The timing of lipid-lowering therapy initiation in primary prevention remains debated, particularly among individuals at relatively low cardiovascular risk where absolute event reductions may appear modest. Investigators conducted a systematic review and meta-analysis evaluating the relationship between LDL cholesterol (LDL-C) reduction and major cardiovascular outcomes across lower-risk primary prevention populations. The findings were published in the American Journal of Preventive Cardiology.
Researchers searched EMBASE, MEDLINE, and CENTRAL for randomized placebo-controlled lipid-lowering trials conducted in populations with no or low prevalence of established atherosclerotic cardiovascular disease. Meta-regression analyses examined how baseline event rates influenced the relative risk reduction achieved per 1 mmol/L LDL-C lowering.
Findings
- A total of 17 trials involving 105,879 participants and 6,076 major cardiovascular events were included.
- The analysis included 17 randomized trials comprising 105,879 participants and 6,076 major adverse cardiovascular events in predominantly primary prevention populations.
- Relative risk reduction (RRR) per 1 mmol/L LDL-C reduction declined significantly as baseline cardiovascular risk increased (p<0.0001).
- At a placebo event rate of 1% per year, each 1 mmol/L LDL-C reduction was associated with a 36% reduction in 3P-MACE.
- At a higher event rate of 3% per year, the corresponding relative risk reduction fell to 13%, indicating attenuation of benefit with increasing baseline risk.
- To achieve a 25% relative reduction in major cardiovascular events, the required absolute LDL-C reduction increased from 0.36 mmol/L at a 1% annual event risk to 3.09 mmol/L at a 3% annual event risk (p=0.0001).
Investigators concluded that lower-risk primary prevention populations derive proportionally greater cardiovascular benefit from each unit of LDL-C reduction than higher-risk populations. Conversely, individuals at higher baseline risk may require substantially larger absolute reductions in LDL-C to achieve comparable relative treatment effects.
