The findings in this report are subject to at least six limitations.
First, the estimates understate deaths attributable to tobacco use because
estimates of deaths attributable to cigar smoking, pipe smoking, and smokeless
tobacco use were excluded. Second, RRs were based on deaths during 1982-1988
among birth cohorts who might have had different smoking histories than current
or former smokers (e.g., age of initiation and duration of smoking before
quitting). Third, this report used a death certificate–based definition
of COPD, including codes for bronchitis/emphysema and chronic airway obstruction
(ICD-10 J44).1 Therefore, the COPD SAM estimate used for this report
might differ from other estimates that use other definitions of COPD.1 Fourth, RRs were adjusted for the effects
of age but not for other potential confounders. However, research suggests
that education, alcohol, and other confounders had negligible additional impact
on SAM estimates for lung cancer, COPD, ischemic heart disease, and cerebrovascular
disease in CPS-II.2 Fifth, productivity losses understate the total
costs of smoking because costs associated with smoking-attributable health-care
expenditures, smoking-related disability, employee absenteeism, and secondhand
smoke–attributable disease morbidity and mortality were not included.
Finally, the estimates do not account for the sampling variability in smoking
prevalence estimates or in RRs.