About half of the statin patients do not see a drop in cholesterol to desirable levels within two years, according to a new study.
Guidelines from the National Institutes of Health and Excellence aim to reduce 40% or more of low-density lipoprotein cholesterol consumption from treatment.
However, a new study, published in the journal Heart, found that half of the people (51 percent) received a "suboptimal" response after 24 months on the drugs.
The researchers, from the University of Nottingham, analyzed data from 165,411 patients receiving statins prescribed for primary care between 1990 and 2016.
They were on average 62 years when they started treatment.
A total of 84,609 patients received a "sub-optimal" response after 2 years and did not have a 40% or more cholesterol reduction.
The authors note that a higher rate of patients with "sub-optimal" response had lower doses than those with "optimal" response.
Patients who did not reach the targeted levels were 22% more likely to develop cardiovascular disease than those who responded well.
According to the researchers, the study provides "real-world evidence" about statins.
"These findings contribute to the debate on the efficacy of statin therapy and emphasize the need for personalized medicine for lipid management in patients," the authors write.
Professor Metin Avkiran, senior medical director at the British Heart Foundation, said: "Statins are an important and proven treatment for lowering cholesterol and reducing the risk of a fatal heart attack or stroke.
Although this study suggests that not everyone who is prescribed statins manages to reduce their cholesterol enough, it does not explain why.
"It is possible that these people were prescribed low-dose or low-intensity statins because they did not take the drug as prescribed, or because they did not respond well to the type of statins that they were prescribed.
"If you have been prescribed statins you should continue to take them regularly, as prescribed.
"If you have concerns you should talk about your medicine with GP.
Professor Helen Stokes-Lampard, chairman of the Royal College of Physicians, said: "When we prescribe drugs, we have to rely on patients to make sure they take it, both at the recommended dose and for the time we think they will enjoy most.
"There is a significant body of research showing that statins are safe and effective drugs for most people and can reduce the risk of heart attacks and strokes when properly determined – but controversy remains around their widespread use and possible side effects.
"There are complex reasons why patients choose not to take their prescription drugs, and mixed messages around statins can be one of those."