Patterns of Smoking and Unhealthy Alcohol Use Following Sexual Trauma Among U.S. Service Members.

In the first known longitudinal study of the topic, we examined whether experiencing sexual assault or sexual harassment while in the military was associated with increased risk for subsequent unhealthy alcohol use and smoking among U.S. service members in the Millennium Cohort Study (2001-2012). Adjusted complementary log-log models were fit to estimate the relative risk of (a) smoking relapse among former smokers (men: n = 4,610; women: n = 1,453); (b) initiation of unhealthy alcohol use (problem drinking and/or drinking over recommended limits) among those with no known history of unhealthy alcohol use (men: n = 8,459; women: n = 4,816); and (c) relapse among those previously reporting unhealthy alcohol use (men: n = 3,487; women: n = 1,318). Men who reported experiencing sexual assault while in the military had sixfold higher risk for smoking relapse: relative risk (RR) = 6.62; 95% confidence interval (CI) [2.34, 18.73], than men who did not. Women who reported experiencing sexual assault while in the military had almost twice the risk for alcohol relapse: RR = 1.73; 95% CI [1.06, 2.83]. There were no other significant associations. These findings suggest that men and women may respond differently following sexual trauma, and support future concerted policy efforts by military leadership to prevent, detect, and intervene on sexual assault.

Longitudinal Investigation of Smoking Initiation and Relapse Among Younger and Older US Military Personnel.

OBJECTIVES: We examined whether military service, including deployment and combat experience, were related to smoking initiation and relapse. METHODS: We included older (panel 1) and younger (panel 2) participants in the Millennium Cohort Study. Never smokers were followed for 3 to 6 years for smoking initiation, and former smokers were followed for relapse. Complementary log-log regression models estimated the relative risk (RR) of initiation and relapse by military exposure while adjusting for demographic, health, and lifestyle factors. RESULTS: Deployment with combat experience predicted higher initiation rate (panel 1: RR = 1.44; 95% confidence interval [CI] = 1.28, 1.62; panel 2: RR = 1.26; 95% CI = 1.04, 1.54) and relapse rate (panel 1 only: RR = 1.48; 95% CI = 1.36, 1.62). Depending on the panel, previous mental health disorders, life stressors, and other military and nonmilitary characteristics independently predicted initiation and relapse. CONCLUSIONS: Deployment with combat experience and previous mental disorder may identify military service members in need of intervention to prevent smoking initiation and relapse.

Psychosocial factors in adolescent nicotine dependence symptoms: a sample of high school juniors who smoke daily.

Cross-sectionally examined seven theory-guided psychosocial factors associated with nicotine dependence symptoms in a representative self-report survey of 794 Washington State high school junior daily smokers (93% participation). Outcomes were four nicotine dependence symptoms. Results showed that low self-efficacy for quitting smoking and being around adults who smoke were associated with a 3.48-10.35 and a 1.47-1.77 times higher odds, respectively, of each of the four nicotine dependence symptoms. These results, needing replication in a longitudinal study, suggest that interventions designed to enhance self-efficacy to quit smoking and counter adult smoking influences might reduce adolescent nicotine dependence.

Telephone-delivered Acceptance and Commitment Therapy for adult smoking cessation: a feasibility study.

BACKGROUND: Quitline smoking cessation counseling results in a mere 12% success rate. Testing of new telephone-delivered cessation counseling approaches is needed. OBJECTIVE: Determine the feasibility of the first telephone-delivered Acceptance and Commitment Therapy (ACT) intervention for smoking cessation. DESIGN: Fourteen adults (57% racial/ethnic minority, 8/14) in a single-arm study. Counselor proactively delivered a 5-session (90-min total) ACT telephone intervention for smoking cessation. Hypothesized ACT processes were self-reported at baseline and posttreatment. Smoking status was self-reported at baseline, 20-day posttreatment (93% retention, 13/14), and 12-month posttreatment (93% retention, 13/14). RESULTS: (a) Delivery length and duration: average of 3.5 calls and 81.9-min intervention duration. (b) Receptivity: 100% (14/14) felt respected by the counselor, 86% (12/14) said that intervention was a good fit, and 93% (13/14) said that intervention helped them quit. (c) ACT processes: (i) acceptance of physical cravings, emotions, and thoughts that cue smoking increased from baseline to posttreatment (p = .001, p = .038, and p = .085, respectively) and (ii) commitment to quitting increased from baseline to posttreatment (p = .01). (4) Intent-to-treat cessation outcomes: (i) at 20-day posttreatment, 43% (6/14) had not smoked the day of the survey and 29% (4/14) had not smoked in past 7 days and (ii) at 12-month posttreatment, 29% (4/14) had not smoked at all in past 12 months. These quit rates are over double the 12% quit rates of current standard telephone counseling. CONCLUSION: Telephone-delivered ACT shows promise for smoking cessation and warrants future testing in a well-powered randomized trial.

