OBJECTIVES : Although statins are medicines that must be taken for a long time to prevent cardiovascular diseases (CVD), medication adherence is low. This study aims to understand the importance of medication adherence of statin by analyzing the medication adherence according to the three types of statin(atorvastatin, rosuvastatin, and simvastatin) in Korea and presenting a change in low-density lipoprotein cholesterol(LDL-C) level.

METHODS : We used data from the Korean National Health Insurance Service – Senior(NHIS-senior) cohort. Approximately 550,000 Koreans aged 60 years and older were randomly selected, which accounted for 10% from a total of 5.5 million senior population that were eligible in 2002. We included new users of the moderate-intensity statins in 2010-2014, only those who had been taking for more than one year. We estimated the medication possession ratio(MPR) ranges(high≥80%; 50%≤middle<80%; low<50%) by each kind of statin and changes in LDL-C levels between before and after taking statins according to MPR. A 2-tailed Student’s t-test was used to compare the changes in LDL-C levels and a p-value of less than 0.01 was considered significant.

RESULTS : A total of 3,260 senior patients were included in study population. The patients were treated with moderate-intensity statin therapy including 10-20mg of atorvastatin(n=2,753) or 5-10mg of rosuvastatin(n=240) or 20-40mg of simvastatin(n=267) per day. More than 60% of the patients were represented in high adherence(n=1,994; middle-range=586; low-range=680). The patients in high-range MPR group had the largest change in LDL-C levels(-56.1, from 143.6 to 87.5), followed by middle-range group(-43.8, from 151.6 to 107.8) and low-range group(-16.7, from 152.6 to 135.9). The amounts of change are significantly different for all groups(p<0.0001).

CONCLUSIONS : In elderly patients, statin new users with higher adherence had a greater reduction of LDL-C. Our study results provided real-world evidence that increasing adherence to statin therapy can be helpful in decreasing LDL-C levels.