A new study published in the American Journal of Preventive Medicine, found that people aged 70 or older currently smoking were more than three times more likely to die than never-smokers, while former smokers were less likely to die the sooner they quit.
In the U.S., the number of individuals aged 70 years and older is expected to increase from 29.2 million (9.3 percent of the population) in 2012, to 63.6 million individuals (15.9percent) in 2050.
“U.S. adults aged 70 and older have a very high lifetime prevalence of cigarette smoking, so it’s important to examine the risks associated with smoking and the benefits of quitting at older ages among these individuals,” explained lead investigator Sarah H. Nash, PhD, who conducted the research as part of her postdoctoral training at the National Cancer Institute, NIH, Bethesda, MD.
Investigators reviewed data for more than 160,000 individuals aged 70 and over who participated in the NIH-AARP Diet and Health Study. They completed a questionnaire in 2004-2005 detailing their smoking use, and reported deaths were tracked until the end of 2011. Analyses conducted between 2014 and 2016 correlated age at death with self-reported age at smoking initiation and cessation and amount smoked after 70 years of age.
The 2004-2005 questionnaire assessed smoking intensity in cigarettes per day and smoking history through nine age periods. For this study, participants still smoking in their 70s were identified as current smokers, and former smokers were classified by the decade of life when quitting.
For the follow-up, the National Death Index Plus was used to determine deaths, while ICD-9 and ICD-10 codes for smoking-related mortality were used to further identify outcomes. These included lung cancer; other smoking-related cancers, including bladder, colorectal, esophageal, head and neck, kidney and renal pelvis, liver, pancreatic and stomach cancers, and acute myeloid leukemia; heart disease; stroke; diabetes; and respiratory disease (e.g., pneumonia, influenza, chronic obstructive pulmonary disease, and allied conditions).
Data were adjusted for age, sex, level of education, and alcohol use. Since NIH-AARP participants are predominantly white, adjusting for race did not affect the results and was not included in the final models.
At the beginning of the study (2004-2005), the median age of participants was 75 years. Almost 56 percent were former smokers and 6 percent were current smokers. Males were less likely (31 percent vs 48 percent of females) to be never-smokers. Males smoked more than females (18.2 pack years vs 11.6 pack years), and males were more likely to have started smoking before 15 years (19 percent vs 9.5 percent of female smokers).