Background: Literature on the prognostic value of laboratory tests on patients hospitalized with COVID-19 is sparse.1-4 Based on available evidence our institution developed a protocol for care of patients admitted with COVID-19. In addition to routine labs (complete blood count, complete metabolic panel, venous lactate, etc.), the protocol recommends a set of COVID-specific daily lab tests including; d-Dimer, fibrinogen, ferritin, lactate dehydrogenase (LDH), creatinine kinase (CK), proBNP, troponin and C-reactive protein (CRP). The goal of the current study was to determine the prognostic value of admission COVID-specific labs beyond that provided by routine admission labs and vital signs.
Methods: We queried our institutions electronic health record for all adult (age 18 years) patients admitted between 3/13/2020 to 7/22/2020 with a primary, secondary or tertiary diagnosis of COVID-19 (U07.1 ICD-10 code). The study outcomes were inpatient mortality, an ICU stay during the hospitalization and length of hospitalization. We used multivariable logistic (mortality, ICU stay) and linear (length of hospitalization) regression to determine if initial COVID-specific admission labs had any prognostic value beyond that provided by vital signs and routine admission labs tests. In the multivariable models we included all routine admission labs and vital signs. COVID-specific admission labs were only included in the multivariable models if the p-value was < 0.05 in the univariable analysis.
Results: Table 1 shows patient characteristics. Similar to other studies, Latinx patients suffer a disproportionate burden from COVID-19 disease. For mortality, COVID-19 lab results did not provide additional prognostic value above that provided by admission labs and vitals (Table 2). For ICU stay (Table 3); CRP (OR=1.09, p < 0.001), LDH (OR = 1.20, p < 0.001) and d-Dimer (OR = 1.004, p = 0.047) provided additional prognostic information. For length of hospitalization; CRP > 100 and LDH > 900 increased length of stay by 0.64 (p < 0.001) and 0.63 (< 0.001) days; respectively and showed prognostic value above that provided by admission labs and vitals alone.
Conclusions: Our study showed that only 3 of 8 admission COVID labs recommended by our institution’s protocol have additional prognostic value beyond routine labs and vitals. The total cost of COVID-specific labs during the study period (3/14 to 7/22) was $110,122 and the cost of COVID-specific labs shown to have no prognostic value was $75,874 during the same time period. Extrapolated out to the end of calendar year 2020, then the total expense for COVID labs with no prognostic value is $169,124 to our institution. We are in the process of revising our protocol to only include COVID labs shown to have prognostic value for patient outcomes.