What is already known about this subject: * Statins reduce cholesterol concentrations and cardiovascular events in randomized clinical trials. * Much less is known about their impact in the setting of normal care.
What this study adds: * This is the first study to assess the effectiveness of lipid-lowering treatment in the general population. * We have also estimated the resultant impact on major vascular events. * We have examined the actual and potential impact of lipid-lowering treatment.
Aims: To evaluate the impact of lipid-lowering treatment on cholesterol concentrations in the setting of normal care.
Methods: This was a retrospective review of all cholesterol measurements made in Tayside, Scotland, between 1993 and 2002, linked to dispensed prescribing data for lipid-lowering drugs. It was conducted in the setting of normal care and included all patients who underwent cholesterol measurement. The main outcome measure was cholesterol concentration.
Results: A total of 401,489 cholesterol measurements were made on 128,240 patients over the study period. Measurements were categorized as treated and untreated according to whether patients were exposed to lipid-lowering treatment at the time the total cholesterol concentration was measured. Those categorized as untreated fell by 0.86 mmol l(-1) (13.9%) and those categorized as treated by 1.45 mmol l(-1) (23.5%). The difference between baseline and follow-up cholesterol concentrations in intention-to-treat patients was 1.53 mmol l(-1) (24%) in 2002. In the same year, mean cholesterol concentration was 4.71 mmol l(-1) (a fall of 1.65 mmol l(-1) or 25.9%) in patients judged to be taking their lipid-lowering medication, compared with 5.20 mmol l(-1) (a fall of 1.16 mmol l(-1) or 18.2%) in those judged not to be taking treatment. Cholesterol fell by 0.38 mmol l(-1) (6.3%) in a cohort of never treated patients (n = 33,679) between 1993 and 2002.
Conclusions: The impact of lipid-lowering drugs on population cholesterol concentrations in the setting of normal care was significant and comparable with the cholesterol reductions seen in the setting of major statin trials, despite a significant proportion of the population receiving low dose treatment. In those subjects judged to be taking their medication, the benefits achieved were substantial. The impact of nondrug factors is indicated by the fall in population cholesterol seen in the absence of lipid-lowering treatment.