Prompt identification of the clinical status and severity of COVID-19 can be a challenge in the emergency department (ED), as the clinical severity of the disease is variable, real-time reverse-transcription PCR (RT-PCR) results may not be immediately available, and imaging findings appear approximately 10 days after the onset of symptoms. There is currently no set of simple, readily available and fast battery of tests that can be used in the ED as prognostic factors. The purpose was to study laboratory test results in patients with COVID-19 at hospital emergency admission and to evaluate the results in non-survivors and their potential prognostic value. A profile of laboratory markers was agreed with the ED providers based on the International Federation of Clinical Chemistry and Laboratory Medicine recommendation of its usefulness, which was made in 218 patients with COVID-19. Non-survivors were significantly older, and the percentage of patients with pathological values of creatinine, albumin, lactate dehydrogenase (LDH), C reactive protein, prothrombin time, D-dimer, and arterial blood gas, PaO2/FIO2 and satO2/FIO2 indices were significantly higher among the patients with COVID-19 who died than those who survived. Patients who died also presented higher neutrophil counts. Among all studied tests, albumin and LDH were independent prognostic factors for death. The results of the study show pathology in nine laboratory markers in patients with COVID-19 admitted in the ED, valuable findings to take into consideration for its prompt identification when there is no immediate availability of RT-PCR results.
- blood proteins
- diagnostic techniques and procedures
- medical laboratory science
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- blood proteins
- diagnostic techniques and procedures
- medical laboratory science
Prompt identification of the clinical status and severity of COVID-19 can be a challenge in the emergency department (ED), as the clinical severity of the disease is variable1; real-time reverse-transcription PCR (RT-PCR) results may not be immediately available; and imaging findings appear approximately 10 days after the onset of symptoms.2 There is currently no set of simple, readily available and fast battery of tests that can be used in the ED as COVID-19 risk factors.3–5
Our purpose was to study laboratory test results in patients with COVID-19 at hospital emergency admission and their potential prognostic value. We hypothesised that there could be significant differences in stat laboratory tests between survivors (finally did not die) and non-survivors (finally died).
A retrospective cohort to study COVID-19 cases was conducted. Data were retrospectively collected from 12 March to 20 May 2020. The clinical laboratory is located in a 370-bed suburban university community hospital that serves the population of the health department (234 551 inhabitants). The stat laboratory is independent but located in the main laboratory and receives samples from inpatients and patients in the ED. Laboratory requests are generated online, and the reports are sent electronically from the laboratory information system (LIS) (iGestLab) to the patient’s electronic medical record. The samples were delivered from the ED to the laboratory by pneumatic tube or hand delivery immediately after collection. ED care providers can automatically consult the report via the intranet.
Blood specimens obtained from 218 patients admitted in the ED, who ultimately were diagnosed with COVID-19, were received for laboratory testing. COVID-19 diagnoses were confirmed by positive RT-PCR assay using Cobas 6800 (Roche Diagnostics, Barcelona, Spain), in nasopharyngeal or oropharyngeal swab specimens that were sent to a reference laboratory, an RT-PCR centralised and specialised laboratory in our health department, and the results were obtained within 24–48 hours. A profile of laboratory markers was agreed with the ED providers based on the International Federation of Clinical Chemistry and Laboratory Medicine recommendations.6–8
Biochemistry tests were measured using Dimension RxL Max (Siemens Healthcare Diagnostics, Barcelona Spain), haematology tests by means of XT4000 (Sysmex Corporation, Barcelona, Spain), arterial blood gases (ABGs) using ABL 800 (Radiometer, Madrid, Spain) and coagulation test by ACLTOP300 (Werfen, Barcelona, Spain). All assays had successfully passed daily internal quality control and monthly external quality controls. All ABG analyses were performed in the laboratory by trained personnel. No sample was analysed using point of care analyser.
Initial laboratory results and survival status were collected from LIS and patient medical records. We defined two groups, survivors and non-survivors.
Descriptive statistics were presented as median and IQR, and percentages for continuous data and categorical data. The differences in laboratory values between groups were assessed using Mann-Whitney U test. A two-sided p≤0.05 rule was used as the criterion for rejecting the null hypothesis of no difference. A binary multiple logistic regression was performed to evaluate the relevant risk factors. Bonferroni correction was applied owing to multiple testing. Statistical analyses were conducted by means of Statistical Package for the Social Sciences V.22.
A summary of the results is provided in table 1. Twelve laboratory markers presented altered values in more than 50% of the patients, with C reactive protein (CRP), which was above the reference range in 85.2%, being the most frequently altered. Lactate dehydrogenase (LDH) was elevated in 81.2%, and neutrophil:lymphocyte ratio was above the values specified for COVID-193 in 72.5% of patients, with COVID-19 at initial emergency admission. ABG, PaO2:FIO2 and satO2:FIO2 ratios were decreased in 72.7% and 89.6%, respectively, and serum albumin in 71.5% of the cohort.
Non-survivors were significantly older and were more likely to present with elevated values of creatinine, albumin, LDH, CRP, prothrombin time and D-dimer than those who survived (p<0.05) (table 1). Patients who died also presented higher neutrophil counts and decreased ABG PaO2/FIO2 and satO2/FIO2 indices.
Among all studied tests, albumin (OR 0.407, 95% CI 0.202 to 0.819) and LDH (OR 1.003, 95% CI 1.001 to 1.005) were independent risk factors for death (R2 0.25, R2 albumin 0.11 and R2 LDH 0.09).
In our study, 100% of patients with COVID-19 who eventually died presented with elevated LDH and 93.1% presented with low albumin at admission, both markers being independent risk factors for death (figure 1).
The results and percentage of altered markers, of a battery of laboratory markers, can be used for a prompt preidentification of patients with COVID-19, when there is no immediate availability of RT-PCR result. Serum albumin, an outcome predictor in hospital emergency medical admissions,9 was more frequently decreased in patients with COVID-19 who did not survive.
The study had certain limitations. Ferritin and other laboratory markers as cytokines were not measured as these were not included in the stat laboratory menu. Time from admission to death or other clinical parameters not described in the study were not collected.
In conclusion, albumin and LDH were independent risk factors for death in patients with COVID-19 at hospital emergency admission. Measurement of both laboratory markers in such patients appears to be very relevant for patient assessment and prognosis. Further studies might be required to confirm these findings.
Patient consent for publication
The study was approved by the hospital research committee.
The authors express their deep gratitude to all the clinical laboratory staff.
Handling editor Tahir S Pillay.
Contributors All co-authors have seen and agree with the contents of the manuscript and have no conflicts of interest. We certify that the submission is original work and it has not been submitted for consideration elsewhere.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.