for each author (author self-citations) as well as the number of articles in the reference list that had been previously published in the same journal (journal self-citations). RESULTS: 3213 individual authors and 581 articles were examined. Most authors did not self-cite at all although 62 self-cited five or more times in a single article. The mean (SD) and median (IQR) numbers of individual author self-citations/article/year were 0.6 (1.3) and 0 (0-1), respectively. Overall, author self-citations accounted for 2.4% of all cited articles. There was a weak positive but significant correlation between the number of individual author self-citations/article/year and the number of articles published by the author (r = 0.38, p < 0.001). There was no correlation between the journal impact factor (IF) and the author self-citation rate (r = 0.14, p = 0.79). The journals differed significantly in their author self-citation rates (p < 0.001). Annals of Emergency Medicine had the highest journal self-citation rate at 8.1% (95%CI 7.0%-9.2%) self-citations/100 citations/year, almost twice that of some other journals. There was a large but non-significant positive correlation between the journal IF and journal self-citation rates (r = 0.78, p = 0.07). CONCLUSION: Both author and journal self-citation rates in the articles examined are relatively low compared to other medical and scientific disciplines.