Extended laboratory panel testing in the Emergency Department for risk-stratification of patients with COVID-19: a single centre retrospective service evaluation

ABSTRACT

BackgroundThe role of specific blood tests to predict poor prognosis in patients admitted with infection from SARS-CoV2 virus remains uncertain. During the first wave of the global pandemic, an extended laboratory testing panel was integrated into the local pathway to guide triage and healthcare resource utilisation for emergency admissions. We conducted a retrospective service evaluation to determine the utility of extended tests (D-dimer, ferritin, high-sensitivity troponin I, lactate dehydrogenase, procalcitonin) compared to the core panel (full blood count, urea & electrolytes, liver function tests, C-reactive protein). MethodsClinical outcomes for adult patients with laboratory-confirmed COVID-19 admitted between 17th March to 30st June 2020 were extracted, alongside costs estimates for individual tests. Prognostic performance was assessed using multivariable logistic regression analysis with 28-day mortality used as the primary endpoint, and a composite of 28-day intensive care escalation or mortality for secondary analysis. ResultsFrom 13,500 emergency attendances we identified 391 unique adults admitted with COVID-19. Of these, 113 died (29%) and 151 (39%) reached the composite endpoint. "Core" test variables adjusted for age, gender and index of deprivation had a prognostic AUC of 0.79 (95% Confidence Interval, CI 0.67 to 0.91) for mortality and 0.70 (95% CI 0.56 to 0.84) for the composite endpoint. Addition of "extended" test components did not improve upon this. ConclusionOur findings suggest use of the extended laboratory testing panel to risk stratify community-acquired COVID-19-positive patients on admission adds limited prognostic value. We suggest laboratory requesting should be targeted to patients with specific clinical indications.