Prognostic value of labs ordered on patients hospitalized with COVID-19

Background: Hospitalists at our institution have taken on most non-intensive care unit (ICU) coronavirus disease 2019 (COVID-19) care. Based on sparse research, our institution developed a protocol for ordering labs for this patient population, including routine admission labs in addition to eight COVID-19-specific daily labs. The study goal is to determine if COVID-19-specific admission labs have any prognostic value beyond that provided by routine admission labs and vitals, and costs of labs with no prognostic value.Methods: We retrospectively reviewed adult patients admitted with COVID-19 from 3/2020 to 7/2020. Outcomes were mortality, ICU stay, and length of hospitalization. Multivariable logistic and linear regression were used to determine if COVID-19-specific admission labs have any prognostic value beyond that provided by vitals and routine admission labs. COVID-19-specific labs were d-Dimer, fibrinogen, ferritin, LDH, CK, pro-BNP, troponin, and CRP. Multivariable models included all routine admission labs and vitals. COVID-19-specific admission labs were included in the multivariable models if the p-value was <0.05 in the univariable analysis.Results: 331 patients met study criteria, inpatient mortality was 13.0%, 52.4% of patients required ICU stays and the average length of hospitalization was 8.9 days. COVID-19-specific labs showed no additional prognostic value for mortality. CRP, LDH, and d-Dimer provided additional prognostic information for ICU stay. CRP≥100 mg/dL and LDH≥900 U/L were associated with increased length of hospitalization.Conclusion: Only 3 of 8 admission COVID-19-specific labs recommended by our institution's protocol had additional prognostic value beyond that provided by routine labs and vitals. The total cost of non-prognostic COVID-19-specific labs during the study period was $75,874.