Impact of obesity on influenza compared to pneumonia hospitalization outcomes.

Abstract

OBJECTIVES\nPrevious literature has suggested that obesity impacts mortality risk differently in bacterial versus viral infections. This study sought to further elucidate this association in pneumonia versus influenza.\n\n\nDESIGN\nRetrospective cohort study.\n\n\nSETTING AND PARTICIPANTS\nData were collected from the US Nationwide Readmission Database from 2013 to 2014.\n\n\nMETHODS\nPatients were categorized into three weight groups: normal weight (BMI 18.5-25.0 kg/m2), obese (BMI 30-40.0 kg/m2), and morbidly obese (BMI ≥ 40 kg/m2). To minimize confounding, we excluded patients with a history of smoking, alcoholism, or chronic wasting conditions, as suggested by the Global BMI Mortality Collaboration. To further isolate obesity from baseline differences across cohorts, we performed a three-way propensity matching analysis. The association between body weight and in-hospital all-cause 30-day mortality was assessed using Cox proportional hazard regression analysis.\n\n\nRESULTS\n132,965 influenza and 34,177 pneumonia hospitalizations were identified. For patients with influenza, obesity (hazard ratio [HR]: 1.51; 95% CI: 1.01-2.26) and morbid obesity (HR: 1.64; 95% CI: 1.10-2.44) were associated with higher in-hospital 30-day mortality compared to normal weight. For pneumonia, obesity (HR, 0.41; 95% CI, 0.20-0.84) and morbid obesity (HR, 0.49; 95% CI, 0.25-0.96) were associated with reduced 30-day mortality compared to normal weight.\n\n\nCONCLUSIONS AND IMPLICATIONS\nObesity may increase 30-day mortality risk during influenza hospitalization but provide mortality benefit in pneumonia, a divergent effect not adequately explained by lower admission threshold.