Cross sectional survey of effectiveness of lipid lowering drugs in reducing serum cholesterol concentration in patients in 17 general practices
Hippisley-Cox J., Cater R., Pringle M., Coupland C.
Objective: To compare the effectiveness of lipid lowering drugs in lowering serum cholesterol concentrations. Design: Cross sectional study. Setting: 17 practices within 17 primary care groups in Trent region, United Kingdom. Participants: Patients aged 35 years or over taking lipid lowering drugs and with at least two serum cholesterol concentrations recorded on computer. Main outcome measures: Proportion of patients achieving serum cholesterol concentration of ≤5 mmol/l and mean percentage reduction in serum cholesterol concentration. Results: 1353 of 2469 (54.8%) patients receiving lipid lowering treatment had a last recorded serum cholesterol concentration of ≤5 mmol/l. Significantly more patients taking statins achieved the target value for serum cholesterol (5 mmol/l) than those taking fibrates (1307 (57%) v 46 (26%); P < 0.0001). Atorvastatin and simvastatin were the most effective drugs in achieving the target. Lipid lowering drugs differed significantly for pretreatment serum cholesterol concentration, most recent cholesterol concentration, and the associated percentage reduction. Atorvastatin and simvastatin achieved the greatest percentage reduction in serum cholesterol concentrations (30.1%, 95% confidence interval 28.8% to 31.4% and 28.0%, 26.7% to 29.3%, respectively). Although the mean serum cholesterol concentrations in this unselected population tended to be higher than those in clinical trials, the percentage reduction was consistent with the trials. Conclusion: The ability of individual statins to lower serum cholesterol concentration varied, with atorvastatin and simvastatin being the most effective. The percentage reductions agreed with those of randomised controlled trials indicating likely benefits in unselected patients in primary care. As the initial serum cholesterol concentrations were higher than those in randomised controlled trials, target serum cholesterol values of ≤5 mmol/l may be unrealistic even for patients on the most efficacious drugs. Also, the higher initial concentrations could mean that the absolute reduction in cardiovascular risk in primary care patients is greater than thought.