摘要：Objectives. We examined changes in the relative risk of death among current and former smokers over recent decades in the United States. Methods. Data from the National Health Interview Survey (NHIS) and National Health and Nutrition Examination Survey (NHANES) were linked to subsequent deaths. We calculated age-standardized death rates by gender and smoking status, and estimated multivariate discrete time logit regression models. Results. The risk of death for a smoker compared with that for a never-smoker increased by 25.4% from 1987 to 2006 based on NHIS data. Analysis of NHANES data from 1971 to 2006 showed an even faster annual increase in the relative risk of death for current smokers. Former smokers also showed an increasing relative risk of death, although the increase was slower than that among current smokers and not always statistically significant. These trends were not related to increasing educational selectivity of smokers or increased smoking intensity or duration among current smokers. Smokers may have become more adversely selected on other health-related variables. Conclusions. A continuing increase in the relative risk of death for current and former smokers suggests that the contribution of smoking to national mortality patterns is not decreasing as rapidly as would be implied by the decreasing prevalence of smoking among Americans. Many prospective cohort studies have documented an excess mortality among smokers relative to that among nonsmokers. However, the magnitude of the relative risk of death from smoking has varied from study to study. The size of the risk has obvious implications for the behavioral choices of individuals. It is also directly relevant to the interpretation of population-level variation in mortality. For example, smoking has been identified as a major contributor to the poor ranking of the United States in international comparisons of longevity, 1 to the worsening position of womens’ life expectancy relative to that of men in the United States, 2 and to the higher mortality of poorly educated relative to well-educated individuals in several countries. 3 An accurate identification of the relative risks of smoking, and trends therein, helps to clarify its role in population health. The largest studies of the excess mortality risks of smokers have been conducted by the American Cancer Society. In Cancer Prevention Study I (CPS-I), approximately 1.05 million volunteers were recruited in 1959 from 25 states. Cancer Prevention Study II (CPS-II) recruited a similar number of volunteers in 1982 from all 50 states. Participants in both studies were older, more educated, and more likely to be married than was the general US population. Whites made up 97% of CPS-I and 93% of CPS-II. 4 Comparisons of the risk of death among smokers and nonsmokers between these 2 studies showed that the ratio of mortality among smokers to that of nonsmokers rose between 1959 and 1965 and 1982 and 1986. 4–6 For example, the ratio of age-standardized death rates of current cigarette smokers to never-smokers over this interval rose from 1.7 to 2.3 among men and from 1.2 to 1.9 among women. 4 A similar increase in the relative risk of death for smokers was recorded in a study of British doctors begun in 1951. At age 60 years and older, the relative risk of death among smokers increased from 1.46 for those born in the 19th century to 2.19 for those born in the 20th century. 7 Rosenbaum et al. 8 demonstrated a similar increase over the period from 1966 and 1968 to 1987 using data from National Mortality Follow-back Surveys. We used data from the National Health Interview Survey (NHIS) to investigate (1) whether similar trends are observed in nationally representative cohort studies; (2) whether such trends extend beyond the period 1986 to 1987, the last period included in previous studies of trends in risk; (3) whether similar trends are observed among former smokers, who now outnumber current smokers older than 45 years 9 (former smokers were not included in the CPS analysis); and (4) whether an increase in the relative risk of death among smokers is attributable to increasing educational selectivity of smokers compared with nonsmokers or to changes in the intensity and duration of smoking among current smokers. Although we relied primarily on data from NHIS in this investigation, we also used data from the National Health and Nutrition Examination Survey (NHANES), another nationally representative data set. NHANES data extend over a longer period than those from NHIS but contain a much smaller number of observations.
