Readmissions in adult patients following hospitalization for influenza: a nationwide cohort study.

Background: Influenza epidemics are a major health care concern in the US. Influenza related complications can increase in-hospital complications, and readmissions following a hospitalization for influenza. We sought to determine the 30-day readmission rate, etiologies, outcomes, and healthcare burden of 30-day readmissions in adults hospitalized for influenza.

Methods: The 2014 US National Readmissions Database (NRD) was retrospectively analyzed to identify patients ≥18 years of age hospitalized for influenza and discharged between January and November 2014. We used this time frame as this was the most recent data available for analysis and included patients who had 30-day follow-up. Survey design based multivariable logistic regression models were used to identify factors associated with a 30-day readmission.

Results: Of the 46,117 patients who were hospitalized for influenza and survived to discharge, 4,721 (10.2%) patients had 5,275 30-day readmissions, estimated to 11.4 readmissions per 100 patients. Non-influenza pneumonia was the most common etiology of 30-day readmissions (10.4%) followed by sepsis (9.8%). The median costs of readmissions were $8,538 (IQR, $5,053-15,262), which were significantly higher than the median costs of their index hospitalizations [$7,863 (IQR, $4,875-13,212); P<0.001]. Around 6.5% of the patients died during a readmission.

Conclusions: Adult patients hospitalized for influenza had 11.4 30-day readmissions per 100 patients, most commonly for non-influenza pneumonia. Thirty-day readmissions were associated with higher costs of care and considerable mortality.