Psychological and social risk factors in adolescent smoking transitions: a population-based longitudinal study.

OBJECTIVE: This study longitudinally investigated psychological and social risk factors consistent with the Theory of Triadic Influence (TTI) as predictors of adolescent smoking transitions. DESIGN: Among 4218 adolescents, five psychological risk factors (i.e., parent-noncompliance, friend-compliance, rebelliousness, low achievement motivation, and thrill seeking) were assessed in 9th grade (age 14), two social influence risk factors (i.e., parents' and close friends' smoking) were assessed in Grades 3 (age 8) and 9 (age 14), respectively. MAIN OUTCOME MEASURES: Adolescent smoking transitions occurring between the 9th and 12th (ages 14-17) grade interval. RESULTS: The probabilities contributed by each of the five psychological risk factors to the overall probability of making a specific smoking transition were: 22% to 27% for the transition from never to trying smoking, 10% to 13% for the transition from trying to monthly smoking, and, for three of the five risk factors, 11% to 16% for the transition from monthly to daily smoking. For predicting trying smoking, the probability contributed by these psychological factors was greater than the probability contributed by each parent's and close friend's smoking. Parent-compliance had a higher contribution to the probability of trying smoking when an adolescent's parent smoked (p < .05), whereas friend-compliance had a higher contribution to the probability of trying smoking when an adolescent's friend smoked (p < .001). CONCLUSION: These psychological and social factors have an important influence on adolescent smoking transitions. Implications for TTI and smoking prevention interventions are discussed.

Smoking and drinking behaviors of military spouses: Findings from the Millennium Cohort Family Study.

INTRODUCTION: The associations between stressful military experiences and tobacco use and alcohol misuse among Service members are well documented. However, little is known about whether stressful military experiences are associated with tobacco use and alcohol misuse among military spouses. METHODS: Using 9872 Service member-spouse dyads enrolled in the Millennium Cohort Family Study, we employed logistic regression to estimate the odds of self-reported cigarette smoking, risky drinking, and problem drinking among spouses by Service member deployment status, communication regarding deployment, and stress associated with military-related experiences, while adjusting for demographic, mental health, military experiences, and Service member military characteristics. RESULTS: Current cigarette smoking, risky drinking, and problem drinking were reported by 17.2%, 36.3%, and 7.3% of military spouses, respectively. Current deployment was not found to be associated with spousal smoking or drinking behaviors. Communication about deployment experiences with spouses was associated with lower odds of smoking, but not with risky or problem drinking. Spouses bothered by communicated deployment experiences and those who reported feeling very stressed by a combat-related deployment or duty assignment had consistently higher odds of both risky and problem drinking. CONCLUSIONS: Our findings suggest that contextual characteristics about the deployment experience, as well as the perceived stress of those experiences, may be more impactful than the simple fact of Service member deployment itself. These results suggest that considering the impact of deployment experiences on military spouses reveals important dimensions of military community adaptation and risk.

Posttraumatic Stress Disorder Symptom Association With Subsequent Risky and Problem Drinking Initiation.

