April 16 (UPI) -- A well-known drug used to fight cholesterol may not be working as well as it should, new research shows.
After two years of treatment with statins, about half of patients in primary care still didn't hit healthy cholesterol levels, according to a study published Monday in the journal Heart.
"Currently, there is no management strategy in clinical practice which takes into account patient variations in [low-density cholesterol] response, and no guidelines for predictive screening before commencement of statin therapy," the researchers wrote.
The researchers reviewed data collected between 1990 and 2016 for more than 165,000 patients who weren't treated for heart disease or a stroke. These people had their cholesterol measured at least once a year.
The good news for statin users was that every 1 millimole per liter decrease in LDL, or bad cholesterol, was linked to a 6 percent drop in stroke risk.
After two years, if a patient's LDL, or bad cholesterol, didn't fall by at least 40 percent, their statin treatment was considered ineffective.
Overall, people who hit the 40 percent mark had a 14 percent lower risk of cardiovascular disease.
Through the length of the study, nearly 14 percent of patients were diagnosed with heart disease, according to the researchers. Within that group, about 12,000 people missed the 40 percent mark for LDL reduction.
While this study didn't look into why statins weren't effective in lowering cholesterol, one researcher thinks it might be because doctors were afraid to prescribe drugs with a higher dosage.
"Effective implementation of guidelines among healthcare practitioners and the general population has been a challenge for a long time," Marcio Bittencourt, a researcher at University Hospital Sao Paolo and author of an accompanying editorial, said in a news release. "Both physicians and patients should be targets for approaches aiming at improving adherence to guidelines."