Evaluation of the prescription and utilization patterns of statins in an Italian local health unit during the period 1994-2003

Objectives The prescription pattern of statins in the Local Health Unit (LHU) of Treviso (northern Italy) over a 10-year period was evaluated, with the aim of evaluating the persistence with and adherence to therapy. Methods Data on 21,393 subjects who received at least one prescription for statins during the period between January 1, 1994 and December 31, 2003 were retrieved from the LHU database in order to track the pharmacological history of individual patients. The data included age, sex, drug formulation, strength, number of drug packages prescribed, and prescription date. The adopted indicators for drug utilization included the Defined Daily Dose (DDD), the Received Daily Dose (RDD), and a surrogated Prescribed Daily Dose (sPDD), extrapolated from available prescription data. An Adherence to Therapy Index (ATI) was calculated from the ratio between the amount of drug actually prescribed and the amount of sPDD. Based on the ATI, patients were grouped into non-adherent, poor-adherent, and good-adherent groups. The distribution of adherence level among patient-age classes and statin-prescribed patients in primary or secondary prevention was evaluated. Results All drug-utilization indicators showed an increase in statin use over the study period in terms of both the number of prescribed patients and the sPDD. Persistence with and adherence to therapy remained low, with a 50% discontinuation rate in the first year, and persistent patients did not follow the therapy regularly. Patients in secondary prevention were the most adherent to their drug regimen, although only 41% of these had a good compliance. Conclusions Our findings suggest an increase in statin use which is, however, accompanied by poor patient persistence with and adherence to statin therapy.