46%, p<.001). Very light nondaily smokers smoked fewer CPD on average; started smoking at an older age; and were less nicotine dependent, more likely to have made a Temsirolimus mTOR recent quit attempt, more likely to be planning to quit smoking soon, more likely to display self-efficacy regarding quitting, and more likely to smoke with friends. Longitudinal analyses We analyzed 2,664 two-year transitions for 2,008 smokers and 1,106 four-year transitions for as many smokers. Table 3 shows the results by four levels of baseline smoking. Among light smokers, the patterns of those consuming no more than 5 CPD on a nondaily basis differed from the others. Very light nondaily smoking was a stable pattern for many smokers, with nearly half of such smokers maintaining the pattern for 2 years and nearly one-third maintaining it for 4 years.

A substantial proportion of smokers consuming 6�C10 CPD also exhibited a stable smoking pattern; 40% were stable for 2 years and 24% were stable for 4 years. Very light daily smokers had significantly less stable smoking patterns than did other light smokers. Only 21% maintained their smoking status for 2 years (p=.03 vs. ��5 CPD, nondaily; p<.001 vs. 6�C10 CPD), and only 7% maintained it for 4 years (p=.003 vs. ��5 CPD, nondaily; p=.001 vs. 6�C10 CPD). Both very light nondaily smokers and smokers consuming 6�C10 CPD were significantly less likely to increase their cigarette consumption more than 2 years (20% and 19%, respectively) compared with very light daily smokers (32%; p<.001 and p=.03, respectively).

Very light nondaily smokers also were more likely than very light daily smokers to quit during follow-up, although the difference was not statistically significant. Smokers consuming 6�C10 CPD were significantly less likely to quit than very light nondaily smokers (p=.003 at 4 years), but they were not less likely to quit than very light daily smokers. Smokers consuming more than 10 CPD were a highly stable group, with 72% continuing to smoke at this minimum level after 2 years and 65% after 4 years. They were less likely to quit smoking than smokers at lower levels of consumption. Table 3. Two- and four-year trajectories by baseline smoking status Table 4 presents results from multivariate longitudinal analyses used to identify factors independently associated with 2-year transitions in smoking status (either quitting/reducing or increasing smoking) among two groups of light smokers categorized by cigarette consumption (��5 CPD, 6�C10 CPD) at the start of the follow-up period.

Drug_discovery The analyses identified different factors for these two groups. Plans to quit in the next 30 days and household smoking bans were associated with an increased likelihood of quitting over the 2-year follow-up period in the very light smoker group (��5 CPD).