Benefits and Risks Associated With Statin Therapy for Primary Prevention in Old and Very Old Adults

BACKGROUND: There is little consensus on using statins for primary prevention of cardiovascular diseases (CVDs) and all-cause mortality in adults aged 75 years or older due to the underrepresentation of this population in randomized controlled trials. OBJECTIVE: To investigate the benefits and risks of using statins for primary prevention in old (aged 75 to 84 years) and very old (aged ≥85 years) adults. DESIGN: Sequential target trial emulation comparing matched cohorts initiating versus not initiating statin therapy. SETTING: Territory-wide public electronic medical records in Hong Kong. PARTICIPANTS: Persons aged 75 years or older who met indications for statin initiation from January 2008 to December 2015 were included. Participants with preexisting diagnosed CVDs at baseline, such as coronary heart disease (CHD), were excluded from the analysis. Among 69 981 eligible persons aged 75 to 84 years and 14 555 persons aged 85 years or older, 41 884 and 9457 had history of CHD equivalents (for example, diabetes) in the respective age groups. INTERVENTION: Initiation of statin therapy. MEASUREMENTS: Incidence of major CVDs (stroke, myocardial infarction, or heart failure), all-cause mortality, and major adverse events (myopathies and liver dysfunction). RESULTS: Of 42 680 matched person-trials aged 75 to 84 years and 5390 matched person-trials aged 85 years or older (average follow-up, 5.3 years), 9676 and 1600 of them developed CVDs in each age group, respectively. Risk reduction for overall CVD incidence was found for initiating statin therapy in adults aged 75 to 84 years (5-year standardized risk reduction, 1.20% [95% CI, 0.57% to 1.82%] in the intention-to-treat [ITT] analysis; 5.00% [CI, 1.11% to 8.89%] in the per protocol [PP] analysis) and in those aged 85 years or older (ITT: 4.44% [CI, 1.40% to 7.48%]; PP: 12.50% [CI, 4.33% to 20.66%]). No significantly increased risks for myopathies and liver dysfunction were found in both age groups. LIMITATION: Unmeasured confounders, such as lifestyle factors of diet and physical activity, may exist. CONCLUSION: Reduction for CVDs after statin therapy were seen in patients aged 75 years or older without increasing risks for severe adverse effects. Of note, the benefits and safety of statin therapy were consistently found in adults aged 85 years or older. PRIMARY FUNDING SOURCE: Health Bureau, the Government of Hong Kong Special Administrative Region, China, and National Natural Science Foundation of China.