OBJECTIVES: Posttraumatic stress disorder (PTSD) and unhealthy alcohol use are commonly associated conditions. It is unknown whether specific symptoms of PTSD are associated with subsequent initiation of unhealthy alcohol use. METHODS: Data from the first 3 enrollment panels (n = 151,567) of the longitudinal Millennium Cohort Study of military personnel were analyzed (2001-2012). Complementary log-log models were fit to estimate whether specific PTSD symptoms and symptom clusters were associated with subsequent initiation of 2 domains of unhealthy alcohol use: risky and problem drinking (experience of 1 or more alcohol-related consequences). Models were adjusted for other PTSD symptoms and demographic, service, and health-related characteristics. RESULTS: Eligible study populations included those without risky (n = 31,026) and problem drinking (n = 67,087) at baseline. In adjusted analyses, only 1 PTSD symptom-irritability/anger-was associated with subsequent increased initiation of risky drinking (relative risk [RR] 1.05, 95% confidence interval [CI] 1.00-1.09) at least 3 years later. Two symptom clusters (dysphoric arousal [RR 1.17, 95% CI 1.11-1.23] and emotional numbing [RR 1.30, 95% CI 1.22-1.40]) and 5 symptoms (restricted affect [RR 1.13, 95% CI 1.08-1.19], sense of foreshortened future [RR 1.12, 95% CI 1.06-1.18], exaggerated startle response [RR 1.07, 95% CI 1.01-1.13], sleep disturbance [RR 1.11, 95% CI 1.07-1.15], and irritability/anger [RR 1.12, 95% CI 1.07-1.17]) were associated with subsequent initiation of problem drinking. CONCLUSIONS: Findings suggest that specific PTSD symptoms and symptom clusters are associated with subsequent initiation of unhealthy alcohol use.

Longitudinal Examination of the Influence of Individual Posttraumatic Stress Disorder Symptoms and Clusters of Symptoms on the Initiation of Cigarette Smoking.

OBJECTIVES: The aim of this study was to determine whether specific individual posttraumatic stress disorder (PTSD) symptoms or symptom clusters predict cigarette smoking initiation. METHODS: Longitudinal data from the Millennium Cohort Study were used to estimate the relative risk for smoking initiation associated with PTSD symptoms among 2 groups: (1) all individuals who initially indicated they were nonsmokers (n = 44,968, main sample) and (2) a subset of the main sample who screened positive for PTSD (n = 1622). Participants were military service members who completed triennial comprehensive surveys that included assessments of smoking and PTSD symptoms. Complementary log-log models were fit to estimate the relative risk for subsequent smoking initiation associated with each of the 17 symptoms that comprise the PTSD Checklist and 5 symptom clusters. Models were adjusted for demographics, military factors, comorbid conditions, and other PTSD symptoms or clusters. RESULTS: In the main sample, no individual symptoms or clusters predicted smoking initiation. However, in the subset with PTSD, the symptoms "feeling irritable or having angry outbursts" (relative risk [RR] 1.41, 95% confidence interval [CI] 1.13-1.76) and "feeling as though your future will somehow be cut short" (RR 1.19, 95% CI 1.02-1.40) were associated with increased risk for subsequent smoking initiation. CONCLUSIONS: Certain PTSD symptoms were associated with higher risk for smoking initiation among current and former service members with PTSD. These results may help identify individuals who might benefit from more intensive smoking prevention efforts included with PTSD treatment.

The role of schoolmates' smoking and non-smoking in adolescents' smoking transitions: a longitudinal study.

AIMS: The first longitudinal investigation of the extent to which same-age and older schoolmates' smoking and non-smoking are associated with adolescents' smoking transitions during three grade intervals. DESIGN: Same-age and older schoolmates' smoking and non-smoking were assessed when adolescents were at grades 5 (age 10), 7 (age 12) and 9 (age 14). Adolescents' smoking transitions were assessed at three grade intervals: 5th-7th (age 10-12), 7th-9th (age 12-14) and 9th-12th (age 14-17). SETTING: Forty Washington State school districts. PARTICIPANTS AND MEASUREMENTS: Smoking questionnaire data were gathered on a cohort of adolescents (n = 4354 for same-age schoolmate analysis; n = 1833 for older schoolmate analysis) that was 49% female and 91% Caucasian. FINDINGS: No significant evidence that same-age schoolmates' smoking or non-smoking was associated with any of the adolescent smoking transitions at any of the three grade intervals. In contrast, the probability that each older schoolmate's smoking was associated with the adolescent making the transition to trying smoking was 1% (95% CI: 0.4%, 1.5%) and with the transition from trying to monthly smoking was also 1% (95% CI: 0.2%, 2.0%) during the 7th-9th grade (age 12-14) interval. Moreover, each older schoolmate's non-smoking was associated with a 1.001-1.006 (all P < 0.05) relative risk of an adolescent not trying smoking or escalating from trying to monthly smoking at several grade intervals. CONCLUSIONS: Interventions should perhaps focus on the influence of both smoking and non-smoking older schoolmates during late childhood and early adolescence.

Changes in the influence of parents' and close friends' smoking on adolescent smoking transitions.

