*4.1.5 Hypercholesterolaemia*

Among 11,320 newly diagnosed patients with hypercholesterolemia initiated with statins, late statin initiation increased the risk of CVD events compared with early statin initiation (HR 1.24, 95% CI 1.02–2.51). Among early initiators, statin discontinuation was associated with increased risk for CVD (HR 1.71, 95%CI 1.10–2.67), but statin reinitiation was associated with decreased risk (HR 1.34, 95%CI 0.79–2.30) [46]. Another study in China with 99,655 adult patients indicated a 37% reduced risk of MACEs in those with ≥50% adherence with a statin (aHR0.63, 95% CI, 0.41–0.98). Unlike primary prevention, no relationship between secondary prevention and statin adherence (PDC ≥ 50%) was detected in this study [47]. Previous studies, however, found statin adherence benefits in reducing the risk of adverse health outcomes for secondary prevention [48–51]. These discrepancies might be due to different baseline patient characteristics (CVD and its severity) and PDC cutoff points (50% in the Chinese study vs. 80% in others' studies). Secondary prevention seems to require ≥80% adherence to reduce cardiovascular risk.

In the elderly, a study on 29,047 patients aged ≥65 receiving polypharmacy found that those who discontinued statins while maintaining other medications had an increased risk of hospital admissions for any cardiovascular outcome (HR 1.14, 95% CI 1.03–1.26), HF (HR 1.24, 95% CI, 1.07–1.43), all-cause mortality (HR 1.15, 95% CI 1.02–1.30), and emergency admissions (HR 1.12, 95% CI 1.05–1.19) (all *P* < 0.05) [52]. In diabetic patients aged ≥65 with comorbidities, those adhering optimally to statins (PDC ≥ 80) had a decreased LDLc (<100 mg/dl) across all age groups (e.g., ≥85: RR 1.13, 95% CI 1.09–1.16, *P* < 0.05) and in all comorbid levels (e.g. ≥4: RR 1.13, 95% CI 1.12–1.15, *P* < 0.05) [41]. The LDLc target of <100 mg/dl was associated with a lower risk of adverse cardiac outcomes [53].
