Gestational hypertension and preeclampsia in living kidney donors.

BACKGROUND: Young women wishing to become living kidney donors frequently ask whether nephrectomy will affect their future pregnancies. METHODS: We conducted a retrospective cohort study of living kidney donors involving 85 women (131 pregnancies after cohort entry) who were matched in a 1:6 ratio with 510 healthy nondonors from the general population (788 pregnancies after cohort entry). Kidney donations occurred between 1992 and 2009 in Ontario, Canada, with follow-up through linked health care databases until March 2013. Donors and nondonors were matched with respect to age, year of cohort entry, residency (urban or rural), income, number of pregnancies before cohort entry, and the time to the first pregnancy after cohort entry. The primary outcome was a hospital diagnosis of gestational hypertension or preeclampsia. Secondary outcomes were each component of the primary outcome examined separately and other maternal and fetal outcomes. RESULTS: Gestational hypertension or preeclampsia was more common among living kidney donors than among nondonors (occurring in 15 of 131 pregnancies [11%] vs. 38 of 788 pregnancies [5%]; odds ratio for donors, 2.4; 95% confidence interval, 1.2 to 5.0; P=0.01). Each component of the primary outcome was also more common among donors (odds ratio, 2.5 for gestational hypertension and 2.4 for preeclampsia). There were no significant differences between donors and nondonors with respect to rates of preterm birth (8% and 7%, respectively) or low birth weight (6% and 4%, respectively). There were no reports of maternal death, stillbirth, or neonatal death among the donors. Most women had uncomplicated pregnancies after donation. CONCLUSIONS: Gestational hypertension or preeclampsia was more likely to be diagnosed in kidney donors than in matched nondonors with similar indicators of baseline health. (Funded by the Canadian Institutes of Health Research and others.).

Risk of serious gastrointestinal bleeding in living kidney donors.

Individuals with moderate-to-severe reduced renal function have greater risk of gastrointestinal bleeding than those with normal renal function. We conducted a retrospective matched cohort study to assess whether living kidney donors share a similar risk. We reviewed pre-donation charts for living kidney donations from 1992 to 2009 in Ontario, Canada, and linked this information to healthcare databases. We selected healthy non-donors from the general population and matched ten non-donors to every donor. Of the 2009 donors and 20,090 matched non-donors, none had evidence of gastrointestinal bleeding prior to cohort entry. The cohort was followed for a median of 8.4 yr (maximum 19.7 yr; loss to follow-up <7%). There was no significant difference in the rate of hospitalization with gastrointestinal bleeding in donors compared to non-donors (18.5 vs. 14.9 events per 10,000 person-years; rate ratio 1.24; 95% confidence interval [CI] 0.85-1.81). Similar results were obtained when we assessed the time to first hospitalization with gastrointestinal bleeding (hazard ratio 1.25, 95% CI 0.87-1.79). In conclusion, we found living kidney donation was not associated with a higher risk of hospitalization with gastrointestinal bleeding. These results are reassuring for the safety of the practice.

E-cigarette use by Ontario public elementary school and secondary school students: Has the use among sociodemographic groups changed from 2017 to 2019?

This project examined e-cigarette use among Elementary School (ES) (grades 7 and 8) and Secondary School (SS) (grades 9-12) students in Ontario, Canada, for 2017 and 2019 and relationships with sociodemographic variables and traditional cigarette use. The data came from the Ontario Student Drug Use and Health Survey OSDUHS (2017, 2019). Socio-demographics included grade, school performance, sex, race, years in Canada, living arrangements and language spoken at home. E-cigarette use and cigarette smoking were any past year use. For 2017, there are a greater percentage of ES males than females who used e-cigarettes, older students, those living in more than one home and those smoking cigarettes. For SS students a greater percentage for those of older age, higher grades, living in Canada all their lives, using only English language at home, self-identified as white, with lower school performance, those with multiple household living arrangements and who reported smoking traditional cigarettes reported using e-cigarettes. Use was lower among females in 2017 (OR = 0.63, 95% CI = 0.46, 0.86, p = 0.002), but by 2019 use was higher among females, which resulted in a non-significant difference between males and females (OR = 0.91, 95% CI = 0.77, 1.09). Greater use of e-cigarettes was found among students who smoked traditional cigarettes compared to those who did not smoke in both years. Monitoring the trends, patterns and trajectories of use and variables related to use needs to be continued which may help inform the development of further legislative and educational measures.

