94 (95% CI = 1.10�C3.43) and 1.62 (95% CI = 1.04�C2.57) times, respectively, over those in the Ganetespib IC50 late pubertal timing group. However, the risk for smoking initiation was not significantly different for early and on-time groups (HR = 1.19, 95% CI = 0.75�C1.89). The results showed that after adjusting for the covariates, there was no significant interaction effect between racial group and pubertal timing on smoking initiation, although there appeared to be racial group differences in the Kaplan�CMeier analysis. There was a main effect of pubertal timing for the total sample showing that late timing was associated with the lowest risk for smoking initiation (Figure 2). Figure 2. Survival functions for age at first cigarette by pubertal timing group via Cox regression.

Analysis accounted for the effects of age, race, SES, parent smoking, and friend smoking. The early and on-time groups are not significantly different from each … Discussion The present study examined the association between pubertal timing and age at first cigarette in a large sample of White and Black adolescent females. When Black and White groups were examined separately, early pubertal timing was associated with earlier age of smoking initiation in Black girls only. This was counter to expectations as most of the literature focuses on White samples and the findings between early timing and substance use are well supported (Dick et al., 2000; Lanza & Collins, 2002; Westling et al., 2008). However, when race was tested as a moderator, there was not a significant interaction between racial group and pubertal timing, but there was a main effect of pubertal timing.

Most studies have found that only early timing is associated with increased substance use. For example, girls with early puberty reported a younger age of first cigarette than those with later puberty (Wilson et al., 1994) and were 1.5 times more likely to smoke (Bratberg, Nilsen, Holmen, & Vatten, 2005). However, we found that early and on-time groups were at increased risk for early smoking initiation compared with the late timing group. Although previous research has demonstrated that White adolescents initiate smoking earlier, smoke more, and progress to becoming regular smokers more rapidly than Black adolescents (Harrell et al., 1998; Kandel, Kiros, Schaffran, & Hu, 2004), our study shows that a racial disparity may not exist when assessing the effect of pubertal timing on smoking behavior.

Late timing for both Whites and Blacks seems to be protective against early smoking initiation. Smoking behavior in adolescents, and especially early age at initiation, is particularly important when examining long-term smoking and health consequences. Youth who begin smoking in lower grades are more likely to be adult smokers (Chassin, Presson, Sherman, & Edwards, Dacomitinib 1990). Additionally, age of smoking initiation is a significant factor for failure in cessation attempts (Khuder, Dayal, & Mutgi, 1999).