SEATTLE — Optimally controlling lipid and blood pressure levels can reduce the risk of stroke by up to 65% in patients at high risk, Dr. Pierre Amarenco reported at the annual meeting of the American Academy of Neurology.
The findings are based on a new analysis of data from the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) trial. The results of this trial, as well as the findings of a recent meta-analysis of stroke-prevention trials (Lancet Neurol. 2009;8:453-63), suggest that the risk of stroke falls steadily in direct proportion to declines in the level of low-density lipoprotein cholesterol (LDL-C).
To assess how much improvements in other cardiovascular risk factors add to risk reduction, Dr. Amarenco, a neurologist at the Denis Diderot University in Paris, and his colleagues further analyzed data from SPARCL.
The researchers assessed associations between lipid and blood pressure levels at 1 month after randomization and clinical outcomes after a mean follow-up of 4.9 years.
In SPARCL, 4,732 patients at high risk for stroke because of a previous stroke or transient ischemic attack were randomized in equal numbers to treatment with atorvastatin or placebo.
The trial's main results, previously reported, showed that patients in the atorvastatin group were significantly less likely to experience both stroke and major cardiovascular events. Patients whose reductions in LDL-C level exceeded the median overall reduction (16%) in the trial population were significantly less likely to experience a stroke (hazard ratio, 0.79) or a major cardiovascular event (hazard ratio, 0.76), compared with their counterparts.
The subset analysis by Dr. Amarenco and his associates went beyond these measures. They assessed associations between lipid and blood pressure levels at 1 month after randomization and clinical outcomes after a mean follow-up of 4.9 years.
For patients whose LDL-C reductions were above the median value, their risks of events also were significantly reduced if their levels of high-density lipoprotein cholesterol (HDL-C) exceeded the median value (47 mg/dL) or if their systolic BP levels were below the median value (138 mm Hg).
There also was a trend toward additional reductions in stroke and cardiovascular events for patients whose triglyceride levels were above the median reduction (15%), as well as for those whose diastolic BP was below the median value (80 mm Hg).
A final, exploratory analysis assessed the combined effects of optimal control of four measures, based on targets outlined in national guidelines: an LDL-C level of less than 70 mg/dL, an HDL-C level of more than 50 mg/dL, a triglyceride level of less than 150 mg/dL, and a BP of less than 120/80 mm Hg.
Optimal control was achieved for one measure by 24%, for two measures by 41%, for three by 19%, and for four by 2%.
“There was a dose-response relationship,” Dr. Amarenco observed. The hazard ratios for both stroke and major cardiovascular events decreased significantly as the number of optimally controlled measures increased.
Compared with trial participants who did not achieve optimal control of any measures, patients achieving optimal control of all four measures had a 65% relative reduction in the risk of stroke and a 75% relative reduction in the risk of major cardiovascular events.
Dr. Amarenco reported that he has received honoraria from Pfizer Inc. as a member of the steering committee and speaker fees. The SPARCL trial was sponsored by Pfizer Inc.