Informing the debate: rates of kidney transplantation in nations with presumed consent.

BACKGROUND: The kidney is the most common transplanted organ, accounting for almost all living donor transplantations and most deceased donor organ transplantations. The organ shortage has caused policymakers in many nations to debate the merits of adopting presumed consent legislation as a way to increase donor organ donation from deceased donors. OBJECTIVE: To compare characteristics and kidney transplantation rates for countries with presumed consent for deceased organ donation with countries with explicit consent. DESIGN: A longitudinal study of international kidney transplantation from 1997 to 2007. SETTING: 44 nations performing kidney transplantation. PATIENTS: Recipients of deceased and living kidney donor transplants. MEASUREMENTS: Rates of transplantation of kidneys from deceased and living donors. RESULTS: National characteristics, such as population size, proportion of the population self-identified as Catholic, per capita gross domestic product, health expenditures, and physician density, varied widely for the 22 nations with presumed consent and the 22 nations with explicit consent. Deceased donor kidney transplantation rates were higher in nations with presumed consent (median, 22.6 transplantations per million population [pmp]; interquartile range [IQR], 9.3 to 33.8) versus nations with explicit consent (median, 13.9 transplantations pmp; IQR, 3.6 to 23.1). Living donor kidney transplantation rates were lower in nations with presumed consent (median, 2.4 transplantations pmp; IQR, 1.7 to 4.3) versus nations with explicit consent (median, 5.9 transplantations pmp; IQR, 2.3 to 12.2). The findings were consistent when nations were classified according to per capita gross domestic product, health expenditures, and physician density. LIMITATION: As with any observational study, associations may not be causal. CONCLUSION: Nations with presumed consent have higher rates of deceased donor kidney transplantation than nations with explicit consent. Any nation deciding to adopt presumed consent should carefully consider and reduce any negative effect on rates of living donation. PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research and Lawson Health Research Institute.

Interval estimation for the area under the receiver operating characteristic curve when data are subject to error.

The area (A) under the receiver operating characteristic curve is commonly used to quantify the ability of a biomarker to correctly classify individuals into two populations. However, many markers are subject to measurement error, which must be accounted for to prevent understating their effectiveness. In this paper, we develop a new confidence interval procedure for A which is adjusted for measurement error using either external or internal replicated measurements. Based on the observation that A is a function of normal means and variances, we develop the procedure by recovering variance estimates needed from confidence limits for normal means and variances. Simulation results show that the procedure performs better than the previous ones based on the delta-method in terms of coverage percentage, balance of tail errors and interval width. Two examples are presented.

Variables related to tobacco use among young adults: are there differences between males and females?

We sought to determine the association of four categories (chunks) of variables: (1) demographic characteristics, (2) family and friends smoking and other drug use, (3) psychosocial factors and attitude, and (4) lifestyle factors to current smoking as compared to never smoking among Canadian young adults. A cohort of 1270 young adults, followed for 10 years, completed a self-administered questionnaire. In multivariable analyses, the best final model for both genders did not include the psychosocial and attitudinal categories, but did contain variables in the demographic, family and friends, and lifestyle categories. Interventions for reducing smoking among young adults may be similar for males and females, a conclusion that differs from conclusions based on findings from younger age groups.

Do predisposing and family background characteristics modify or confound the relationship between drinking frequency and alcohol-related aggression? A study of late adolescent and young adult drinkers.

The present study examined whether predisposing and family background characteristics confounded (common cause/general deviance theory) or modified (conditional/interactive theory) the association between drinking frequency and alcohol-related aggression. A secondary analysis of the US National Longitudinal Survey of Youth was conducted using a composite sample of drinkers, ages 17 to 21, from the 1994, 1996, and 1998 Young Adult surveys (n=602). No evidence of confounding of the relationship between drinking frequency and alcohol-related aggression was found. In addition, predisposing characteristics did not modify the association between drinking frequency and alcohol-related aggression. However, family background variables (mother's education and any poverty) were important explanatory variables for alcohol-related aggression among males, whereas recent aggression (fights at school or work) was an important predictor for females. Overall, lack of support for the conditional/interactive and common cause theories of the alcohol and aggression relationship suggests that alcohol has an independent explanatory role in alcohol-related aggression. In addition, the gender differences found in the present study highlight the need for more gender-focussed research on predictors of alcohol-related aggression, especially among adolescents and young adults.

