Smoking onset has 4 levels, with a "susceptibility" level preceding early experimentation. This study assessed the predictive validity of smoking susceptibility in a longitudinal study of a nationally representative sample of 4,500 adolescents who at baseline reported never having puffed on a cigarette. At follow-up 4 years later, 40% of the sample had experimented with smoking, and 8% had established a smoking habit. Baseline susceptibility to smoking, defined as the absence of a firm decision not to smoke, was a stronger independent predictor of experimentation than the presence of smokers among either family or the best friend network. However, susceptibility to smoking was not as important as exposure to smokers in distinguishing adolescents who progressed to established smoking from those who remained experimenters at follow-up.

Context.-Whether tobacco advertising and promotion increases the likelihood that youths will begin smoking has important public policy implications. Objective.-To evaluate the association between receptivity to tobacco advertising and promotional activities and progress in the smoking uptake process, defined sequentially as never smokers who would not consider experimenting with smoking, never smokers who would consider experimenting, experimenters (smoked at least once but fewer than 100 cigarettes), or established smokers (smoked at least 100 cigarettes). Design.-Prospective cohort study with a 3-year follow-up through November 1996. Setting and Participants.-A total of 1752 adolescent never smokers who were not susceptible to smoking when first interviewed in 1993 in a population-based random-digit dial telephone survey in California were reinterviewed in 1996. Main Outcome Measure.-Becoming susceptible to smoking or experimenting by 1996. Results.-More than half the sample (n=979) named a favorite cigarette advertisement in 1993 and Joe Camel advertisements were the most popular. Less than 5% (n=92) at baseline possessed a promotional item but a further 10% (n=172) were willing to use an item. While having a favorite advertisement in 1993 predicted which adolescents would progress by 1996 (odds ratio [OR] =1.82; 95% confidence interval [CI], 1.04-3.20), possession or willingness to use a promotional item was even more strongly associated with future progression (OR=2.89; 95% CI, 1.47-5.68). From these data, we estimate that 34% of all experimentation in California between 1993 and 1996 can be attributed to tobacco promotional activities. Nationally, this would be over 700 000 adolescents each year. Conclusion.-These findings provide the first longitudinal evidence to our knowledge that tobacco promotional activities are causally related to the onset of smoking.

A randomized controlled trial of alternative dialysis modalities in ARF is feasible. Despite the potential advantages of continuous techniques, this study provides no evidence of a survival benefit of continuous hemodiafiltration compared with IHD. This study did not control for other major clinical decisions or other supportive management strategies that are widely variable (for example, nutrition support, hemodynamic support, timing of initiation, and dose of dialysis) and might materially influence outcomes in ARF. Standardization of several aspects of care or extremely large sample sizes will be required to answer optimally the questions originally posed by this investigation.