Measuring mortality risk over time for ex-smokers

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Patients who quit smoking cut their risks of heart, cancer and lung death over time.

A new study aimed to measure the decrease in cause-specific mortality among former smokers, based on years since quitting.

Examining data from 438,015 American adults, researchers Blake Thomson, DPhil, and Farhad Islami, MD, PhD, analyzed characteristics 11,860 cardiovascular deaths, 10,935 cancer deaths, and 2,060 respiratory deaths over 5 million per-years of follow-up.

Within 10 years of quitting, ex-smokers avoided an estimated 64% of cardiovascular mortality, 53% of cancer mortality, and 57% of respiratory mortality associated with current smoking, said the research letter, “Association of Smoking Cessation and Cardiovascular, Cancer, and Respiratory Mortality,” published in JAMA Internal Medicine.

More time off tobacco led to more health benefits.

“After 30 or more years of smoking cessation … former smokers avoided an estimated 100%, 93%, and 97% of the excess cardiovascular, cancer, and respiratory mortality associated with continued smoking, respectively,” the study said.

Once smokers stop, the researchers noted there is conflicting evidence about whether increased risk to heart health decreases over 10 to 20 years, or decades later. Cardiovascular disease risk may remain elevated approximately 20 years after quitting, according to previous studies.

Even so, “the hazards of smoking and benefits of quitting may be underestimated,” and over time, ex-smokers may have started again, while some current smokers quit, the study said.

“These findings emphasize that with sustained cessation, cause-specific mortality rates among former smokers may eventually approximate those of never smokers,” the study said.

The data came from the National Health Interview Survey from 1997 followed up through the end of 2019, via linkage to the National Death Index.