Following favourable clinical trial results the use of statins was recommended in 1998 for patients with, or at high risk of developing cardiovascular disease. Using a threshold of cholesterol >5.0mmol/l or the presence of diabetes it was estimated (Feely, 1999)¹ that >80% of such populations should receive an "evidence based" statin.

We evaluated the influence of study results and guidelines on the prescribing patterns of statins in the General Medical Services scheme (GMS), which provides free health services, including medicines. The database records basic demographic information on patients and details on all items dispensed. The GMS database from the Eastern Regional Health Authority (344,270 eligible GMS patients) was used to identify a cohort of patients over 15 years of age, who had been prescribed statins, in order to investigate prescribing trends during the period January 1998 - December 2002. Patients with ischaemic heart disease (IHD) were identified by prescription of both aspirin and nitrate in any month and patients with diabetes (DM) identified by prescription of any insulin, insulin analogue or oral hypoglycaemic therapy. Logistic regression analysis was used to quantify statin prescribing in patients with IHD and DM and adjusted odds ratios (OR) and 95% Confidence Intervals presented. Results showed increased prescribing of each statin over time (test for linear trend p<0.0001). Pravastatin was the most frequently prescribed, followed by atorvastatin and simvastatin; atorvastatin showed the greatest increased rate over time. An increase in the dose of statins prescribed was noted over time (test for trend p<0.01), chiefly due to increases in pravastatin dose. However all were still well below the recommended dose based on clinical trial results. Statins were prescribed more frequently in patients with IHD and DM compared with the total GMS population (44% vs.14% at Dec. 2002); the annual increase in usage was statistically significant for each group throughout the study (test for linear trend p<0.0001, Table 1). However, statins were only prescribed to 52% of IHD patients and 40% of DM patients by Dec. 2002. Patients aged 45-64 years were more likely to receive statins, compared with those aged 65 years.

These findings suggest that the beneficial effects of statins shown in clinical studies, especially relating to drug type and dosage may not have not been adequately conveyed to prescribers, therefore these benefits may not be achieved in practice.Table 1.Trends in prescribing of statins in IHD and DM patients during study period (1998-2002).

1 Feely J, (1999), Atherosclerosis 147 (suppl 1): 31-37.