Elevated risk of severe COVID-19 outcomes among underweight patients in Japan: A national registry-based study

Area of Science:

• Public Health
• Epidemiology
• Infectious Disease Epidemiology

Background:

• This study investigated the association between Body Mass Index (BMI) categories (underweight, normal, overweight) and COVID-19 severity in a large cohort of Japanese hospitalized patients.
• Utilizing the COVIREGI-JP database, the research analyzed data from 46,291 patients aged 20-89 years to assess disease severity based on the most intensive treatment received.

Discussion:

• The findings indicate that both underweight (BMI < 18.5) and overweight (BMI ≥ 25) individuals exhibit significantly higher risks of severe COVID-19 and mortality compared to those with a normal BMI (20.1-24.9).
• The risk was particularly elevated for underweight individuals during periods of Omicron variant predominance, suggesting a heightened vulnerability.
• The study controlled for sex and age group, providing adjusted odds ratios to quantify these risks.

Key Insights:

• Underweight (BMI < 18.5) is associated with increased odds of severe COVID-19 (OR: 1.88 for men, 1.59 for women) and death.
• Overweight (BMI ≥ 25) is also linked to higher risks of severe COVID-19 (OR: 1.38 for men, 1.87 for women) and death.
• Underweight individuals faced exceptionally high risks during Omicron predominance (OR: 2.41 for men, 2.96 for women).

Outlook:

• These results underscore the critical importance of considering BMI, especially underweight status, in predicting COVID-19 outcomes.
• Public health strategies may need to incorporate nutritional status assessments for vulnerable populations to mitigate severe disease.
• Further research could explore the biological mechanisms underlying the increased susceptibility in underweight individuals to COVID-19.