This paper examined changes in the influence of parents' and close friends' smoking on smoking transitions occurring over the course of adolescence, using a large (N=6,006) longitudinal study. The three grade periods were 5th to 7th (ages 10-12), 7th to 9th (ages 12-14), and 9th to 12th grade (ages 14-17). Smoking transitions examined were: (1) never to trying, (2) trying to monthly, and (3) monthly to daily. Results showed that the influence of parents' smoking was substantial for all three transitions during most of the grade periods and, for the transition from monthly to daily smoking, increased (p=.006) during adolescence. In contrast, the influence of close friends' smoking was strongest for the transition to trying smoking and did not significantly change (all p>.05) for any of the smoking transitions as the adolescent became older. In conclusion, the influence of close friends' smoking on smoking transitions might be stable during adolescence whereas the influence of parents' smoking on the transition to daily smoking might markedly increase across adolescence.

Late smoking relapse among adolescent quitters.

Whereas some data are available about late smoking relapse among adult quitters, there are none for teen quitters. This study is a 6-year follow-up of teen quitters (n=253) for whom we collected (retrospectively) data on the extent and timing of relapse. We found that even after a strictly defined quit (six-months prolonged abstinence) at one year, substantial relapse occurred both early and late: the majority (55%) of relapses occurred after the 0-1year interval after having quit. These findings have implication for the need for research into the relapse process for teen quitters, and for the need to develop interventions for teens (as for adults) to prevent (early and) late relapse.

Prospective prediction of children's smoking transitions: role of parents' and older siblings' smoking.

AIMS: To use a novel social epidemic probability model to investigate longitudinally the extent to which parents' and older siblings' smoking predict children's smoking transitions. DESIGN: Parents' and older siblings' smoking status was assessed when children were in 3rd grade (baseline). Three smoking transitions were assessed over the period of child/adolescent smoking acquisition (up to 12th grade): (1) transition from never smoking to trying smoking, (2) transition from trying to monthly smoking and (3) transition from monthly to daily smoking. SETTING: Forty Washington State school districts participating in the long term Hutchinson Smoking Prevention Project (HSPP). PARTICIPANTS AND MEASUREMENTS: Participants were the 5520 families for whom data on both parents' and older siblings' baseline smoking status, as well as on children's smoking transitions, were available. FINDINGS: The probability that a smoking parent influenced their child to make the first transition to trying smoking was 32% (95% CI: 27%, 36%); to make the second transition from trying to monthly smoking, 15% (95% CI: 10%, 19%); and to make the third transition from monthly to daily smoking, 28% (95% CI: 21%, 34%). The probability that an older sibling influenced a child to make the first transition to trying smoking was 29% (95% CI: 17%, 39%); to make the second transition from trying to monthly smoking, 0% (95% CI: 0%, 8%); and to make the third transition from monthly to daily smoking, 20% (95% CI: 4%, 33%). CONCLUSIONS: In contrast to previous research, the results provide new evidence suggesting that family smoking influences both initiation and escalation of children's smoking. Results also quantify, in terms of probabilities, the importance of parents' and older siblings' smoking on children's three major smoking transitions. Parents' smoking, as well as older siblings' smoking, are important behaviors to target in preventing adolescents from making smoking transitions.

Nine-year prediction of adolescent smoking by number of smoking parents.

For scientific and public health reasons, it is important to identify the role of family influences on child smoking acquisition. Using a well-followed (>90%) cohort of 3,012 children and their parents, this study prospectively investigated the influence of smoking by 0 vs. 1 vs. 2 parents when the children were young (3rd grade), on whether the children subsequently became daily smokers. It is the only study to investigate the prediction of child/adolescent smoking at the end of the smoking acquisition period (12th grade) by parental smoking at the start of the period (3rd grade). Logistic regression analyses revealed that having one parent who smokes substantially increases the risk that children will become daily smokers, relative to families where neither parent smokes (OR=1.90, p<.01). There is no evidence that the increased risk depends on parent or child gender. These results suggest the need for public health interventions that inform parents of young children that their own smoking behavior increases their children's risk for future smoking.

Childhood friends who smoke: do they influence adolescents to make smoking transitions?

