Association of Low-Density Lipoprotein Testing After an Atherosclerotic Cardiovascular Event with Subsequent Statin Adherence and Intensification

Purpose: This study aimed to evaluate associations between outpatient low-density lipoprotein cholesterol (LDL-C) testing and subsequent statin adherence and intensification in patients after an atherosclerotic cardiovascular (ASCVD) event.

Methods: This was a longitudinal study of adult members of Kaiser Permanente Northern California hospitalized with an ASCVD event (myocardial infarction or stroke) during January 01, 2016, to December 31, 2017, with follow-up through December 31, 2019. Outcomes were statin adherence (estimated using continuous medication gap [CMG]) and intensification (defined by an increased dose or switch to a higher-intensity statin) based on pharmacy dispensing. The exposure of interest was first outpatient LDL-C test after an ASCVD event. Baseline for follow-up was LDL-C test date or a date assigned using incidence density sampling. Multivariate logistic regression models were specified to estimate the odds ratios for statin adherence or intensification among those with vs without an LDL-C test, with adjustment for age, sex, race/ethnicity, smoking, hypertension, diabetes, body mass index, and estimated glomerular filtration rate.

Results: There were 19,604 adults hospitalized with ASCVD, including 7054 adults not on high-intensity statins. The mean age was 69.5 years and 33.0% were female. Prevalence of good adherence (continuous medication gap ≤20%) was significantly higher (80.2% vs 75.9%; odds ratio 1.38; 95% confidence interval, 1.28-1.49; P <.001) among participants who had an LDL-C test compared with participants who did not. LDL-C testing was associated with significantly higher rates of treatment intensification (16.1% vs 10.7%; odds ratio 1.51; 95% confidence interval,1.29-1.76; P <0.001).

Conclusions: Low-density lipoprotein cholesterol testing is recommended for patients with a history of ASCVD and may be a high-value and low-cost intervention to improve adherence and statin management.