Metric analysis

New metric measures patient’s risk of developing severe symptoms

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Risk Rating System

Japan’s National Center for Global Health and Medicine (NCGM) and other institutions have created a simple clinical score to measure a coronavirus patient’s risk of developing severe symptoms. The metric will allow caregivers to prioritize the hospitalization of patients who need it most.

During the recent fifth wave of infection in Japan, the country’s medical system was overwhelmed by an unprecedented number of cases. Many patients have been forced into self-isolation and some have died without receiving proper treatment.

The researchers analyzed data from around 4,500 patients hospitalized between June and September 2020 during the second wave of infection. They identified the characteristics of moderate and severe cases where patients needed oxygen and created a risk score model to predict severity.

Rating

The metric is based on factors such as age, weight, and gender. For example, a man in the age group 40-64 receives 1 point. If he has a body mass index, or BMI, greater than 25, he receives 2 additional points. If he is diabetic, he gets another point.

The score is also adjusted for symptoms exhibited during illness with the coronavirus. A patient who experiences a fever of 37.5 degrees Celsius or higher receives 2 points. Shortness of breath is 2 points, while cough and fatigue are 1 point each.

Third wave analysis

The researchers verified the metric by checking data from cases recorded in the winter of 2020, during the third wave of infection. They found that 23% of patients aged 40 to 64 with a combined score of 5 became seriously ill. This figure increased to 76% when the combined score was 10.

Researchers say patients with a combined score above 5 should be classified as high risk when the virus is spreading rapidly. They add that these patients should be closely monitored and taken to medical facilities as soon as possible.

“If cases start to rise again and the number of people in home isolation increases, we hope the risk score can be used to effectively find patients at high risk of becoming seriously ill and help them get the treatment they need,” said Yamada Gen, a researcher at NCGM who helped create the metric.

He added: “The barometer does not cover all risks, but it could help determine if you belong to the risk group.”

Risk score by age group

The risk measure divides people into three age groups: 18-39, 40-64 and 65+.

18-39 years old

  • Men: 1 point
  • 30 years or more: 1 point
  • BMI from 23 to 29.9: 1 point
  • BMI of 30 or more: 2 points
  • Cancer patients: 3 points
  • Patients with fevers of 37.5 degrees Celsius or higher: 2 points
  • Patients who wheeze while breathing: 2 points
  • Patients with shortness of breath: 1 point

People in this age group who score 6 or more are at risk of developing severe symptoms as the virus spreads rapidly.

40-64 years old

  • Men: 1 points
  • 50-59 years old: 1 point
  • 60-64 years old: 3 points
  • BMI of 25 or more: 2 points
  • Diabetic patients: 1 point
  • Patients with fevers of 37.5 degrees Celsius or higher: 2 points
  • Patients who cough: 1 point
  • Patients with shortness of breath: 2 points
  • Patients experiencing fatigue: 1 point

People in this age group who score 5 or more are at risk of developing severe symptoms as the virus spreads rapidly.

65 or older

  • 75 years or older: 2 points
  • BMI of 25 or more: 2 points
  • People who have suffered a cardiac arrest: 2 points
  • Patients with cerebrovascular disease: 1 point
  • Diabetic patients: 2 points
  • Hypertensive patients: 2 points
  • Patients with fevers of 37.5 degrees Celsius or higher: 4 points
  • Patients who cough: 1 point
  • Patients with shortness of breath: 4 points

People in this age group who score 3 or more are at risk of developing severe symptoms as the virus spreads rapidly.

This information is accurate as of October 21, 2021.

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