Serum Lipoprotein(a) Levels and Their Association with Atherosclerotic Cardiovascular Disease in Japan

Aims: To investigate the distribution of lipoprotein(a) (Lp(a)) and its association with atherosclerotic cardiovascular disease (ASCVD) in Japanese patients at high risk for ASCVD using a health insurance database. Methods: Between July 2013 and June 2021, patients eligible for ASCVD prevention according to the 2017 Japan Atherosclerosis Society (JAS) guidelines with documented Lp(a) test results were extracted from the Medical Data Vision claims database and divided into three groups: primary prevention high-risk (Group I), secondary prevention (Group II) and secondary prevention high-risk (Group III). Data on lipid levels, cardiovascular morbidity risk factors and lipid-lowering treatments were extracted. Results: Of 700,580 patients with documented low-density lipoprotein cholesterol (LDL-C), 2,967 (0.42%) were tested for Lp(a). In 2,170 eligible patients, the median [interquartile range] serum concentration of Lp(a) was 13.9 [7.5-24.6] mg/dL, with 151 patients (7.0%) above the recommended risk threshold of >= 50 mg/dL. Lp(a) levels increased with risk across all prevention groups. Being in the highest Lp(a) quintile (Q5) was associated with an increased frequency of ASCVD (28.9% versus 18.9% in the lowest quintile (Q1) for unstable angina; 18.7% versus 10.1% for myocardial infarction; 27.9% versus 17.0% for ischemic stroke). In the secondary prevention groups, the proportion of patients meeting an LDL-C target of <70 mg/dL decreased from 30.2% in Q1 to 19.0% in Q5 for Group II and from 32.9% to 16.3% for Group III. Conclusions: Despite a high prevalence of Lp(a) >= 50mg/dL in Japanese patients at high risk for ASCVD, it found that the Lp(a) testing rate was very low.