Background Dyslipidaemia is a major risk factor for cardiovascular disease (CVD). It is assumed that recent improvements in lipid-lowering treatment- and control-rates would have translated into reductions in mortality among people with dyslipidaemia. Our analysis examined trends in all-cause and CVD mortality among persons with and without dyslipidaemia in three prospective cohorts taken from the 1998, 2003, and 2006 Health Survey for England.
Methods The analytic sample comprised 15,533 people aged 35–84 living in private households with cholesterol measurements, and self-reported medication use, with linkage to NHS mortality data up to March 2013. Dyslipidaemia was defined as a total/HDL cholesterol ratio ≥5 mmol/l or use of lipid-lowering medicines. Analyses were sex-specific. Direct age-standardised mortality rates per 1000 person-years were calculated by HSE cohort. Cox proportional hazards on data pooled across the three cohorts was used to estimate hazard ratios (HRs) and their 95% confidence intervals (CIs) to examine mortality differences by dyslipidaemia status, and whether any such differences in risk differed by HSE cohort.
Results Dyslipidaemia was higher for men than for women in each cohort but prevalence remained unchanged, reflecting the mixture of falling average levels of total/HDL cholesterol ratios and a sharp increase in use of lipid-lowering medicines. Overall, 2004 deaths occurred during a mean follow-up of 10.3 years (SD 3.6), of which 677 were CVD. All-cause mortality rates fell significantly during this period (P < 0.01) for both sexes (men: 21.9 [95% CI: 20.2–23.6] and 11.3 [9.3–13.3] per 1000 person-years in the 1998 and 2006 cohorts respectively; women: 18.7 [17.2–20.2] and 7.8 [6.2–9.4]). CVD mortality also declined (men: 8.4 [7.4–9.5] and 3.7 [2.6–4.9] per 1000 person-years; women: 6.7 [5.8–7.7] and 2.3 [1.4–3.3]).
People with dyslipidaemia had slightly increased risk of all-cause mortality (men: HR = 1.06, 95% CI: 0.92–1.22; women: HR = 1.14, 95% CI: 0.99–1.33). HRs for CVD showed a stronger association with dyslipidaemia (men: HR = 1.37, 95% CI: 1.10–1.71; women: HR = 1.26, 95% CI: 0.97–1.64). Rates of decline in the age-standardised all-cause and CVD mortality rates were comparable in people with and without dyslipidaemia (P > 0.05 for interaction between dyslipidaemia status and HSE cohort). Sensitivity analyses focusing on five-year mortality showed similar associations with dyslipidaemia.
Conclusion Cancer recently replaced CVD as the leading cause of death in the UK, reflecting in part the substantial falls in CVD mortality for both low- and high-risk groups confirmed by this study. Detailed monitoring of trends in mortality rates across groups stratified by preventable risk factors measured using consistent protocols remains vitally important.
- dyslipidaemia cardiovascular-disease mortality
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