Reductions in Cigarettes per Day and Mortality Among Older Adults in The United States

Abstract

Many smokers do not quit but instead reduce the number of cigarettes that they smoke per day (CPD) over their lifetime, yet the associations of such changes in CPD with health risks are unclear. We examined the association of changes in CPD with subsequent mortality (2004-2011) among 253,947 participants of the NIH-AARP Diet and Health Study. We identified cigarette smokers who quit, decreased, maintained, or increased their CPD between ages 25-29 and 50-59 using a questionnaire assessing smoking history in 2004-2005. Hazard ratios (HR) and 95% confidence intervals (CI) were from multivariable-adjusted Cox proportional hazards regression. Relative to never smokers, smokers who maintained a consistent CPD had 2.93 times (95%CI: 2.82, 3.05) higher all-cause mortality risk, with still higher risks observed in participants who increased their CPD (HR: 3.37, 95%CI: 3.23, 3.52). Risks were lower among participants who decreased their CPD (HR: 2.38, 95%CI: 2.25, 2.52) or quit smoking (HR for quitting between 30-39 years: 1.32, 95%CI: 1.25, 1.39). Similar patterns were observed for smoking-related causes of death, with particularly strong associations for lung cancer and respiratory disease. Reductions in CPD over the lifetime meaningfully decrease mortality risk. But cessation provides a larger benefit than even large declines in CPD.