A study by the University of Liverpool has found that a decrease in smoking rapidly reduces mortality rates in individuals and entire populations within six months.
Research by Professor Simon Capewell and Dr Martin O'Flaherty at the Institute of Psychology, Health and Well-being, examined evidence from clinical trials and natural experiments. They found that a reduction in smoking has a positive impact on mortality rates in both individuals and populations within six months. Likewise, dietary improvements get very positive results within one to three years.
Professor Capewell said:"Our research found that smoking bans and diet improvements powerfully and rapidly reduce chronic disease in both individuals and in the wider population. This actually happens quickly, within a far shorter timescale than had previously been assumed; within months and years rather than decades. This discovery means that policies such as smoking bans or reducing saturated fats are effective at improving health and would save the NHS millions very rapidly."
The study found that policies that reduce smoking consistently have a rapidly positive effect on mortality rates and hospital admissions in countries and communities around the world. After smoke-free legislation was introduced in Scotland in 2006, hospital admissions for acute coronary syndrome decreased by 17% with a 6% decrease in out-of-hospital cardiac deaths.
Similarly, when smoke-free legislation was introduced in Helena, an isolated community in the US, it resulted in a 40% drop in admission rates for acute coronary syndrome within six months in one hospital. When the law was repealed the coronary admissions returned to previous levels within six months.
Changes to diet also have a rapid and positive impact on the reduction of mortality rates for coronary heart disease. Coronary death rates rose steadily during the 20th Century, peaking in the 1970s in the UK, US and Western Europe. However, closer scrutiny of national trends revealed a notch in the early 1940s. This has been attributed to sudden decreases in dietary meat and animal fats due to food rationing during the Second World War.
More recently, a study of coronary disease in Poland found that death rates from heart disease had been rising steadily. From 1990, however, they quickly dropped by 25% after meat and animal fat subsidies from the communist countries ceased and cheap vegetable oils and fruit flooded the market. A study of other central European countries confirmed very similar trends.
The research was published in The Lancet.
- Simon Capewell, Martin O'Flaherty. Rapid mortality falls after risk-factor changes in populations. The Lancet, 2011; 378 (9793): 752 DOI: 10.1016/S0140-6736(10)62302-1
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