Drinking patterns, drinking contexts and alcohol-related aggression among late adolescent and young adult drinkers.

AIMS: The main objectives of this study were to determine: (1) the relative roles of heavy episodic drinking (HED), drinking frequency and drinking volume in explaining alcohol-related aggression and (2) whether drinking context variables (i.e. usual drinking locations, typical drinking companions and extent of peer drinking) confound or modify the relationship between HED and alcohol-related aggression or whether they predict alcohol-related aggression independently. DESIGN: A secondary analysis of the US National Longitudinal Survey of Youth was conducted. Alcohol-related aggression (denoted fights after drinking) was measured based on self-reports of arguments or fights that occurred during or after drinking in the previous 12 months. PARTICIPANTS: A composite sample of drinkers, ages 17-21, from the 1994, 1996 and 1998 Young Adult surveys (n = 738) was used. FINDINGS: Frequency of drinking and drinking volume largely confounded the association between HED and fights after drinking. Usually drinking in public locations away from home versus private locations was found to be significantly associated with a greater likelihood of fights after drinking among females. Among males, usual drinking location modified the relationship between drinking frequency and alcohol-related aggression, with the greatest risk of aggression for males who drank frequently and usually drank in public locations away from home. CONCLUSIONS: Programs designed to reduce drinking frequency in this population and to increase the safety of drinking locations in public places away from home may prove to be beneficial in reducing alcohol-related aggression.

Socioeconomic status and non-fatal injuries among Canadian adolescents: variations across SES and injury measures.

BACKGROUND: While research to date has consistently demonstrated that socioeconomic status (SES) is inversely associated with injury mortality in both children and adults, findings have been less consistent for non-fatal injuries. The literature addressing SES and injury morbidity among adolescents has been particularly inconclusive. To explore potential explanations for these discrepant research findings, this study uniquely compared the relationship across different measures of SES and different causes of injury (recreation versus non-recreation injuries) within a sample of Canadian adolescents. METHODS: The sample included adolescent participants (aged 12 to 19 years) in the Canadian 1996-1997 cross-sectional National Population Health Survey (n = 6967). Five SES measures (household income, two neighbourhood-level proxy measures, two parental indicators) were examined in relation to three injury outcomes (total, recreation, and non-recreation injuries) using multivariable logistic regression. RESULTS: Among males, a clear relationship with injury was observed only for a parental SES index, which was positively associated with total and recreation injuries (odds ratios for the highest versus lowest SES category of 1.9 for total and 2.5 for recreation injuries). Among females, there was some evidence of a positive relationship between SES and injuries, particularly for a neighbourhood-level education measure with total and recreation injuries (odds ratios of 1.7 for total and 2.0 for recreation injuries). CONCLUSION: The results suggest that differences related to the measures of SES chosen and the causes of injury under study may both contribute to discrepancies in past research on SES and non-fatal injuries among adolescents. To clarify the potential SES-injury relationship among youth, the findings emphasize a need for a greater understanding of the meaning and relevance of different SES measures for adolescents, and for an exploration of the pathways through which SES may be related to injury risk.

Is there value in using physician billing claims along with other administrative health care data to document the burden of adolescent injury? An exploratory investigation with comparison to self-reports in Ontario, Canada.

BACKGROUND: Administrative health care databases may be particularly useful for injury surveillance, given that they are population-based, readily available, and relatively complete. Surveillance based on administrative data, though, is often restricted to injuries that result in hospitalization. Adding physician billing data to administrative data-based surveillance efforts may improve comprehensiveness, but the feasibility of such an approach has rarely been examined. It is also not clear how injury surveillance information obtained using administrative health care databases compares with that obtained using self-report surveys. This study explored the value of using physician billing data along with hospitalization data for the surveillance of adolescent injuries in Ontario, Canada. We aimed i) to document the burden of adolescent injury using administrative health care data, focusing on the relative contribution of physician billing information; and ii) to explore data quality issues by directly comparing adolescent injuries identified in administrative and self-report data. METHODS: The sample included adolescents aged 12 to 19 years who participated in the 1996-1997 cross-sectional Ontario Health Survey, and whose survey responses were linked to administrative health care datasets (N = 2067). Descriptive analysis was used to document the burden of injuries as a proportion of all physician care by gender and location of care, and to examine the distribution of both administratively-defined and self-reported activity-limiting injuries according to demographic characteristics. Administratively-defined and self-reported injuries were also directly compared at the individual level. RESULTS: Approximately 10% of physician care for the sample was identified as injury-related. While 18.8% of adolescents had self-reported injury in the previous year, 25.0% had documented administratively-defined injury. The distribution of injuries according to demographic characteristics was similar across data sources, but congruence was low at the individual level. Possible reasons for discrepancies between the data sources included recall errors in the survey data and errors in the physician billing data algorithm. CONCLUSION: If further validated, physician billing data could be used along with hospital inpatient data to make an important and unique contribution to adolescent injury surveillance. The limitations inherent in different datasets highlight the need to continue rely on multiple information sources for complete injury surveillance information.

