Development, evaluation, and validation of machine learning models for COVID-19 detection based on routine blood tests

Cabitza, F.; Campagner, A.; Ferrari, D.; Di Resta, C.; Ceriotti, D.; Sabetta, E.; Colombini, A.; De Vecchi, E.; Banfi, G.; Locatelli, M.; Carobene, A.

Background: The rRT PCR test, the current gold standard for the detection of coronavirus disease (COVID19), presents with known shortcomings, such as long turnaround time, potential shortage of reagents, false-negative rates around 15/20%, and expensive equipment. The hematochemical values of routine blood exams could represent a faster and less expensive alternative. Methods: Three different training data set of hematochemical values from 1,624 patients (52% COVID19 positive), admitted at San Raphael Hospital (OSR) from February to May 2020, were used for developing machine learning (ML) models: the complete OSR dataset (72 features: complete blood count (CBC), biochemical, coagulation, hemogasanalysis and CO-Oxymetry values, age, sex and specific symptoms at triage) and two subdatasets (COVID specific and CBC dataset, 32 and 21 features respectively). 58 cases (50% COVID19 positive) from another hospital, and 54 negative patients collected in 2018 at OSR, were used for internal external and external validation. Results: We developed five ML models: for the complete OSR dataset, the area under the receiver operating characteristic curve (AUC) for the algorithms ranged from 0.83 to 0.90; for the COVID specific dataset from 0.83 to 0.87; and for the CBC dataset from 0.74 to 0.86. The validations also achieved good results: respectively, AUC from 0.75 to 0.78; and specificity from 0.92 to 0.96. Conclusions: ML can be applied to blood tests as both an adjunct and alternative method to rRT PCR for the fast and cost-effective identification of COVID19 positive patients. This is especially useful in developing countries, or in countries facing an increase in contagions.