Influenza complications increase with obesity
19 August 2011
Obesity has been linked for the first time to a higher rate of hospitalisation for seasonal influenza prompting calls for people with a high body mass index (BMI) to be vaccinated against flu.
Canadian researchers found that obese individuals (BMI 30 kg/m² or over) were 45 per cent more likely to be hospitalised for respiratory illness compared with people whose weight was in the normal range (BMI 18.5-24.9 kg/m²). Severely obese individuals (BMI 35 kg/m² or over) were twice as likely to be hospitalised for respiratory illness as normal weight people.
The figures came from a study covering 12 influenza seasons, from 1996 to 2008, and 82,500 adults aged up to 64 years who responded to health surveys.
The researchers found that obese individuals were at increased risk of hospitalisation from any cause during flu seasons, but the association was greater for respiratory conditions than for other conditions (Clinical Infectious Diseases 2011; 53: 413-21).
In an editorial, experts from the US Centers for Disease Control and Prevention said while an association between obesity and influenza was notable during the H1N1 ('swine flu') pandemic, the Canadian study was the first to demonstrate such a link with seasonal influenza.
However the effect may have been overestimated if some medical conditions that carry a high risk for influenza complications, such as diabetes and neurological disorders, were not identified in the surveys, they said (Clin Infect Dis 2011; 53: 422-4).
Nevertheless, they concluded that as vaccination is the primary tool to prevent influenza infection, it "should be encouraged" in people who are obese or morbidly obese, irrespective of whether they have other illnesses.
Last Reviewed: 19 August 2011
- 1. Kwong JC, Campitelli MA, Rosella LC. Obesity and respiratory hospitalizations during influenza seasons in Ontario, Canada: a cohort study. Clin Infect Dis 2011; 53: 413-21. doi: 10.1093/cid/cir442. http://cid.oxfordjournals.org/content/53/5/413.long (accessed Aug 2011).
2. Jain S, Chaves SS. Obesity and influenza. Clin Infect Dis 2011; 53: 422-4. doi: 10.1093/cid/cir448. http://cid.oxfordjournals.org/content/53/5/422.full (accessed Aug 2011).
