TUESDAY, March 15 (HealthDay News) -- Between 1965 and 2007, the prevalence of high-intensity smoking declined in California and in the remaining states, according to a study published in the March 16 issue of the Journal of the American Medical Association.
John P. Pierce, Ph.D., from the University of California San Diego in La Jolla, and colleagues estimated smoking intensity patterns from 1965 to 2007 in 139,176 individuals from California, and 1,662,353 from the remaining states. The number of cigarettes smoked per day (CPD) was the main outcome measure, and smokers were divided into three groups: high intensity (20 or more CPD), moderate intensity (10 to 19 CPD), and low intensity (zero to nine CPD).
The investigators found that 56 percent of all smokers were high-intensity smokers in 1965; whereas, in 2007, high-intensity smokers accounted for 23 percent of smokers in California and 40 percent of smokers in the remaining states. Prevalence of moderate- or high-intensity smoking in the United States, excluding California, was 40.5 percent in 1965 for the 1920 to 1929 birth cohort, and declined in subsequent birth cohorts. For the 1970 to 1979 birth cohort, the prevalence of moderate- or high-intensity smoking was 9.7 percent in California and 18.3 percent in the remaining states. By the age of 35, in the 1970 to 1979 cohort, prevalence of moderate- or high-intensity smoking had declined to 4.6 percent in California and 13.5 percent in the remaining states.
"Over the past 40 years, patterns of smoking have changed dramatically in the United States and reflect both reduced initiation and increased cessation," the authors write.