Smoking cessation significantly reduces excess mortality within a decade

Key takeaways:

• Former smokers had little to no excess cardiovascular mortality 20 to 29 years after quitting.
• Sustained cessation may help former smokers reach cause-specific mortality rates similar to those who never smoked.

A recent study showed that excess cardiovascular and respiratory mortality among former smokers was less than half of that among continuing smokers within the first decade of smoking cessation.

Blake Thomson, DPhil, a medical student from the University of Stanford, told Healio the findings were surprising “in that the excess mortality avoided is generally similar across cardiovascular, cancer and respiratory causes of death.”

Thomson and Farhad Islami, MD, PhD, an adjunct associate professor at Emory University’s Rollins School of Public Health, noted that smoking cessation is linked to significant reductions in excess mortality, “but the timescale over which cause-specific mortality benefits of cessation may develop is unclear.”

“Quantifying excess cause-specific mortality among former smokers by years since quitting may inform clinical decision-making and screening programs,” they wrote in JAMA Internal Medicine.

The researchers evaluated data on 438,015 adults who participated in the National Health Interview Survey from 1997 to 2018 to determine associations between smoking cessation and changes in excess cause-specific mortality. The participants had a mean age of 47 years and 56% were women.

There were 11,860 cardiovascular deaths, 10,935 cancer deaths and 2,060 respiratory deaths over 5 million person-years of follow-up.

Overall, the mortality RRs for current vs. never smokers were:

• 2.3 (95% CI, 2.17-2.44) for cardiovascular mortality;
• 3.38 (95% CI, 3.19-3.58) for cancer mortality; and
• 13.31 (95% CI, 11.46-15.45) for respiratory mortality.

Within the first decade after quitting smoking, Thomson and Islami wrote that former smokers “avoided an estimated 64%, 53%, and 57% of excess cardiovascular, cancer, and respiratory mortality associated with current smoking, respectively, with further health benefits accruing over time.”

Former smokers had little or no excess cardiovascular mortality 20 to 29 years after quitting (RR = 1.07; 95% CI, 0.97-1.18), and avoided an estimated 100%, 97% and 93% of excess cardiovascular, respiratory and cancer mortality linked to current smoking, respectively, after 30 years of smoking cessation.

“Moderate excess cancer and respiratory mortality was observed even 30 years or more after quitting, which nevertheless reflects a more than 90% relative reduction in excess mortality compared with continued smoking,” Thomson and Islami wrote.

Thomson emphasized that primary care physicians should “communicate to patients that quitting smoking really works, and that the body can heal itself in remarkable ways.”

“It is never too early to quit, but it's also never too late,” he said. “Today is the day, whatever your age, to quit smoking ... and to commit to continuing to try if unsuccessful at first. Quitting smoking is the greatest investment smokers can make in their health.”

Thomson added that PCPs should also understand that smoking cessation does not reverse damage done by smoking immediately “but rather over time.”

“Individuals who recently quit are still at excess risk of cardiovascular disease, cancer and respiratory disease as compared to those who have never smoked, and their care should reflect this,” he said. “Screening, risk prediction equations and clinical management should recognize this.”