Routine LDL Exam For Cancer Survivors

Overview

This observational study will evaluate whether annual low-density lipoprotein cholesterol (LDL-C) testing is associated with improved cardiovascular preventive care and a lower risk of cardiovascular events among cancer survivors. The study will use nationwide health insurance and cancer registry data from Korea. Adults with a history of cancer who are alive at least 1 year after cancer diagnosis, have no prior major cardiovascular disease, and are not receiving statin therapy at the start of an eligible study period will be included. The investigators will compare cancer survivors who undergo LDL-C testing with similar cancer survivors who do not undergo LDL-C testing. Participants will not be assigned to receive testing or treatment by the investigators. Instead, routinely collected health care data will be analyzed. The main outcome will be major adverse cardiovascular and cerebrovascular events, including cardiovascular death, myocardial infarction, stroke, and coronary revascularization. The study will also examine whether LDL-C testing is associated with subsequent initiation of statin therapy. The findings may help determine whether routine lipid testing can support cardiovascular disease prevention as part of long-term survivorship care for people with cancer.

Cardiovascular disease is an important cause of long-term morbidity and mortality among cancer survivors. Current cardio-oncology and survivorship guidelines recommend periodic assessment of cardiovascular risk factors, including lipid profiles. However, limited evidence is available regarding whether routine LDL-C testing leads to greater initiation of preventive therapy or fewer cardiovascular events in cancer survivors. This nationwide observational cohort study will evaluate the association between annual LDL-C testing and cardiovascular outcomes among statin-naive cancer survivors. The study will use routinely collected administrative health insurance and cancer registry data from Korea. A sequential target trial emulation design will be used. Eligibility will be reassessed at a series of annual trial baselines beginning 1 year after cancer diagnosis. At each trial baseline, individuals will be eligible if they are alive, remain under observation, have no history of cardiovascular disease, myocardial infarction, stroke, familial hypercholesterolemia, percutaneous coronary intervention, or coronary artery bypass grafting, and are not receiving statin therapy. The same individual may contribute to more than one annual emulated trial if all eligibility criteria continue to be met. At each eligible trial baseline, participants will be classified according to whether they undergo LDL-C testing. Participants in the active testing group will be compared with participants in the inactive testing group. Propensity scores will be estimated using demographic and clinical variables, including age, sex, cancer type, cancer diagnosis year, cancer stage, hypertension, diabetes mellitus, and dyslipidemia. One-to-one propensity score matching will be performed within each emulated trial. The primary outcome will be major adverse cardiovascular and cerebrovascular events, defined as a composite of cardiovascular death, myocardial infarction, stroke, and coronary revascularization. Secondary outcomes will include the individual components of the composite outcome and initiation of statin therapy within 1 year after the trial baseline. For the analysis of statin initiation, participants will be followed for up to 1 year. Follow-up will end at statin initiation, a major cardiovascular event, censoring, or the end of the observation period. For cardiovascular outcome analyses, follow-up will begin at the corresponding annual trial baseline. Participants in the inactive testing group who subsequently undergo LDL-C testing will be censored at the date of testing. Inverse probability-of-censoring weighting will be used in sensitivity analyses to address potential informative censoring. Hazard ratios and 95% confidence intervals will be estimated using Cox proportional hazards models. Because individuals may contribute to multiple annual emulated trials, robust sandwich variance estimators clustered at the participant level will be used to account for within-person correlation. Competing-risk analyses will account for non-cardiovascular death when evaluating nonfatal cardiovascular outcomes. Exploratory analyses will evaluate cardiovascular outcomes according to subsequent statin initiation after LDL-C testing. These analyses will be interpreted cautiously because statin use is determined after the trial baseline and is not a randomized treatment assignment. Prespecified subgroup analyses will be conducted according to sex, age, cancer stage, time since cancer diagnosis, cancer type, and diabetes status. This study is observational. The investigators will not assign LDL-C testing, statin therapy, or any other clinical intervention.