This study investigated longitudinally the extent to which childhood friends who smoke influence adolescents' smoking transitions, and compared that influence with that of parents who smoke. In a sample of 4744 children, results showed that the probability, per close friend, that a smoking close friend influenced the adolescent to make the first transition to trying smoking was 38% (95% CI: 28%, 46%); to make the second transition from trying to monthly smoking, 10% (95% CI: 5%, 15%); and to make the third transition from monthly to daily smoking, 11% (95% CI: 5%, 17%). Compared to parents' smoking, close friends' smoking was 12% (p=0.03) more influential for the first transition, no different for the second transition (p=0.53), and 16% (p=0.01) less influential for the third transition. Results provide new evidence suggesting that childhood close friends who smoke influence not only initiation but also escalation of adolescents' smoking. Results also confirmed the important role of parents' smoking. Targeting both childhood close friends' and parents' smoking would be valuable in prevention research.

Does Effectiveness of Adolescent Smoking-Cessation Intervention Endure Into Young Adulthood? 7-Year Follow-Up Results from a Group-Randomized Trial.

BACKGROUND: The Hutchinson Study of High School Smoking was the first randomized trial to show effectiveness of a smoking cessation intervention on 6-months prolonged smoking abstinence at one year post-intervention in a large population-based sample of adolescent smokers. An important question remains: Do the positive effects from teen smoking cessation interventions seen at up to 12 months post-intervention endure into young adulthood? This study examines for the first time whether such positive early effects from teen smoking cessation intervention can endure into young adulthood in the absence of additional intervention. METHODS: High school smokers (n = 2,151) were proactively recruited into the trial from fifty randomly selected Washington State high schools randomized to the experimental (Motivational Interviewing + Cognitive Behavioral Skills Training telephone counseling intervention) or control (no intervention) condition. These smokers were followed to 7 years post high school to ascertain rates of six-year prolonged smoking abstinence in young adulthood. All statistical tests are two-sided. RESULTS: No evidence of intervention impact at seven years post high school was observed for the main endpoint of six-year prolonged abstinence, neither among all smokers (14.2% in the experimental condition vs. 13.1% in the control condition, difference = +1.1%, 95% confidence interval (CI) = -3.4 to 5.8, p = .61), nor among the subgroups of daily smokers and less-than-daily smokers, nor among other a priori subgroups. But, observed among males was some evidence of an intervention impact on two endpoints related to progress towards quitting: reduction in number of days smoked in the past month, and increase in the length of the longest quit attempt in the past year. CONCLUSIONS: There was no evidence from this trial among adolescent smokers that positive effectiveness of the proactive telephone intervention for smoking abstinence, observed previously at one year post-intervention, was sustained for the long-term into young adulthood. In light of the positive short-term effectiveness consistently observed from this and other trials for teen smokers, together with the lack of evidence from this study that such short-term impact can endure into young adulthood, sustained interventions that continue into young adulthood should be developed and tested for long-term impact. TRIAL REGISTRATION: ClinicalTrials.gov NCT00115882.

Proactive telephone counseling for adolescent smokers: Comparing regular smokers with infrequent and occasional smokers on treatment receptivity, engagement, and outcomes.

BACKGROUND: Adolescent smoking cessation efforts to date have tended to focus on regular smokers. Consequently, infrequent and occasional smokers' receptivity and response to smoking cessation interventions is unknown. To address this gap, this study examines data from the Hutchinson Study of High School Smoking-a randomized trial that examined the effectiveness of a telephone-delivered smoking cessation intervention for a large, population-based cohort of adolescent smokers proactively recruited in an educational setting. METHODS: The study population included 1837 proactively identified high school smokers. Intervention receptivity, engagement, and outcomes were examined among adolescent infrequent (1-4days/month) and occasional (5-19days/month) smokers and compared with regular smokers (20 or more days/month). RESULTS: With regard to treatment receptivity, intervention recruitment did not differ by smoking frequency. For engagement, intervention completion rates were higher for infrequent smokers (80.5%) compared with occasional (63.8%) and regular smokers (61.5%, p<0.01). Intervention effect sizes were not statistically different across groups. CONCLUSIONS: Adolescent infrequent and occasional smokers are at least as receptive to a proactively delivered smoking cessation intervention as regular smokers and can benefit just as much from it. Including these adolescent smokers in cessation programs and research-with the goal of interrupting progression of smoking before young adulthood-should help reduce the high smoking prevalence among young adults.

Does parental smoking cessation encourage their young adult children to quit smoking? A prospective study.

