Improved Treatments Lead to Improved CHD Mortality

Although rates of coronary heart disease (CHD) mortality have declined substantially over the last three decades, the exact reasons for this are not yet clear.  Identifying the factors associated with this improvement is vital for setting future healthcare policy.  Diet, lifestyle, risk factors and treatment uptake are all important, but these change rapidly and have not been studied in the last decade.
This prospective Canadian study, which was carried out in Ontario between 1994 and 2005, aimed to determine what proportion of the decline was due to temporal trends in CHD risk factors and improvements in cardiovascular treatments.  An updated version of the validated IMPACT model was used, which takes into account population size, CHD mortality, risk factors and changes in the uptake of treatments.  The primary outcome measure was the number of deaths prevented or delayed in 2005, while secondary outcomes included trends in risk factors and improvements in medical treatments.
Over the ten year period studied, the age-adjusted CHD mortality rate in Ontario decreased by 35% from 191 to 125 deaths per 100,000 inhabitants, meaning an estimated 7585 fewer CHD deaths in 2005.  43% of the total mortality decrease was attributed to improvements in medical and surgical treatments, most noticeably a 17% drop in chronic stable coronary artery disease, a 10% drop in community heart failure, and an 8% drop in acute myocardial infarction.  Trends in risk factors also accounted for 3660 fewer CHD deaths prevented or delayed (48% of the total), largely attributable to reductions in total cholesterol (23%) and systolic blood pressure (20%).

Between 1994 and 2005 a significant decrease in CHD mortality rates was seen in Ontario, largely due to trends in risk factors and improvements in medical treatments, each of which explained about half of the decrease.

•    Wijeysundera HC, Machado M, Farahati F, Wang X, Witteman W, van der Velde G, et al. Association of temporal trends in risk factors and treatment uptake with coronary heart disease mortality, 1994-2005. JAMA 2010, May 12;303(18):1841-7.

Meta-analysis underlines benefits of fibrates

Despite their beneficial effects on the lipid profile, some recent fibrate trials have shown no beneficial effect from their use (e.g. the ACCORD study, see figure).  The aim of this meta-anlysis of clinical trials was to clarify the likely effects of fibrate therapy on major clinical outcomes.
18 randomised controlled trials met the inclusion criteria, including a total of 45, 058 patients.  Fibrate therapy was associated with a 10% relative risk reduction for major cardiovascular events (p=0.048) and a 13% relative risk reduction for coronary events (p<0.0001), however no benefit was noted for stroke (-3%, p=0.69).  However no effect of fibrate therapy was seen on the risk of all-cause mortality (0%, p=0.92), cardiovascular mortality (3%, p=0.59), sudden death (11%, p=0.19), or non-vascular mortality (-10%, p=0.063).  Although increases in serum creatinine concentration were common (1.99, p<0.0001), fibrates reduced the risk of albuminuria progression by 14%.

Fibrates act to reduce the risk of major cardiovascular events largely by preventing coronary events.  The effect may be most beneficial in those at high risk and with high triglycerides.

•    Jun M, Foote C, Lv J, Neal B, Patel A, Nicholls SJ, et al. Effects of fibrates on cardiovascular outcomes: A systematic review and meta-analysis. Lancet 2010, May 10.

Figure 1 The effect of fibrates on major cardiovascular outcomes in the clinical trials analysed
figure 1

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