Prevalence of Heavy Smoking in California and the United States, 1965-2007

Context The intensity of smoking, not just prevalence, is associated with future health consequences. Objective To estimate smoking intensity patterns over time and by age within birth cohorts for California and the remaining United States. Design, Setting, and Participants Two large population-based surveys with state estimates: National Health Interview Surveys, 1965-1994; and Current Population Survey Tobacco Supplements, 1992-2007. There were 139 176 total respondents for California and 1 662 353 for the remaining United States. Main Outcome Measure Number of cigarettes smoked per day (CPD), high-intensity smokers (>= 20 CPD); moderate-intensity smokers (10-19 CPD); low-intensity smokers (0-9 CPD). Results In 1965, 23.2% of adults in California (95% confidence interval [CI], 19.6%-26.8%) and 22.9% of adults in the remaining United States (95% CI, 22.1%-23.6%) were high-intensity smokers, representing 56% of all smokers. By 2007, this prevalence was 2.6% (95% CI, 0.0%-5.6%) or 23% of smokers in California and 7.2% (95% CI, 6.4%-8.0%) or 40% of smokers in the remaining United States. Among individuals (US residents excluding California) born between 1920-1929, the prevalence of moderate/high-intensity smoking (>= 10 CPD) was 40.5% (95% CI, 38.3%-42.7%) in 1965. Moderate/high-intensity smoking declined across successive birth cohorts, and for the 1970-1979 birth cohort, the highest rate of moderate/high-intensity smoking was 9.7% (95% CI, 7.7%-11.7%) in California and 18.3% (95% CI, 16.4%-20.2%) in the remaining United States. There was a marked decline in moderate/high-intensity smoking at older ages in all cohorts, but this was greater in California. By age 35 years, the prevalence of moderate/high-intensity smoking in the 19701979 birth cohort was 4.6% (95% CI, 3.0%-6.1%) in California and 13.5% (95% CI, 11.8%-15.1%) in the remaining United States. Conclusions Between 1965 and 2007, the prevalence of high-intensity smoking decreased greatly in the United States. The greater decline in high-intensity smoking prevalence in California was related to reduced smoking initiation and a probable increase in smoking cessation. JAMA. 2011;305(11):1106-1112 www.jama.com