LAUSR

Obesity was identified as a risk factor for severe influenza during the 2009 influenza A(H1N1)pandemic, but evidence of this association has been mixed since. Post‐pandemic antiviral treatment guidelines may have increased antiviral treatment among obese individuals. A prospective study of adults hospitalized with laboratory‐confirmed influenza in Detroit, Michigan in 2011‐2012 and 2012‐2013 was conducted. Patient information was collected from interviews and medical chart abstraction. Obese (BMI ≥ 30) and non‐obese (BMI < 30) participants were compared. Late antiviral treatment (>2 days from symptom onset), obesity (30 ≤ BMI < 40), and morbid obesity (BMI ≥ 40) were evaluated as predictors of lower respiratory tract disease (LRD), ICU admission, and length of stay (LOS) using logistic regression and inverse probability weighted models. Forty‐eight participants were included in the study after exclusions and all patients received antiviral treatment. Participants who were obese were significantly more likely to have a cough and to take steroids than non‐obese participants, and had a shorter time from hospital admission to antiviral treatment (median time from admission to treatment of 0 days for obese patients and 1 day for non‐obese patients [P = 0.001]). In all models, late antiviral treatment was associated with increased odds of LRD (OR: 3.9 [1.1,15.9] in fully adjusted model). After adjustment for treatment timing, the odds of ICU admission (OR: 6.4 [0.8,58.2] to 7.9 [0.9, 87.1]) and LRD (OR: 3.3 [0.5, 23.5] to 4.0 [0.6, 35.0]) associated with morbid obesity increased. Obese individuals were treated with antivirals earlier than others. Late antiviral treatment was associated with severe influenza in the hospital.