Low adherence to cholesterol-lowering drugs also has beneficial effect in patients with type 2 diabetes

Type 2 diabetes patients' risk of cardiovascular disease and death decreases if they actually take the cholesterol-lowering drugs as prescribed. However, research shows that the risk is also reduced if they do not take the full dosage.

"These results are important and useful for patients and healthcare providers alike, to try and motivate patients to follow the recommended treatment even if they forget to take their pills from time to time," notes Sofia Karlsson, Postdoctoral Researcher in Pharmacy at Sahlgrenska Academy, University of Gothenburg.

The purpose of her thesis was to investigate the risk of cardiovascular disease and death in relation to prescription and use of cholesterol-lowering drugs among adults with type 2 diabetes.

The research builds on register-based studies of adults with type 2 diabetes included in the Swedish National Diabetes Register. Prescription of cholesterol-lowering drugs for these patients was estimated from data entered in the Register. The patients' adherence to medications was estimated on the basis of information of filled prescriptions at pharmacies.

One in four stopped to collect

The results show that, on average, patients had cholesterol-lowering drugs available for some 70 percent of the three-year study period. The prescription process may partly explain why this proportion was not 100 percent, and the fact is that one in four patients who started to collect the medication stopped filling their prescriptions as early as within the first year.

During the second year, the proportion of patients who stopped filling their prescriptions dropped to 13 percent, and during the third year the number decreased to 5 percent. Patients with previous cardiovascular disease showed slightly higher adherence than those without prior cardiovascular disease.

Karlsson's thesis is based on studies covering some 100,000 patients. It confirms previous research showing that the risk of cardiovascular disease and death for patients with type 2 diabetes who adhere well to their cholesterol-lowering drug prescriptions is lower than for patients with poor adherence.

Fewer doses also beneficial

What is new is that the researchers were able to observe a gradual increasing risk of cardiovascular disease with decreasing adherence, which suggests that patients who take their medication to a lesser extent than the doctor recommended, too, experience a beneficial effect. This applies to patients with and without prior cardiovascular disease alike.

"When we took into account the attending healthcare provider's adherence with guidelines regarding prescription of cholesterol-lowering drugs, our findings showed that in patients with type 2 diabetes, the patients' adherence to drug treatment is what appears to have the greatest impact on their risk for cardiovascular disease and death," Sofia Karlsson says.