Background Serum total cholesterol is one of the major targets for cardiovascular disease prevention. Statins are effective for cholesterol control in individual patients. At the population level, however, their contribution to total cholesterol decline remains unclear. The aim of this study was to quantify the contribution of statins to the observed fall in population mean cholesterol levels in England over the past two decades, and explore any differences between socioeconomic groups.

Methods This is a modelling study based on data from the Health Survey for England (HSE). We analysed changes in observed mean total cholesterol levels in the adult England population (aged 18 and over) between 1991–92 (baseline) and 2011–12. We then compared the observed changes with a counterfactual ‘no statins’ scenario, where the impact of statins on population total cholesterol was estimated and removed. Statin effectiveness in the population was modelled based on published meta-analyses, self-reported statin uptake from HSE and the 2011 and 2012 Prescription Cost Analysis reports. We estimated uncertainty intervals (UI) using Monte Carlo simulation, where confidence intervals (CI) were impractical. The analysis was stratified by age-group, sex and quintiles of index of multiple deprivation (where possible and relevant) and was performed in R v3.1.0 statistical software.

Results In 2011–12, 13.2% (95% CI: 12.5–14.0%) of the English adult population used statins at least once per week, compared with 1991–92 when the proportion was just 0.5% (95% CI: 0.3–1.0%) for any lipid lowering medication. Statin utilisation was higher among the most deprived groups. Between 1991–92 and 2011–12, mean total cholesterol declined from 5.86 mmol/L (95% CI: 5.82–5.90) to 5.17 mmol/L (95% CI: 5.14–5.20). For 2011–12, mean total cholesterol was about 5% lower in most deprived group compared to the most affluent group.

In our ‘no statins’ scenario we predicted a mean total cholesterol of 5.36 mmol/L (95% CI: 5.33–5.40) for 2011–12. Statins were responsible for approximately 33.7% (95% UI: 28.9–38.8%) of the total cholesterol reduction since 1991–92. The statin contribution to cholesterol reduction was greater among the more deprived groups of women, while showing little socio-economic gradient among men.

Conclusion Our model suggests that statins explained around a third of the substantial falls in total cholesterol observed in England since 1991 and their impact on reducing socioeconomic inequalities in total cholesterol was generally positive. Approximately two thirds of the cholesterol decrease can reasonably be attributed to dietary improvements.