Cigarette Smoking Among Adults and Trends in Smoking Cessation

Cigarette smoking continues to be the leading cause of preventable morbidity and mortality in the United States. Full implementation of population-based strategies and clinical interventions can educate adult smokers about the dangers of tobacco use and assist them in quitting. To assess progress toward the Healthy People 2010 objective of reducing the prevalence of cigarette smoking among adults to < 12% (objective 27-1a), CDC analyzed data from the 2008 National Health Interview Survey (NHIS). This report summarizes the results of that analysis, which indicated that during 1998-2008, the proportion of U.S. adults who were current cigarette smokers declined 3.5% (from 24.1% to 20.6%). However, the proportion did not change significantly from 2007 (19.8%) to 2008 (20.6%). In 2008, adults aged ≥25 years with low educational attainment had the highest prevalence of smoking (41.3% among persons with a General Educational Development certificate [GED] and 27.5% among persons with less than a high school diploma, compared with 5.7% among those with a graduate degree). Adults with education levels at or below the equivalent of a high school diploma, who comprise approximately half of current smokers, had the lowest quit ratios (2008 range: 39.9% to 48.8%). Evidence-based programs known to be effective at reducing smoking should be intensified among groups with lower education, and health-care providers should take education level into account when communicating about smoking hazards and cessation to these patients.

The 2008 NHIS adult core questionnaire was administered by in-person interview and included 21,781 persons aged > 18 years from among the noninstitutionalized, U.S. civilian population. Respondents were selected by a random probability sample, and the survey included questions on cigarette smoking and cessation attempts. The overall response rate for the 2008 adult core questionnaire was 62.6%. To determine smoking status, respondents were asked, “Have you smoked at least 100 cigarettes in your entire life?” Those who answered “yes” were asked, “Do you now smoke cigarettes every day, some days, or not at all?” Ever smokers were defined as those who reported having smoked at least 100 cigarettes during their lifetime. Current smokers were those who had smoked at least 100 cigarettes during their lifetime and, at the time of interview, reported smoking every day or some days. Former smokers were those who reported smoking at least 100 cigarettes during their lifetime but currently did not smoke. Never smokers were those who reported never having smoked 100 cigarettes during their lifetime. Starting in 2007, income-related follow-up questions were added to NHIS to reduce the number of responses with unknown values. For this report, poverty status was defined by using 2006 poverty thresholds published by the U.S. Census Bureau for the 2007 estimates and 2007 poverty thresholds published by the U.S. Census Bureau for the 2008 estimates; family income was reported by the family respondent who might or might not have been the same as the sample adult respondent from whom smoking information was collected.

To measure trends in cigarette smoking cessation in the population, quit ratios were calculated as the ratio of former smokers to ever smokers for each survey year from 1998 to 2008. Quit ratios were analyzed by education level to determine if differing quit ratios accounted for part of the differing prevalence among education groups. Data were adjusted for nonresponse and weighted to provide national estimates of cigarette smoking prevalence; 95% confidence intervals were calculated using statistical analysis software to account for the survey’s multistage probability sample design. For year-to-year prevalence comparisons, statistical significance (p<0.05) was determined by using a two-sided t-test. Logistic regression analysis was used to analyze temporal changes in quit ratios during 1998-2008, controlling for sex, age, and race/ethnicity.

Overall smoking prevalence did not change significantly from 2007 to 2008. In 2008, an estimated 20.6% (46.0 million) of U.S. adults were current cigarette smokers; of these, 79.8% (36.7 million) smoked every day, and 20.2% (9.3 million) smoked some days. Among current cigarette smokers, an estimated 45.3% (20.8 million) had stopped smoking for 1 day or more during the preceding 12 months because they were trying to quit. Of the estimated 94 million persons who had smoked at least 100 cigarettes during their lifetime (ever smokers), 51.1% (48.1 million) were no longer smoking at the time of interview (former smoker).

In 2008, smoking prevalence was higher among men (23.1%) than women (18.3%). Among racial/ethnic groups, Asians had the lowest prevalence (9.9%), and Hispanics had a lower prevalence of smoking (15.8%) than non-Hispanic blacks (21.3%) and non-Hispanic whites (22.0%). American Indians/Alaska Natives had higher prevalence of current smoking compared with the other racial/ethnic groups (32.4%).

Variations in smoking prevalence in 2008 also were observed by education level. Smoking prevalence was highest among adults who had earned a General Education Development certificate (GED). Smoking prevalence was lowest among adults with a graduate degree (5.7%). The prevalence of current smoking was higher among adults living below the federal poverty level (31.5%) than among those at or above this level (19.6%). Smoking prevalence did not vary significantly for adults aged 18-24 years (21.4%), 25-44 years (23.7%), and 45-64 years (22.6%); however, smoking prevalence was lower for adults aged >65 years (9.3%).

During 1998-2008, the proportion of U.S. adults who were current cigarette smokers declined 3.5% (from 24.1% to 20.6% [p<0.05]), and a statistically significant downward trend was observed (p<0.05). In 2008, quit ratios were lower for adults aged >25 years with a GED (39.9%), adults with no high school diploma (45.7%), and adults with a high school diploma (48.8%), compared with quit ratios observed overall for adults aged >25 years (53.8%). During 1998-2008, the overall quit ratio was stable (or varied little) and ranged from 48.7% (1998) to 51.1% (2008). Persons with an undergraduate degree and persons with a graduate degree had quit ratios consistently higher than 60.0%. The only group with a significant upward linear trend in cessation was persons with a graduate degree; in 2008, the quit ratio was 80.7%, compared with 76.0% in 1998. Adults with a GED had the lowest quit ratio; during 1998-2008, their quit ratios ranged from 31.2% (2001) to 39.9% (2008).

Reported by: SR Dube, PhD, K Asman, MSPH, A Malarcher, PhD, R Carabollo, PhD, Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

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