AIMS: To investigate the extent to which parental early and late smoking cessation predicts their young adult children's smoking cessation. DESIGN: Parental early smoking cessation status was assessed when children were in 3rd grade, parental late smoking cessation was assessed when children were in 11th grade, and young adult children's smoking cessation was assessed 2 years after high school. SETTING: Forty Washington State school districts participated in the Hutchinson Smoking Prevention Project. PARTICIPANTS AND MEASUREMENTS: Participants were the 1553 families in which parents were ever regular smokers who had a young adult child smoking at least weekly at 12th grade who also reported their smoking status 2 years later. Questionnaire data were gathered on parents and their young adult children (49% female and 91% Caucasian) in a cohort with a 94% retention rate. FINDINGS: Parents who quit early had children with 1.8 (OR = 1.80; 95% CI = 1.22, 2.64) times higher odds of quitting smoking for at least 1 month in young adulthood compared to those whose parents did not quit early. In contrast, there was no association (OR = 0.84; 95% CI = 0.47, 1.51) between parents quitting late and their young adult children's smoking cessation. CONCLUSIONS: Parental early smoking cessation is associated with increased odds of their young adult children's smoking cessation. Parents who smoke should be encouraged to quit when their children are young.

Antismoking parenting practices are associated with reduced rates of adolescent smoking.

BACKGROUND: Although parental smoking is clearly one important influence on children's smoking, it is still unclear what are the many mechanisms by which parents influence their children's smoking. Antismoking actions are one potential mechanism. OBJECTIVE: To determine whether parental antismoking actions including having rules about smoking in one's home, using nonsmoking sections of public establishments, or asking others not to smoke in one's presence are associated with adolescents' adoption of smoking. DESIGN: A cross-sectional survey. SETTING: Rural and suburban communities in western Washington State. PARTICIPANTS: Population-based cohort of 3555 adolescents and their parents. MAIN OUTCOME MEASURE: Daily smoking in 12th grade. RESULTS: Adolescents of parents who report having rules about smoking in one's home, using nonsmoking sections of public establishments, or asking others not to smoke in one's presence were significantly less likely to smoke than adolescents of parents who did not engage in antismoking actions. This association of antismoking action and reduced smoking was found for children of both smoking and nonsmoking parents. CONCLUSION: Parents' antismoking actions may help prevent smoking by their teenaged children.

Nine-year prospective relationship between parental smoking cessation and children's daily smoking.

AIMS: The first prospective investigation of the extent to which parental smoking cessation predicts their children's daily smoking. DESIGN: Parental smoking status was assessed when children were aged 8/9 years and children's smoking status was assessed at age 17/18 years. SETTING: Twenty Washington State school districts in the control group of the Hutchinson Smoking Prevention Project. PARTICIPANTS AND MEASUREMENTS: Questionnaire data were gathered on 3012 children (49% female and 91% Caucasian) and both of their parents in a cohort with a 95% retention rate. FINDINGS: When both parents quit smoking, children's odds of daily smoking were reduced by 39% (95% CI = 15%,56%) compared to when both parents were current smokers.Furthermore, when both parents never smoked then children's odds of daily smoking were reduced by 71% (95% CI = 62%,78%). CONCLUSIONS: Parental smoking cessation is associated with reduced risk of their children's daily smoking. Parents who quit still place children at substantially higher risk compared to parents who never smoked.

Nine-year prospective association between older siblings' smoking and children's daily smoking.

PURPOSE: To explore the hypothesis that older siblings' smoking, after controlling for parents' smoking, influences children's smoking. METHODS: Study participants were 2981 students in the control cohort of a school-based smoking prevention randomized trial for whom parents' smoking and older siblings' smoking data were collected at 3rd grade and daily smoking data was assessed 9 years later through a self-report questionnaire at the 12th grade. Data were analyzed using conditional logistic regression and likelihood ratio tests. RESULTS: For families in which no parent smoked, the 12th grade prevalence of daily smoking was 31% when at least one older sibling smoked compared to 18% when no older sibling smoked. For families in which at least one parent smoked, the 12th grade prevalence of daily smoking was 41% when at least one older sibling smoked compared to 29% when no older sibling smoked. There was a substantial increase in the odds (OR = 1.60, p =.004) of children's daily smoking at 12th grade when their older siblings smoked, even after adjusting for parents' smoking. CONCLUSIONS: Older siblings' smoking is associated with increased risk of children's smoking after adjusting for parents smoking. Furthermore, there was no evidence to suggest that the influence of older siblings' smoking was different in families where no parent smoked compared to those where at least one parent smoked. Also, there was no evidence that the influence of older siblings' smoking was different in boys vs. girls.