COVID-19 Risk factors

Introduction

On March 17th, 2020, when I first searched the academic database, PubMed, for “COVID-19” and “humans”, there were 99 results (Ref 1). The same search today (18th April) generates 1,101 results. As I reported in the note on tests, COVID-19 papers are being published while going through peer review, as it is deemed so important to share knowledge as soon as possible on this evolving topic (Ref 2). Papers need to pass editorial consideration before peer review, so an element of inspection is still taking place.

Among these papers, we have the first comprehensive review of the literature. This paper set out to find and review the most current, accredited, studies pertaining to the basic sciences of SARS-CoV-2 (COVID-19). If you are looking for an academic overview, this is a good place to start, although some aspects of the paper will date more quickly than others (Ref 3).

There has also been what I believe to be the first meta-analysis, published on 8th April 2020 (Ref 4). This meta-analysis asks the important question – Does comorbidity increase the risk of patients with COVID-19? This is the topic being reviewed this week. We hear that people with underlying conditions are at greater risk with COVID-19, but what exactly does this mean? Greater risk of being hospitalized? Becoming critical? And which underlying conditions are of more concern than others? Might there be some underlying conditions that are less of a concern? And perhaps others that should be driving protection advice more carefully?

Evidence available

The evidence on COVID-19 is emerging in pockets and it is country/location driven, as observations in a particular region are examined, documented, and then shared more widely.

The earliest, decent-sized, summary of characteristics of patients with COVID-19 inevitably came from China (Ref 5). It reported on 1,099 patients with lab-confirmed COVID-19, from 552 hospitals in 30 provinces and other discrete regions in mainland China until the end of January 2020. The patients were on average (median) 47 years old and 58% were male. Only 5% of patients were admitted to Intensive Care Units (ICU); 2.3% underwent invasive mechanical ventilation and 1.4% died. One of the most interesting findings of this paper was that white blood cell count was abnormally low in 83% of the patients on admission.