Dynamic modeling of hospitalized COVID-19 patients reveals disease state dependent risk factors

Abstract The global pandemic of the SARS-CoV-2 coronavirus has significantly strained hospital resources worldwide. Improved understanding of the COVID-19 disease trajectory for patients requiring hospitalization would allow for the development of more targeted preventative, diagnostic and therapeutic strategies. A covariate-dependent, continuous-time hidden Markov model with four states (moderate-illness, severe-illness, discharged, and deceased) was used to model the dynamic progression of COVID-19 during the course of hospitalization. All model parameters were estimated using the electronic health records of 1,362 patients from ProMedica Health System admitted between March 20, 2020 and December 29, 2020 with a positive nasopharyngeal PCR test for SARS-CoV-2. Demographic characteristics, co-morbidities, vital signs and laboratory test results were retrospectively evaluated to predict clinical progression and outcomes. Several patient-level covariates were associated with differential impacts on the risk of progression. Specifically, while being male, being black or having a medical co-morbidity were all associated with an increased risk of progressing from the moderate to severe disease state, these factors resulted in a decreased risk of transitioning from the severe to the deceased disease state. Body mass index (BMI) alone was not found to be associated with an increased risk of disease progression, while higher age was associated with an increased risk in progressing from moderate to severe and from severe to deceased states. Regardless of the differential risk profiles, all covariates considered other than BMI and asthma were associated with an overall increased risk of transitioning to the deceased state. Recent studies have not included analyses of the temporal progression of COVID-19, making the current study a unique modeling-based approach to understand the dynamics of COVID-19 in hospitalized patients. Such dynamic risk stratification models have the potential not only to improve clinical outcomes in COVID-19, but also a myriad of other acute and chronic diseases that, to date, have largely been assessed only by static modeling techniques.