Epidemiology and outcomes of hospitalization of influenza in the cancer population in Taiwan

Purpose To assess the disease and economic burden of hospitalization of influenza among patients with cancer in Taiwan using a complete medical database for Taiwanese patient records from 1999 to 2005. Methods The diagnosis of influenza-related infections was extracted as any ICD-9, the principal diagnosis code for influenza, bronchopneumonia, or pneumonia caused by a non-specific organism and the diagnosis code for cancer. From these two diagnosis codes, we estimated excess cases during the influenza season for each year and stratum. Results During the 7-year-study period, a total of 69,411 hospitalizations were identified for their principal diagnosis of influenza. The average lengths of hospital stay (LOS) and artificial ventilation procedures were 10.2, 8.9, 13.2, 5.0 days, and 0.7, 1.5, 3.5, 0.1% among patients with a cancer diagnosis, a chronic disease diagnosis, cancer combined with a chronic disease diagnosis, and the general population, respectively. Patients with cancer had higher rates of hospitalization with influenza-related infection than those without cancer diagnosis ( P < 0.0001). Conclusion Among hospitalizations of influenza, those with a diagnosis of cancer and of chronic disease were reported to have a longer LOS and higher frequency of artificial ventilation procedures compared to those without a secondary diagnosis of cancer or chronic disease. Immunization among patients with cancer and their contacts is recommended to reduce the disease and economic burden in Taiwan.