Charlson Comorbidity Index and Outcome of Cardiopulmonary Resuscitation in Geriatric Patients in Hong Kong

The goal of this observational study is to learn about the factors affecting the outcome (survival) of cardiopulmonary resuscitation in older persons in a hospital. The main questions it aims to answer are: * Whether age would affect outcome * Whether Charlson Comorbidity Index would affect outcome * Whether the conditions (e.g. heart rhythm) immediately before resuscitation would affect survival. Researchers would compare the patients who deceased with the patients who survived.