COVID-19 Resuming Normal Practice: Risk Stratification and Scoring Systems

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Open article published on MedShr: 28th October 2020
Last updated: 28th October 2020

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Since the Covid-19 pandemic has swept the globe, and after initial strict lockdown measures, governments and workplaces have had to adapt to attempt some return to normality. Although life and work have changed dramatically, with many shifting their work to home from offices, risk stratification tools have been needed to quantify biological risk to individuals. This is helpful both in workplaces, but also in clinical settings, where scoring systems can be used with patients presenting with Covid-19 like illnesses, to make predictions about the likely trajectory of their illness.

Risk stratification for populations

In the United Kingdom, the Chief Medical Officer (CMO) commissioned NHS Digital to produce a list of vulnerable people at increased risk of complications from COVID-19, who should be shielded for at least 12 weeks [1].  A data linkage analysis was undertaken to identify individuals who should undertake ‘shielding’, and take extra precautions above normal public health measures of maintaining social distance. This resulted in the formation of two groups:

  1. “At Risk” – a larger group of approximately 19 million, normally at risk from influenza – should practice strict social distancing

  2. “At high risk” – a smaller sub-group of approximately 1.5 million, defined by CMO – should practice complete “shielding”

Clinical inclusion criteria deeming individuals "high risk" were determined and led to inclusion in the shielded patients list (SPL). They were as follows:

  • Solid organ transplant recipients who remain on long term immune suppression therapy

  • Cancer undergoing active chemo/ radiotherapy or radical radiotherapy for lung cancer

  • People having immunotherapy or other continuing antibody treatments for cancer

  • People having other targeted cancer treatments which affect the immune system, such as protein kinase or PARP inhibitors

  • People with cancers of the blood or bone marrow

  • People who have had bone marrow or stem cell transplants in the last 6 months, or still taking immunosuppression drugs

  • People with severe respiratory conditions including  severe asthma and severe COPD

  • Cystic Fibrosis, idiopathic pulmonary Fibrosis, etc. Need to go straight through. Regardless of treatment.

  • People with rare diseases and inborn errors of metabolism that significantly increase the risk of infections (such as SCID, homozygous sickle cell)

  • People on immunosuppression therapies sufficient to significantly increase risk of infection

  • People who are pregnant with significant congenital heart disease

Adapted from ref [5]

Risk assessments at work

Health and Safety Executive (HSE) have published national guidance on how to make workplaces Covid-secure during the pandemic [2]. The key measures to mitigate risk which have been recommended include: a thorough risk assessment by employers, social distancing, cleaning, hygiene and handwashing, close collaboration with employees, working from home where possible, and special protections for vulnerable workers. To aid these decisions, a formal risk assessment matrix was also published [3], and extensive guidance [4] provided on practical measures that could be implemented to mitigate risks, including: putting in place social distancing measures, staggering shifts and providing additional handwashing facilities.

In addition to these measures, the British Medical Association created an objective risk stratification (ORS) tool for individuals not already identified as “vulnerable” by the NHS Digital Shielded Patient List [5]. This list included factors such as age, sex, ethnicity, diabetes, obesity, cardiovascular disease, pulmonary disease, rheumatological conditions, cancer or immunosuppression (figure 1). On the basis of these factors, a score is then attributed to determine risk.

Scoring systems

Clinical determination of at risk individuals is vital to tailor treatment, to guide management and optimise resource allocation. A study published recently in the British Medical Journal (BMJ) proposes the 4C (Coronavirus Clinical Characterisation Consortium) Mortality Score, as an easy-to-use and valid prediction tool for in-hospital mortality [6]. The score categorises patients as being at low, intermediate, high, or very high risk of death (Figure 2).

The key benefit of such scoring systems to clinicians is to guide and support management decisions about recognising when care should be escalated.

Adapted from ref [6]

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[1] Accessed online at:             

[2] Accessed online at:

[3] Accessed online at:

[4] Accessed online at:

[5] Development of an Objective Risk Stratification Tool to facilitate workplace assessments of healthcare workers when dealing with the CoViD-19 pandemic. W David Strain, Janusz Jankowski, Angharad Davies, Peter MB English, Ellis Friedman, Helena McKeown, Su Sethi, Mala Rao OBE. Accessed online at:

[6] Knight SR, Ho A, Pius R, Buchan I, Carson G, Drake TM, Dunning J, Fairfield CJ, Gamble C, Green CA, Gupta R, Halpin S, Hardwick HE, Holden KA, Horby PW, Jackson C, Mclean KA, Merson L, Nguyen-Van-Tam JS, Norman L, Noursadeghi M, Olliaro PL, Pritchard MG, Russell CD, Shaw CA, Sheikh A, Solomon T, Sudlow C, Swann OV, Turtle LC, Openshaw PJ, Baillie JK, Semple MG, Docherty AB, Harrison EM; ISARIC4C investigators. Risk stratification of patients admitted to hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: development and validation of the 4C Mortality Score. BMJ. 2020 Sep 9;370:m3339. doi: 10.1136/bmj.m3339. PMID: 32907855.

Article by Dr Adam Ali, MedShr Open Editorial Team, Medical Education Fellow

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