Weight may affect the risk of flu hospitalization
08 December, 2018
According to a recent study, individuals may be more likely to be hospitalized due to the flu or another respiratory virus if they are underweight or at the higher end of the obesity scale.
Observational data for the study came from six hospitals in Mexico, and they covered 4,778 people with symptoms of a flu-like illness.
Some of these people received their treatment in the hospital, and some did as outpatients.
The results of the study showed that:
- 43 percent of the people had a severe flu-like illness
- 16.3 percent tested positive for flu
- 55.2 percent tested positive for another respiratory virus
- 28.5 percent "had no respiratory virus isolated"
When the scientists plotted the risk of hospital admission against people's body mass index (BMI), for adults, it formed a "U" shape on the graph.
The lowest risk of hospitalization was for those with a BMI in the "normal" weight range, and the highest risk was for those in the lowest and highest BMI ranges.
Children — which the researchers defined as all those under the age of 19 years — made up 32 percent of the people in the study. The scientists saw no clear link, however, between BMI and severe flu-like illness risk in this group.
The senior author of the study is Dr. John H. Beigel. He works for Leidos Biomedical Research Inc., a firm that operates National Laboratory facilities for the National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, MD. The other authors are from the NIAID and participating hospitals in Mexico.
The journal Influenza and Other Respiratory Viruses has now published a paper on this study.
BMI and obesity
A person's BMI is their weight in kilograms divided by the square of their height in meters. Because it is easy to measure, researchers often use BMI to explore weight-related health risks at the population level or in very large groups.
The Centers for Disease Control and Prevention (CDC) define BMI ranges for adults as:
- underweight is a BMI of less than 18.5
- normal weight is a BMI of 18.5–24.9
- overweight is a BMI of 25–29.9
- obesity is a BMI of 30 and higher
A similar system exists for children and adolescents aged 0–19 years, except that the cutoff values depend on age and sex.