Prevalence estimates for diabetes mellitus, treated diabetes, ischaemic heart disease, heart failure and COPD from each data source. Crude prevalence estimates for diabetes mellitus, treated diabetes, ischaemic heart disease, heart failure and COPD in 5 Italian regions, according to administrative data (Admin) and clinical GP data (GP) and, for diabetes and COPD only, the National Health Survey (Sur). For diabetes mellitus estimates from administrative data adjusted for ascertainment are also presented (Rec). On the left column prevalence is represented by box plots of the distribution of the disease prevalence in GP practices: the central line is the median value, the box covers the interquartile range, while wiskers range from a minimum to a maximum value except for some observations which are detected as outliers and are representes as single dots or diamonds; comparison is only betweem GP and Admin data sources. On the right column prevalence is represented as global estimate. Date: 1 January 2009 Population: male and females, aged 16+.