RESUMO
BackgroundCOronaVirus Disease 2019 (COVID-19) can be challenging to diagnose, because symptoms are non-specific, clinical presentations are heterogeneous, and false negative tests can occur. Our objective was to assess the utility of lymphocyte count to differentiate COVID-19 from influenza or community-acquired pneumonia (CAP). MethodsWe conducted a cohort study of adults hospitalized with COVID-19 or another respiratory infection (i.e., influenza, CAP) at seven hospitals in Ontario, Canada.The first available lymphocyte count during the hospitalization was used. Standard test characteristics for lymphocyte count (x109/L) were calculated (i.e., sensitivity, specificity, area under the receiver operating curve [AUC]). All analyses were conducting using R. ResultsThere were 869 hospitalizations for COVID-19, 669 for influenza, and 3009 for CAP. The mean age across the three groups was 67 and patients with pneumonia were older than those with influenza or COVID19, and approximately 46% were woman. The median lymphocyte count was nearly identical for the three groups of patients: 1.0 x109/L (interquartile range [IQR]:0.7,2.0) for COVID-19, 0.9 x109/L (IQR 0.6,1.0) for influenza, and 1.0 x109/L (IQR 0.6,2.0) for CAP. At a lymphocyte threshold of less than 2.0 x109/L, the sensitivity was 87% and the specificity was approximately 10%. As the lymphocyte threshold increased, the sensitivity of diagnosing COVID-19 increased while the specificity decreased. The AUC for lymphocyte count was approximately 50%. InterpretationLymphocyte count has poor diagnostic discrimination to differentiate between COVID-19 and other respiratory illnesses. The lymphopenia we consistently observed across the three illnesses in our study may reflect a non-specific sign of illness severity. However, lymphocyte count above 2.0 x109/L may be useful in ruling out COVID-19 (sensitivity = 87%).
RESUMO
BackgroundPatient characteristics, clinical care, resource use, and outcomes associated with hospitalization for coronavirus disease (COVID-19) in Canada are not well described. MethodsWe described all adult discharges from inpatient medical services and medical-surgical intensive care units (ICU) between November 1, 2019 and June 30, 2020 at 7 hospitals in Toronto and Mississauga, Ontario. We compared patients hospitalized with COVID-19, influenza and all other conditions using multivariable regression models controlling for patient age, sex, comorbidity, and residence in long-term-care. ResultsThere were 43,462 discharges in the study period, including 1,027 (3.0%) with COVID-19 and 783 (2.3%) with influenza. Patients with COVID-19 had similar age to patients with influenza and other conditions (median age 65 years vs. 68 years and 68 years, respectively, SD<0.1). Patients with COVID-19 were more likely to be male (59.1%) and 11.7% were long-term care residents. Patients younger than 50 years accounted for 21.2% of all admissions for COVID-19 and 24.0% of ICU admissions. Compared to influenza, patients with COVID-19 had significantly greater mortality (unadjusted 19.9% vs 6.1%, aRR: 3.47, 95%CI: 2.57, 4.67), ICU use (unadjusted 26.4% vs 18.0%, aRR 1.52, 95%CI: 1.27, 1.83) and hospital length-of-stay (unadjusted median 8.7 days vs 4.8 days, aRR: 1.40, 95%CI: 1.20, 1.64), and not significantly different 30-day readmission (unadjusted 8.6% vs 8.2%, aRR: 1.01, 95%CI: 0.72, 1.42). InterpretationAdults hospitalized with COVID-19 during the first wave of the pandemic used substantial hospital resources and suffered high mortality. COVID-19 was associated with significantly greater mortality, ICU use, and hospital length-of-stay than influenza.