The potential effectiveness of warning labels on cigarette packages: the perceptions of young adult Canadians.

BACKGROUND: Since 1989 when health warning labels appeared on Canadian cigarette packages, the labels have changed from text only covering less than one quarter of the package to text and graphics covering over half the package. This study examines how Canadians in their 20s feel about the current graphic warning labels and their potential to prevent smoking and encourage quitting. METHODS: Participants between 20 and 24 years of age were part of a 10-year cohort study begun when the group was in Grade 6, with the purpose of examining factors that may affect smoking. Five questions about warning labels were added to the 2002 questionnaire requesting information on perceptions of the labels and their potential impact on smoking behaviours of young adults. One item had been included in previous questionnaires. RESULTS: 32.8% (n = 1267) of the respondents were smokers, with males (35.6%) being more likely to smoke than females (30.4%). Current smokers were less likely than experimental/ex-smokers to believe that warning labels with stronger messages would make people their age less likely to smoke. Female current smokers were more likely to think about quitting. CONCLUSION: Despite the efforts taken in developing the labels, some young adults are skeptical about their effects. Warning labels may have to be modified to target issues that are relevant to young adults; gender differences are important in this modification. Warning labels can offer an additional component to a comprehensive tobacco control program, in that they provide health information.

Corrigendum to "population-based placental weight ratio distributions".

[This corrects the article DOI: 10.1155/2014/291846.].

Longitudinal study of determinants of dependence in an elderly population.

OBJECTIVES: To describe those factors, from the host of initial measures in ambulatory, independent older men and women, that were determinants of becoming dependent over an 8-year follow-up. DESIGN: Initial measures in a cohort of independent older adults were used in logistic regression to describe the determinants of becoming dependent at the 8-year follow-up. SETTING: London, Ontario. PARTICIPANTS: Three hundred seventy-three men and women aged 55 to 86. MEASUREMENTS: Initial variables included body size, presence of chronic disease, maximal oxygen uptake (VO2max), strength, flexibility, walking pace, and leisure time physical activity. RESULTS: An 8-year follow-up of 297 participants identified 43 as dependent. Logistic regression showed age, presence of disease, and VO2max (cardiorespiratory fitness) at baseline to have significant odds ratios related to the outcome of becoming dependent. Controlling for other factors, a lower VO2max increased the odds of dependence by 14% for each mL/kg.min. CONCLUSION: Lower cardiorespiratory fitness was a significant determinant of becoming dependent in an 8-year follow-up of older adults. Initiatives to encourage physical activity in older adults should emphasize exercise, such as brisk walking, to maintain or improve cardiorespiratory fitness.

Can primary care doctors prescribe exercise to improve fitness? The Step Test Exercise Prescription (STEP) project.

