New research suggests that during the first several years of cholesterol-lowering statin treatment, random fluctuations in total and “bad” LDL cholesterol are common and that true, long-term changes achieved with statin therapy occur relatively slowly.

Therefore, “current guidelines that recommend annual or more frequent monitoring should be reconsidered,” conclude Dr. Paul P. Glasziou from the University of Oxford, UK and colleagues in a report in the May 6th issue of the Annals of Internal Medicine.

After the initial decrease in cholesterol in response to statin treatment, retesting every 3 to 5 years may be sufficient, they write.

“We probably monitor cholesterol too often,” Glasziou noted in comments to Reuters Health. “Most of the apparent change is just measurement error and true change is much slower than we expect.”

Glasziou and colleagues analyzed cholesterol measurement data from 9,014 participants in a long-term statin trial. Participants had their cholesterol levels measured at the start of treatment with a statin (pravastatin) or placebo and again at 6 and 12 months and then annually to 5 years.

Results showed that during the first 4 years of statin therapy, the random fluctuation in cholesterol levels was greater than the long-term effect of the drug. According to the researchers, it takes “approximately 3 years before plausible changes in true cholesterol values could be comparable with the short-term variation.”

The results of this study suggest that frequent testing of cholesterol levels while on statin treatment will often be misleading, the investigators warn.

SOURCE: Annals of Internal Medicine, May 6, 2008.