Flu-related Hospitalization Risk Increases Based on Weight

Patients with influenza or similar illnesses who are overweight or underweight are more likely to be hospitalized for their illness, a new study has found.  The observational cohort study included data on 4,778 hospitalized and outpatient participants, of whom 2,053 (43.0%) patients had severe influenza-like illness (ILI); 778 (16.3%) had influenza, 2,636 (55.2%) tested positive for other viral respiratory pathogens, and 1,364 (28.5%) did not test positive for any isolated respiratory virus.  When compared with normal-weight adults, influenza patients had a greater risk of hospitalization if they were underweight (odds ratio [OR]: 5.20), obese (OR: 3.18), or morbidly obese (OR: 18.40). Obese adults were also significantly more likely than those of a normal weight to be hospitalized if they had H1N1 as opposed to H3N2 and B (obese OR: 8.96 vs 1.35, morbidly obese OR: 35.13 vs 5.58, respectively). Underweight and morbidly obese adults with coronavirus, metapneumovirus, parainfluenza, and rhinovirus also had a greater chance of hospitalization (underweight OR 4.07, morbidly obese OR: 2.78). ILI of any cause was at least somewhat more likely to lead to hospitalization for underweight and morbidly obese patients than normal-weight patients.  “The risk follows a ‘U’‐shaped curve, where individuals at both extremes (ie, those that are underweight or morbidly obese) were more likely to develop severe ILI when compared with normal‐weight, overweight, or obese individuals,” the researchers wrote. “The increased risk of underweight and morbidly obese adults was stronger for influenza‐positive adults compared with those positive for other respiratory viruses or negative for any respiratory viruses.”  One of the study’s limitations is that it only included patients who sought medical attention for their symptoms. It also did not prove a causal relationship between body mass and risk of infection.  The study authors concluded that “our findings suggest that adults, who are underweight or morbidly obese, even if they do not have chronic conditions that increase the risk of influenza‐related complications, may be at increased risk of developing severe disease due to seasonal influenza infection as well as other respiratory viral infections. Clinicians should keep a patient’s body mass index in mind when evaluating risk and deciding on a course of treatment.”  How does Obesity Affect Influenza Risks?  FDA Approves First Flu Antiviral in Almost Two Decades  High Dose Flu Shot More Effective in RA Patients  AAP, CDC Recommend Flu Shot for Everyone Aged Six Months and Older  Source: Influenza and Other Respiratory Viruses