Meta-analysis findings demonstrate that statin therapy should be considered in all individuals with diabetes if they are deemed at "sufficiently high" risk for vascular events, conclude the Cholesterol Treatment Trialists' (CTT) Collaborators in The Lancet Jan 2008.
An earlier CTT meta-analysis of 14 randomized trials of statin therapy showed that lowering low-density lipoprotein (LDL) cholesterol by 1 mmol/l reduces the risk of vascular events (myocardial infarction or coronary death, stroke, or coronary revascularization) by around one-fifth in a broad range of high-risk individuals, largely irrespective of baseline lipid levels and conditions, including diabetes.
For the current study, the CTT investigators conducted pre-specified analyses of the same 14 trials to determine whether individuals with diabetes derive the same benefits from statins as those without.
Uncertainties remain over the effects of statins in diabetic individuals on major coronary events, stroke, and the need for revascularization, and whether their benefits are worthwhile in those without a history of occlusive vascular disease, the team explains.
The researchers report that there were 3247 major vascular events over a mean follow-up of 4.3 years among the 18,686 participants who had diabetes.
These participants had a 9% reduction in all-cause mortality per mmol/l decrease in LDL cholesterol (relative risk [RR]=0.91, p=0.02). This reduction was similar in magnitude to the 13% RR reduction per mmol/l decrease in LDL cholesterol RR=0.87, p<0.0001) in the remaining 71,370 patients without diabetes, the researchers say.
The reduction in all-cause mortality reflected significant reductions in vascular mortality (0.87, p=0.008) and death due to coronary heart disease (0.88, p=0.03) per mmol/l reduction in LDL cholesterol in the diabetic individuals, with no significant effect on vascular mortality (RR=0.97).
There was a significant 21% reduction in major vascular events per mmol/l decrease in LDL cholesterol in both participants with and without diabetes.
Statin therapy was also associated with significant reductions in MI or coronary death, coronary revascularization, and stroke among the diabetic participants.
Finally, the proportional risk reductions for major vascular events among diabetic individuals were similar irrespective of history of vascular disease, gender, age, treated hypertension, body mass index, systolic or diastolic blood pressure, smoking history, and renal function.
The authors comment that the consistency of the reduction in major vascular events suggests that the benefit is likely to hold true in other populations with diabetes.
"Consequently, the absolute benefits in any specific population of patients may be best estimated by application of a reduction of about a fifth per mmol/l LDL cholesterol reduction to the relevant age-specific and sex-specific rates for that population," they write.