MedWire News: Women who quit smoking are around 60% less likely to die from coronary heart disease, and significantly less likely to die of any cause, within 5 years of kicking the habit than those who continue to smoke, study results show.

"Tobacco use remains the leading preventable cause of death in the USA. Globally, approximately 5 million premature deaths were attributable to smoking in 2000. The World Health Organization projects by 2030 that tobacco-attributable deaths will annually account for 3 million deaths in industrialized countries and 7 million in developing countries," explain Stacey Kenfield, from Harvard School of Public Health in Boston, Massachusetts, and team.

They add that quitting smoking can significantly reduce the risk of death from associated conditions, but the timescale of this reduction in risk after quitting had been uncertain.

The team studied data on more than 104,000 women who participated in a long-term health study between 1980 and 2004.

In total, 12,483 women died during the study period, including 4485 women who had never smoked, 3602 who were current smokers at the time of their death and 4396 who were past smokers.

Analysis revealed that, overall, women who quit smoking were 13% less likely to die from any cause 5 years after kicking the habit than those who continued to smoke, and that this risk fell to the same level as someone who had never smoked after 20 years.

Regarding the risk of death from specific smoking-related diseases, women who quit smoking were 61% less likely to die from coronary heart disease and 42% less likely to die of a stroke 5 years after kicking the habit than women who continued to smoke.

For death due to respiratory diseases such as chronic obstructive pulmonary disease, an 18% reduction was observed 5 to 10 years after quitting smoking, with the risk reaching that of a never smoker's after 20 years.

The risk of lung cancer also fell by 21% within 5 years of quitting smoking, but did not fall to the same level as someone who had never smoked until 30 years after quitting.

"Most of the excess risk of [cardiovascular] mortality due to smoking in women may be eliminated rapidly upon cessation and within 20 years for lung diseases," the researchers write in the Journal of the American Medical Association.

However, they add: "Early age at initiation is associated with an increased mortality risk so implementing and maintaining school tobacco prevention programmes, in addition to enforcing youth access laws, are key preventive strategies.

"Effectively communicating risks to smokers and helping them quit successfully should be an integral part of public health programs."