Pre-existing conditions are associated with COVID patients’ hospitalization, despite confirmed clearance of SARS-CoV-2 virus
Authors: Pawlowski Colin , Venkatakrishnan AJ , Ramudu Eshwan , Kirkup Christian , Puranik Arjun , Kayal Nikhil , Berner Gabriela , Anand Akash , Barve Rakesh , O’Horo John C. , Badley Andrew D. , Soundararajan Venky 
Published: October 2020

The current diagnostic gold-standard for SARS-CoV-2 clearance from infected patients is two consecutive negative PCR test results. However, there are anecdotal reports of hospitalization from protracted COVID complications despite such confirmed viral clearance, presenting a clinical conundrum. We conducted a retrospective analysis of 266 COVID patients to compare those that were admitted/re-admitted post-viral clearance (hospitalized post-clearance cohort, n=93) with those that were hospitalized pre-clearance but were not re-admitted post-viral clearance (non-hospitalized post-clearance cohort, n=173). In order to differentiate these two cohorts, we used neural network models for the augmented curation of comorbidities and complications with positive sentiment in the EHR physician notes. In the year preceding COVID onset, acute kidney injury (n=15 (16.1%), p-value: 0.03), anemia (n=20 (21.5%), p-value: 0.02), and cardiac arrhythmia (n=21 (22.6%), p-value: 0.05) were significantly enriched in the physician notes of thehospitalized post-clearance cohort. This study highlights that these specific pre-existing conditions are associated with amplified hospitalization risk in COVID patients, despite their successful SARS-CoV-2 viral clearance. Our finding that pre-COVID anemia amplifies risk of post-COVID hospitalization is particularly concerning given the high prevalence and endemic nature of anemia in many low- and middle-income countries (per the World Bank definition; e.g. India, Brazil), which are unfortunately also seeing high rates of SARS-CoV-2 infection and COVID-induced mortality. This study motivates follow-up prospective research into the specific risk factors we have identified that appear to predispose some patients towards the after effects of COVID-19.

Article summary – Strengths and limitations of this study

This is the first study at a major healthcare center analyzing risk factors for post-viral clearance hospitalization of COVID-19 patients.

This analysis uses augmented curation methods to identify complications and comorbidities from the physician notes, rather than relying upon ICD codes.

The statistical analysis identifies specific comorbidities in the year preceding PCR diagnosis of SARS-CoV-2 which are associated with increased rates of post-viral clearance hospitalization.

The dataset used for this study is limited to a single healthcare system, so the underlying clinical characteristics of the study population are biased to reflect the clinical characteristics of individuals that receive medical treatment in certain regions of the United States (Arizona, Florida, Minnesota).

In this study, we use the first of two consecutive negative PCR tests to estimate the viral clearance date for each patient, however the true viral clearance date for each patient is unknown.