Nicotine intake is generally expected to be relatively stable over time at least among regular established smokers, and therefore, one would expect that their Idelalisib clinical trial cigarette consumption would remain fairly stable over time (U.S. Department of Health and Human Services, 1988). Any increase in consumption over time usually indicates those who are still on the uptake trajectory (Chassin, Presson, Pitts, & Sherman, 2000; Costello, Dierker, Jones, & Rose, 2008). On the other hand, with increased awareness of the health consequences of smoking, one might expect that many smokers who are unwilling or unable to quit are likely to be looking for ways to reduce the harms of continual smoking (Hughes, 2000; Shiffman et al., 2002). One such strategy is to cut down the number of cigarettes smoked per day (Hughes & Carpenter, 2005).

As smoke-free places become more pervasive following increasing adoption of smoke-free policies in many countries as part of their efforts to protect their population from the harms of secondhand smoke, there are fewer and fewer public places where people can smoke (Hargreaves et al., 2010; Hopkins et al., 2010). As awareness of the harm of secondhand smoke increases, many smokers are also making efforts to not smoke at homes (Borland et al., 2006) and in private cars when in the presence of children (Hitchman, Fong, Borland, & Hyland, 2010). Thus, cigarette consumption is expected to diminish over time for continuing smokers either because of increasing external pressure to reduce or because of increased knowledge of the harm of smoking and passive smoking (Gilpin & Pierce, 2002).

Recent research also shows that smokers who have failed a quit attempt are more likely to return to a lower level of cigarette consumption, but then, the reduction in consumption diminishes over time (Knoke, Anderson, & Burns, 2006; Yong, Borland, Hyland, & Siahpush, 2008). Thus, reduced smoking following a failed quit attempt appears to be more temporary than permanent. Moreover, the pattern of a self-initiated smoking reduction may not Brefeldin_A necessarily be linear. It is possible that reduction in cigarette consumption is greatest initially but tapers off and reaches a plateau over time. This happens when at the initial stage smokers tend to give up the nonessential cigarettes, which are eliminated quite easily, but over time are left with the essential ones, which become increasingly more difficult to give up (Cheong, Yong, & Borland, 2007). The present study sought to investigate whether cigarette consumption of continuing adult smokers (those who are either unwilling or unable to quit) remained stable or decreased over time, using the first five waves of data collected from the International Tobacco Control Four-Country (ITC-4) Survey.