Purpose: Current measures of successful quitting are insensitive to changes induced by tobacco control activities. We evaluated whether changes in the incidence of successful quitting, a new measure of cessation, can inform policy makers how population subgroups responded.
Methods: Smokers from National Health Interview Surveys (NHIS) (1965 through 1992, n = 140,199) were used to determine the number of current smokers eligible to quit at the beginning of each year from 1950 through 1990. Incidence of quitting, computed for different demographic subgroups, was the ratio of those newly successfully quit each year to those eligible to quit.
Results: Overall, incidence increased over fivefold, from < 1% in 1950 to a still low 5% in 1990. When the health risks of smoking were first disseminated, middle-aged men had the highest quitting incidence. Gender differences in younger smokers occurred following the beginning of the public health campaign of the mid 1960s, as the dangers of smoking to the fetus were documented. Younger adult smokers appeared to increase quitting markedly in the 1970s, around the beginning of the nonsmokers' rights movement. Quitting patterns in middle-aged African Americans were similar to whites, although at much reduced levels. Younger African Americans had low quitting incidence until 1989. Incidence differed by educational attainment; regardless of age, during the 1970s and 1980s, those with some college increased their quitting incidence markedly.
Conclusion: Incidence of quitting is a sensitive indicator of relatively short-term changes in successful quitting in population subgroups and should facilitate evaluation efforts.