Background Influenza disproportionately affects individuals with underlying comorbidities. Long-term follow-up studies have shown that patients with cancer with influenza have higher mortality. However, very little is known about the in-hospital mortality and cardiovascular outcomes of influenza infection in cancer hospitalisations.

Methods We compared the in-hospital mortality and cardiovascular outcomes in patients with cancer with and without influenza by screening the National Inpatient Sample from 2015 to 2017. A total of 9 443 421 hospitalisations with any cancer were identified, out of which 14 634 had influenza while 9 252 007 did not. A two-level hierarchical multivariate logistic regression analysis adjusted for age, sex, race, hospital type and relevant comorbidities was performed.

Results The group with cancer and influenza had higher in-hospital mortality (OR 1.08; 95% CI 1.003 to 1.16; p=0.04), acute coronary syndromes (OR 1.74; 95% CI 1.57 to 1.93; p<0.0001), atrial fibrillation (OR 1.24; 95% CI 1.18 to 1.29; p<0.0001) and acute heart failure (OR 1.41; 95% CI 1.32 to 1.51; p<0.0001).

Conclusion Patients with cancer affected by influenza have higher in-hospital mortality and a higher prevalence of acute coronary syndrome, atrial fibrillation and acute heart failure.