Smoking Increase Death Risks

Vascular Benefits of Stopping Smoking Are Rapid

News Author: Lisa Nainggolan Medscape
CME Author: Charles Vega, MD

Smoking is clearly linked with an increased risk of mortality, and a previous report on the Nurses' Health Study by Kawachi and colleagues, published in the November 15, 1993, issue of Annals of Internal Medicine, described this risk in detail. Researchers demonstrated that the overall risk of mortality among smokers vs never smokers was 1.87, and the risk of former smokers vs never smokers was significantly elevated at 1.29. Participants who initiated smoking before the age of 15 years had the highest risks for total mortality and cardiovascular disease mortality, but these risks were attenuated to levels similar to never smokers after 10 to 14 years of abstinence from smoking.

The current report from the Nurses' Health Study provides greater detail with regard to cancer mortality risks associated with cigarette smoking in women.

Study Highlights

• The Nurses' Health Study began following 121,700 female nurses in the United States in 1976. Subjects have provided health information every 2 years since initiation of the study, including data regarding cigarette use. Women with a prior history of cancer were excluded from the current study.
• In the current study, researchers focused on reports of overall mortality as well as specific cancer, vascular, and respiratory causes of mortality from 1980 forward. Never smokers were used as the reference group, and the risk of study outcomes associated with smoking was adjusted for body mass index as well as disease and lifestyle factors.
• In 1980, 28% of the study cohort reported current smoking, and 26% were former smokers. The mean age at smoking initiation was 19 years.
• Current smokers had lower body mass index values and slightly less hypertension and also exercised less compared with never or former smokers.
• 12,483 deaths occurred in the study group, 28.9% and 35.2% of which occurred among current and former smokers, respectively. Only 8% of subjects alive in 2002 were current smokers.
• Current smokers experienced a HR of 2.81 for total mortality compared with never smokers, and they were also at higher risk for all major cause-specific mortality.
• Current smokers had a higher risk of death associated with all smoking-related cancers vs never smokers. These cancer sites included bladder, cervix, esophagus, lip and mouth, pharynx, pancreas, and stomach. Smokers were also at higher risk of mortality resulting from acute myeloid leukemia.
• Current smokers also had a significant increased risk of mortality resulting from colorectal cancer vs never smokers (HR = 1.63), but the effect of current smoking on the risk of ovarian cancer mortality was not significant. These same trends were evident among former smokers.
• Overall, 64% of deaths among current smokers were attributable to cigarette smoking.
• Earlier initiation of smoking was associated with a higher risk of death, particularly for death related to respiratory disease or cancer.
• The risk of death decreased by 13% within 5 years of quitting cigarettes, and this risk was further attenuated to levels comparable with never smokers at 20 years after quitting.
• The risk of death resulting from vascular disease declined more rapidly compared with other mortality risks following smoking cessation, with 61% of the full potential benefit for coronary heart disease mortality accrued in the first 5 years after quitting.
• Approximately 28% of deaths among former smokers were attributable to cigarette smoking.

Pearls for Practice

• A previous report from the Nurses' Health Study demonstrated that both current and former smokers had an increased risk of mortality compared with never smokers, but this risk was significantly attenuated after 10 to 14 years of abstinence from smoking. Women who began smoking prior to 15 years of age experienced the highest risk of mortality.
• In the current study, smoking increased the risk of death due to cancers of the cervix, colon and rectum, and stomach. However, the risk of ovarian cancer mortality was not significantly increased with smoking.