A recent paper reports a Case Fatality Ratio of 7.2% (compared to 2.3% reported from China)
This includes all data from the Italian National Institute of Health up to 17th March which included 1625 deaths of 22 512 cases.
The authors suggest three possible reasons:
2019 census data indicates 23% of Italy's population were >65 years at the time. When divided by age group, data shown below demonstrates fatality was higher for those >70 years old in Italy compared with China.
All patients who tested positive for SARS-CoV-2 had COVID-19 recorded as the cause of death due to issues with case definition for COVID-19. This may have included some patients with other primary causes of death.
The most severely affected were prioritised for testing.
Onder G, Rezza G, Brusaferro S. Case-Fatality Rate and Characteristics of Patients Dying in Relation to COVID-19 in Italy. JAMA. 2020 Mar 23. doi: 10.1001/jama.2020.4683. [Epub ahead of print]