High Body Mass Index as a Risk Factor for Hospitalization Due to Influenza A Case-Control Study

The authors conducted a case-control study to determine the association between body mass index and risk of hospitalization due to influenza. The researchers matched laboratory-confirmed hospitalized influenza patients with laboratory-confirmed outpatients and an outpatient control group during the 2009-10 and 2010-11 influenza seasons. They found an approximate five-fold increase in risk of hospitalization for those with a body mass index between 35 and 40 kg/m2 compared to those of normal weight. They also found significantly increased risk of hospitalization for those with a body mass index between 30 and 34.9 kg/m2 who are unvaccinated and under 65 years of age, underscoring the importance of influenza vaccination for these populations.