BACKGROUND: Sedentary lifestyle is associated with adverse health outcomes. Available evidence suggests that, despite positive attitudes toward regular exercise in promoting a healthy lifestyle, few physicians actually prescribe exercise for their patients. Barriers include lack of skills and standard office instruments. Because primary care physicians have regular contact with a large proportion of the population, the impact of preventive health interventions may be great. OBJECTIVES: To determine the effect of an exercise prescription instrument (i.e., Step Test Exercise Prescription [STEP]), compared to usual-care exercise counseling delivered by primary care doctors on fitness and exercise self-efficacy among elderly community-dwelling patients. DESIGN: Randomized controlled trial; baseline assessment and intervention delivery with postintervention follow-up at 3, 6, and 12 months. SETTING: Four large (>5000 active patient files) academic, primary care practices: three in urban settings and one in a rural setting, each with four primary care physicians; two clinics provided the STEP intervention and two provided usual care control. PARTICIPANTS: A total of 284 healthy community-dwelling patients (72 per clinic) aged >65 years were recruited in 1998-1999. INTERVENTION: STEP included exercise counseling and prescription of an exercise training heart rate. MAIN OUTCOME MEASURES: The primary outcome measure was aerobic fitness (VO(2max)). Secondary outcomes included predicted VO(2max) from the STEP test, exercise self-efficacy (ESE), and clinical anthropometric parameters. RESULTS: A total of 241 subjects (131 intervention, 110 control) completed the trial. VO(2max) was significantly increased in the STEP intervention group (11%; 21.3 to 24ml/kg/min) compared to the control group (4%; 22 to 23ml/kg/min) over 6 months (p <0.001), and 14% (21.3 to 24.9ml/kg/min) and 3% (22.1 to 22.8ml/kg/min), respectively, at 12 months (p <0.001). A similar significant increase in ESE (32%; 4.6 vs 6.8) was observed for the STEP group compared to the control group (22%; 4.2 vs 5.4) at 12 months (p < 0.001). Systolic blood pressure decreased 7.3% and body mass index decreased 7.4% in the STEP group, with no significant change in the control group (p <0.05). Exercise counseling time was significantly (p <0.02) longer in the STEP (11.7+/-3.0 min) compared to the control group (7.1+/-7.0 min), but more (p <0.05) subjects completed > or =80% of available exercise opportunities in the STEP group. CONCLUSIONS: Primary care physicians can improve fitness and exercise confidence of their elderly patients using a tailored exercise prescription (e.g., STEP). Further, STEP appears to maintain benefits to 12 months and may improve exercise adherence. Future study should determine the impact of combining cognitive/behavior change strategies with STEP.

Latent mixed Markov modelling of smoking transitions using Monte Carlo bootstrapping.

It has been established that measures and reports of smoking behaviours are subject to substantial measurement errors. Thus, the manifest Markov model which does not consider measurement error in observed responses may not be adequate to mathematically model changes in adolescent smoking behaviour over time. For this purpose we fit several Mixed Markov Latent Class (MMLC) models using data sets from two longitudinal panel studies--the third Waterloo Smoking Prevention study and the UWO smoking study, which have varying numbers of measurements on adolescent smoking behaviour. However, the conventional statistics used for testing goodness of fit of these models do not follow the theoretical chi-square distribution when there is data sparsity. The two data sets analysed had varying degrees of sparsity. This problem can be solved by estimating the proper distribution of fit measures using Monte Carlo bootstrap simulation. In this study, we showed that incorporating response uncertainty in smoking behaviour significantly improved the fit of a single Markov chain model. However, the single chain latent Markov model did not adequately fit the two data sets indicating that the smoking process was heterogeneous with regard to latent Markov chains. It was found that a higher percentage of students (except for never smokers) changed their smoking behaviours over time at the manifest level compared to the latent or true level. The smoking process generally accelerated with time. The students had a tendency to underreport their smoking behaviours while response uncertainty was estimated to be considerably less for the Waterloo smoking study which adopted the 'bogus pipeline' method for reducing measurement error while the UWO study did not. For the two-chain latent mixed Markov models, incorporating a 'stayer' chain to an unrestricted Markov chain led to a significant improvement in model fit for the UWO study only. For both data sets, the assumption for the existence of an independence chain did not lead to significant improvement in model fit. The unrestricted two-chain latent mixed Markov model led to a significant improvement of model fit compared to a simple latent Markov model, but this model was overparameterized when the latent transition probabilities and/or response probabilities were assumed nonstationary. For the other models, the manifest/latent transition probabilities and response probabilities (for the four-wave Waterloo study only) were tested to be nonstationary for both data sets.

Population-based placental weight ratio distributions.

The placental weight ratio (PWR) is a health indicator that reflects the balance between fetal and placental growth. The PWR is defined as the placental weight divided by the birth weight, and it changes across gestation. Its ranges are not well established. We aimed to establish PWR distributions by gestational age and to investigate whether the PWR distributions vary by fetal growth adequacy, small, average, and large for gestational age (SGA, AGA, and LGA). The data came from a hospital based retrospective cohort, using all births at two London, Ontario hospitals in the past 10 years. All women who delivered a live singleton infant between 22 and 42 weeks of gestation were included (n = 41441). Nonparametric quantile regression was used to fit the curves. The results demonstrate decreasing PWR and dispersion, with increasing gestational age. A higher proportion of SGA infants have extreme PWRs than AGA and LGA, especially at lower gestational ages. On average, SGA infants had higher PWRs than AGA and LGA infants. The overall curves offer population standards for use in research studies. The curves stratified by fetal growth adequacy are the first of their kind, and they demonstrate that PWR differs for SGA and LGA infants.

