(CNN) Half of all people who are prescribed statins for the prevention of heart disease fail to reach target cholesterol levels two years later, according to a new study.

Researchers used data submitted to the UK Clinical Practice Research Datalink by 681 family doctors. The study group was made up of 165,411 people who were prescribed a statin between 1990 and 2016 and who had not been treated for heart disease or stroke before the prescription.

They defined an "appropriate" response to statin therapy as a reduction of 40% or more in LDL or "bad" cholesterol, as recommended by the UK's National Institute for Health and Care Excellence.

Fewer than half of all people enrolled over the 26-year study period -- 48.8% -- achieved target cholesterol levels at the two-year followup mark, with just over half -- 51.2% -- falling short, according to the study, published Monday in the journal Heart

After taking into account differences in age and underlying medical conditions, the researchers found that people who did not lower their LDL cholesterol enough were 22% more likely to develop cardiovascular disease than those who did lower it.