Delayed Antiviral Treatment May Increase Influenza Severity in Obese Patients

CDC Declares Flu Epidemic After Death of 15 Children
CDC Declares Flu Epidemic After Death of 15 Children
Disease severity was higher in obese patients during the 2011-2012 and 2012-2013 influenza seasons.

SAN DIEGO — Severity of influenza appeared to be higher in obese patients hospitalized during the 2011–2012 and 2012–2013 influenza seasons, according to results of a prospective study presented at ID Week 2015.

“Notably, we found that late treatment with oseltamivir, outside of the CDC-recommended 48-hour window, was associated with increased rates of pneumonia and ICU admission,” reported lead study author Emily T. Martin, MPH, PhD. “It is critical to consider confounding by timing of antivirals when evaluating risk factors for severe influenza infection.”

During the 2009 influenza A/H1N1 pandemic, individuals who were obese had increased disease severity and mortality. Researchers from the University of Michigan School of Public Health in Ann Arbor, and colleagues set out to determine influenza outcomes and risk factors for lower-pulmonary disease (LPD) and other severe complications, among obese patients. 

The team prospectively identified hospitalized patients with laboratory-confirmed influenza (n=55) during the 2011–2012 and 2012–2013 flu seasons. Almost half (47%) had Class I–III Obesity, defined as a BMI ≥30.

Treatment with oseltamivir was started in patients with obesity faster upon symptom onset (median, 2 days vs 3 days; mean 3.3 vs 5.2 days; P=.04). 

After adjusting for administration of antivirals within 2 days of symptom onset, researchers found obesity was associated with intensive care unit admission (odds ratio [OR]=6.02, 95% CI, 1.1-34.5; P=.04). Lower pulmonary disease was numerically higher as well, but did not reach statistical significance (OR=3.4; 95% CI, 0.9-12.7).

Obese patients had shorter duration of stay after controlling for the timely administration of antivirals (2.1 less days; 95% CI, 0.2–3.6; P=.03), Dr Martin noted.

“Late antiviral administration was related to ICU admissions (OR 7.5, 95% CI: 1.02, 54.5; P=0.047) and lower-pulmonary disease (OR=5.8; 95% CI, 1.4-24.3; P=.02) after adjusting for factors such as poorer health status, obesity, steroid use, and diabetes,” she reported.


  1. Martin ET, Evans R, Archer C, Petrie JG, Arshad S, Kaye K. Poster 495. Influenza, Obesity and Timely Administration of Oseltamivir: A Prospective Study of Patient Outcomes. Presented at: ID Week 2015; Oct. 7-11, 2015; San Diego.

This article originally appeared on MPR