3.2 Causes of hospitalization
Table 2 indicates the causes of hospitalization for all patients. Pneumonia was the most common cause representing 55% of all cases. The breakdown of pneumonia category was community-acquired (44.3%), nursing and healthcare-associated (10.2%), and hospital-acquired (0.5%). The second-most common cause (27.3%) was a poor general condition due to the influenza infection itself. Other causes include exacerbation of underlying chronic respiratory disease (chronic obstructive pulmonary disease [COPD], interstitial pneumonia, bronchial asthma, and so on), heart failure, renal failure, and miscellaneous. Rhabdomyolysis and encephalopathy were recognized in 1.0% and 0.6%, respectively. Thirty-nine patients (4.2%) were admitted due to social indication (the very elderly, those living alone, or those unable to reach medical facilities easily).