OBJECTIVES: To identify subjects affected by Chronic Obstructive Pulmonary Disease (COPD) in a local health authority of approximately 441 thousand inhabitants situated in Campania, a region in the southwest of Italy.METHODS: METHODS: A retrospective naturalistic longitudinal study was conducted using record linkage between administrative health services databases (drug prescription, hospital admissions, demographic). We enrolled subjects with greater than or equal to 45 years old who had during the period 2006/2007 an hospital admission for Chronic Bronchitis (ICD-9 cod.491) and/or received drugs chronic prescription for obstructive diseases from the R03 Anatomical Therapeutic Chemical Classification group.Subjects with a hospital admission for asthma (ICD-9 cod.493) and/or a prescription of drugs with indication for an allergenic disease (R03DC, R03BC) were excluded. RESULTS:A cohort of 12,212 COPD affected patients (51.5% males) was selected, 11,726 received drug prescription and 1,405 were hospitalized. Only the 7 % of the cohort was recognized from both electronic databases. Strikingly, the 39% of subjects selected with a hospital admission for COPD did not received drugs chronic prescription.The estimated prevalence in adult population (>= 45 years old) was 6,3% and was higher in males (7.1%) than in females (5.7%). Stratifying by age the prevalence was highest in subjects with more than 75 years and is twice in males. CONCLUSIONS:From the administrative database it was possible to provide an estimation of the prevalence of COPD in a particular area of Campania. Further research will validate our results, in particular, in future we will be able to describe therapeutic profiles of patients and we will try to understand why a high percentage of subjects with an hospital admission for Chronic Bronchitis receive no medication.