Evidence-based sample size estimation based upon an updated meta-regression analysis.

A traditional meta-analysis examines the overall effectiveness of an intervention by producing a pooled estimate of treatment efficacy. In contrast to this, a meta-regression model seeks to determine whether a study-level covariate (X) is a plausible source of heterogeneity in a set of treatment effects. Upon performing such an analysis, the results may suggest the presence of a meaningful amount of variation in the treatment effects because of the covariate; however, the current set of trials may not provide sufficient statistical power for such a conclusion. The proposed approach provides quantitative insight into the amount of support that a new trial may provide to the hypothesis that X is a meaningful source of variation in an updated meta-regression model, which includes both the previously completed and the proposed trial. This empirical algorithm allows examination of the potential feasibility of a planned study of various sizes to further support or refute the hypothesis that X is a statistically significant source of variation. A detailed example illustrates the sample size estimation algorithm for both a planned individually or cluster randomized trial to investigate the now commonly accepted impact of geographical latitude on the observed effectiveness of the Bacillus Calmette-Guérin vaccine in the prevention of tuberculosis. Copyright © 2012 John Wiley & Sons, Ltd.

Holographically directed assembly of polymer nanocomposites.

Layered polymer/nanoparticle composites have been created through the one-step two-beam interference lithographic exposure of a dispersion of 25 and 50 nm silica particles within a photopolymerizable mixture at a wavelength of 532 nm. The polymerizable mixture is composed of pentaerythritol triacrylate (monomer), 1-vinyl-2-pyrrolidinone (monomer), and photoinitiator. In the areas of constructive interference, the monomer begins to polymerize via a free-radical process and concurrently the nanoparticles move into the regions of destructive interference. The effects of exposure time, power density, nanoparticle size, and periodicity on the final nanocomposite structure were measured with transmission electron microscopy to determine the mechanism for particle segregation. Diffraction from the sample was monitored as well, though its magnitude was not a good predictor of nanostructure in this relatively low index contrast system. Exposure time did not have a strong effect on the final structure. The best nanoparticle sequestration was observed at reduced laser power density, smaller interferogram periodicity, and decreased nanoparticle size, indicating that particle segregation is dominated by diffusion-limited nanoparticle transport directed by a matrix containing a gradient of polymerization kinetics.

Identifying the determinants of childhood immunization in the Philippines.

A key method of reducing morbidity and mortality is childhood immunization, yet in 2003 only 69% of Filipino children received all suggested vaccinations. Data from the 2003 Philippines Demographic Health Survey were used to identify risk factors for non- and partial-immunization. Results of the multinomial logistic regression analyses indicate that mothers who have less education, and who have not attended the minimally-recommended four antenatal visits are less likely to have fully immunized children. To increase immunization coverage in the Philippines, knowledge transfer to mothers must improve.

How are lifetime polytobacco users different than current cigarette-only users? Results from a Canadian young adult population.

Current cigarette smoking combined with ever use of other tobacco products (lifetime polytobacco use) is important to examine as users may be at greater risk for illicit drug use, nicotine addiction, and adverse health outcomes. We determined estimates and patterns of lifetime polytobacco use and conducted multivariable analyses to determine demographic, family and friend, psychosocial, and lifestyle factors associated with use among a sample of Canadian young adults. Overall prevalence was 36.3% for current cigarette use; 10.1% for current cigarette use only and 26.2% for lifetime polytobacco use. Among polytobacco users, current cigarette use and ever cigar use was most frequent (67.2%). For males, the final model contained demographic, family and friends, and lifestyle factors. For females, the final model also included psychosocial factors. Illicit drug use was the strongest significant predictor for lifetime polytobacco use among males. We found gender specific differences when comparing lifetime polytobacco users to current cigarette-only users, in particular; male lifetime polytobacco users were more likely to use drugs and alcohol. Interventions focusing on individual substances should consider addressing combinations of use.