• Optimal serum ferritin level range: iron status measure and inflammatory biomarker

      DePalma, Ralph G; Hayes, Virginia W; O'Leary, Timothy J (Oxford University Press, 2021-05-28)
      This report provides perspectives concerning dual roles of serum ferritin as a measure of both iron status and inflammation. We suggest benefits of a lower range of serum ferritin as has occurred for total serum cholesterol and fasting blood glucose levels. Observations during a prospective randomized study using phlebotomy in patients with peripheral arterial disease offered unique insights into dual roles of serum ferritin both as an iron status marker and acute phase reactant. Robust positive associations between serum ferritin, interleukin 6 [IL-6], tissue necrosis factor-alpha, and high sensitivity C-reactive protein were discovered. Elevated serum ferritin and IL-6 levels associated with increased mortality and with reduced mortality at ferritin levels <100 ng mL-1. Epidemiologic studies demonstrate similar outcomes. Extremely elevated ferritin and IL-6 levels also occur in individuals with high mortality due to SARS-CoV-2 infection. Disordered iron metabolism reflected by a high range of serum ferritin level signals disease severity and outcomes. Based upon experimental and epidemiologic data, we suggest testing the hypotheses that optimal ferritin levels for cardiovascular mortality reduction range from 20 to 100 ng mL-1 with % transferrin levels from 20 to 50%, to ensure adequate iron status and that ferritin levels above 194 ng mL-1 associate with all-cause mortality in population cohorts.
    • Relative sensitivity of anterior nares and nasopharyngeal swabs for initial detection of SARS-CoV-2 in ambulatory patients: Rapid review and meta-analysis

      Zhou, Yaolin; O'Leary, Timothy J (Public Library of Science, 2021-07-20)
      Nasopharyngeal (NP) swabs are considered "gold standard" for diagnosing SARS-CoV-2 infections, but anterior nares or mid-turbinate swabs (nasal swabs) are often used. We performed a meta-analysis comparing the sensitivity of nasal and nasopharyngeal swabs against a composite reference standard for the initial diagnosis of SARS-CoV-2 infection in ambulatory patients. The study is registered on PROSPERO (CRD42020221827). Data sources included studies appearing between January 1, 2020 and March 20, 2021, identified by searches of PubMed, medRxiv and bioRxiv. Studies included at least 20 subjects who simultaneously provided nasal and nasopharyngeal specimens for reverse transcription-polymerase chain reaction testing, and for which confusion matrices could be constructed. Authors individually assessed studies for inclusion and compared assessments. Each author independently extracted all data elements; differences were reconciled by review of initial data sources. Extracted data included specimen site, patient characteristics, collection site, and confusion matrices comparing results for nasal and nasopharyngeal swabs. Assessed against a composite reference standard, anterior nares swabs are less sensitive (82% - 88%) than nasopharyngeal swabs (98%). For populations with 10% specimen positivity, the negative predictive values of all swab types were greater than 98%. Mid-turbinate and anterior nares swabs seem to perform similarly. The lower sensitivity associated with nasal swab SARS-CoV-2 diagnosis is justified by the ability to screen more patients and reduced personal protective equipment requirements. Our conclusions are limited by the small number of studies and the significant heterogeneity of study designs and study outcomes.
    • Relative Sensitivity of Saliva and Upper Airway Swabs for Initial Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Ambulatory Patients: Rapid Review

      O'Leary, Timothy J (Elsevier B.V., 2021-01-01)
      Saliva has been proposed as an alternative to upper airway swabs when testing for severe acute respiratory syndrome coronavirus 2. Although some studies have suggested higher viral loads and clinical sensitivity when testing saliva, studies have been relatively small and have given rise to contradictory results. To better understand the relative performance characteristics of saliva and upper airway samples, I performed a rapid systematic review (registered on PROSPERO as CRD42020205035), focusing on studies that included at least 20 subjects who provided diagnostic saliva and upper airway samples on the same day, which were tested by nucleic acid amplification methods and for which a confusion matrix could be constructed for based on a composite reference standard. Nineteen studies comprising 21 cohorts that met predetermined acceptance criteria were identified following a search of PubMed, medRxiv, and bioRxiv. Seven of these cohorts were incorporated into a meta-analysis using a random effects model, which suggests that nasopharyngeal swabs are somewhat more sensitive than saliva samples for the diagnosis of early disease in ambulatory patients, such as in drive-through centers or community health centers. Nevertheless, the difference is modest, and the reduced need for personal protective equipment for saliva sampling may justify the difference. Conclusions are limited by the significant heterogeneity of disease prevalence in the study populations and variation in the approaches to saliva sample collection.
    • Testing for Severe Acute Respiratory Syndrome-Coronavirus 2: Challenges in Getting Good Specimens, Choosing the Right Test, and Interpreting the Results

      Tu, Yuan-Po; O'Leary, Timothy J (Wolters Kluwer Health, 2020-11-01)
      OBJECTIVES: We explore ways to reduce errors in laboratory diagnosis of severe acute respiratory syndrome-coronavirus 2 infection by considering preanalytic, analytic, and postanalytic sources. To address preanalytic challenges, we first consider alternative anatomic sites for specimen collection, then discuss self-collection, alternative sampling devices, and transport media. Strengths and limitations of various analytic test systems are considered in the context of postanalytic challenges associated with making test results meaningful, specifically considering the complex relationship between "positive" test results and reproduction and shedding of intact virus. Finally, we provide recommendations regarding healthcare worker surveillance and release of patients with coronavirus disease 2019 from isolation. DATA SOURCES: Material was derived from a Webinar available to the public, manufacturer's websites, U.S. Food and Drug Administration, and Centers for Disease Control and Prevention websites and from both peer-reviewed papers identified by PubMed search and nonpeer-reviewed papers posted on Biorxiv and Medrxiv. Unpublished data came from the Washington State Department of Health. STUDY SELECTION: We included studies that compared diagnostic performance strategies without introducing bias due to use of an imperfect gold standard. Case series and case reports were included as necessary to illuminate the significance of results. DATA EXTRACTION: Data were extracted manually. DATA SYNTHESIS: Sensitivity, specificity, and CIs were computed from article data using a composite reference standard. Nucleic acid-based tests were assumed to perform at 100% specificity. CONCLUSIONS: Although sputum and bronchoalveolar lavage samples provide the highest diagnostic sensitivity for severe acute respiratory syndrome-coronavirus 2, nasopharyngeal, mid turbinate, and nasal specimens are suitable in most cases and require less use of personal protective equipment. When desired sampling materials are unavailable, alternatives may be substituted with no loss of performance. Both reverse transcriptase polymerase chain reaction tests and rapid nucleic acid-based tests offer good performance in most circumstances. Testing is not required to release most patients from isolation.