Effects on 11-year mortality and morbidity of lowering LDL cholesterol with simvastatin for about 5 years in 20,536 high-risk individuals: a randomised controlled trial

Background: Findings of large randomised trials have shown that lowering LDL cholesterol with statins reduces vascular morbidity and mortality rapidly, but limited evidence exists about the long-term efficacy and safety of statin treatment. The aim of the extended follow-up of the Heart Protection Study (HPS) is to assess long-term efficacy and safety of lowering LDL cholesterol with statins, and here we report cause-specific mortality and major morbidity in the in-trial and post-trial periods.

Methods: 20,536 patients at high risk of vascular and non-vascular outcomes were allocated either 40 mg simvastatin daily or placebo, using minimised randomisation. Mean in-trial follow-up was 5·3 years (SD 1·2), and post-trial follow-up of surviving patients yielded a mean total duration of 11·0 years (SD 0·6). The primary outcome of the long-term follow-up of HPS was first post-randomisation major vascular event, and analysis was by intention to treat. This trial is registered with ISRCTN, number 48489393.

Findings: During the in-trial period, allocation to simvastatin yielded an average reduction in LDL cholesterol of 1·0 mmol/L and a proportional decrease in major vascular events of 23% (95% CI 19-28; p<0·0001), with significant divergence each year after the first. During the post-trial period (when statin use and lipid concentrations were similar in both groups), no further significant reductions were noted in either major vascular events (risk ratio [RR] 0·95 [0·89-1·02]) or vascular mortality (0·98 [0·90-1·07]). During the combined in-trial and post-trial periods, no significant differences were recorded in cancer incidence at all sites (0·98 [0·92-1·05]) or any particular site, or in mortality attributed to cancer (1·01 [0·92-1·11]) or to non-vascular causes (0·96 [0·89-1·03]).

Interpretation: More prolonged LDL-lowering statin treatment produces larger absolute reductions in vascular events. Moreover, even after study treatment stopped in HPS, benefits persisted for at least 5 years without any evidence of emerging hazards. These findings provide further support for the prompt initiation and long-term continuation of statin treatment.

Funding: UK Medical Research Council, British Heart Foundation, Merck & Co, Roche Vitamins.