Abstract
Purpose
This study examines the role of perceived parental knowledge on initiation of nicotine and cannabis vaping among youth.
Design
Longitudinal study from a self-administered online survey. Three waves of data collected in 6-month intervals.
Setting
79 public and private schools in Texas.
Participants
Adolescents who self-reported never using e-cigarette to vape nicotine (n=1907; weighted sample [N] = 304371) or vape cannabis (n=2212; N=351955) at baseline. Participants were in 8th, 10th, and 12th grade at baseline.
Measures
Self-reported measures of nicotine and cannabis vaping.
Analyses
Weighted multivariate logistic regression models examined role of perceived parental knowledge at baseline (Spring 2016) as a predictor of nicotine and cannabis vaping initiation at 6-month (Fall 2016) and 12 month (Spring 2017) follow-up. Covariates were age, sex, race/ethnicity, and other tobacco use.
Results
Initiation rates were 5.9% for nicotine vaping and 8.6% for cannabis vaping, at 12-month follow-up overall. Higher perceived parental knowledge was associated with lower odds of nicotine vaping initiation at 6 months (adj OR: .69; 95% CI: .50-.93) and 12 months (adj OR: .68; 95% CI: .50-.92). Similarly, higher perceived parental knowledge was associated with lower odds of cannabis vaping initiation at 6 months (adj OR: .58; 95% CI: .38-.87) and 12 months (adj OR: .53; 95% CI: .38-.74).
Conclusion
E-cigarette prevention efforts directed at adolescents should incorporate parent engagement strategies as a method of increasing actual and perceived parental knowledge of their child’s location, activities and peer groups.
Keywords
In Brief
The popularity of nicotine and cannabis vaping among youth remains a serious public health concern. Our study found that the risk for initiation of vaping nicotine and vaping cannabis was significantly lower among youth who reported higher rates of parental knowledge. Parental knowledge was a protective factor again initiation of nicotine and cannabis vaping over the course of 12 months.
Introduction
E-cigarettes are the most commonly used nicotine product1,2 and the fastest growing method of marijuana, hash oil and/or tetrahydrocannabinol (THC) use among adolescents in the United States.3-6 From 2017 to 2020, past 30-day e-cigarette use among high school students nearly doubled from 11.7% 7 to 19.6%, 1 and past 30-day vaping of marijuana/THC nearly tripled (4.9%-12.2%).3,4 Conversely, prevalence for combustible methods of both tobacco and marijuana use remain statistically unchanged over this time among high school students. 1 These data signal a consolidation of preference for mode of nicotine and marijuana/THC use among adolescents.
Adolescent nicotine vaping presents a number of public health concerns, including onset of nicotine dependence 8 and initiation of combustible tobacco. 9 Similarly, adolescent marijuana use (via varied formats) is linked to increased risk for cannabis use disorder as well as use of other illicit substances.10,11 Both nicotine12-15 and marijuana/THC16-19 have been linked to impaired brain development (eg, lower brain volumes, different folding patterns and thinning of the cortex, less neural connectivity, lower white matter integrity) and function (eg, excessive neural activity) resulting in poor cognitive development and academic performance among youth. For these reasons, the US Surgeon General 13 and the National Academy of Sciences 12 have each underscored the need to prevent initiation of e-cigarette use during adolescence.
Adolescents who self-report their parents/guardians know their location, activities, and peer groups have significantly lower risk for engaging in negative health behaviors,20-22 including cigarette23-25 and cigar 26 smoking as well as marijuana use.27,28 Prior research has conceptualized knowledge of adolescent’s activities, location, and peer groups as parental monitoring; however, seminal work by Kerr and Stattin29-31 analytically demonstrated that parental knowledge and youth disclosure are a more appropriate conceptualization, with replication studies further validating this conclusion.31,32 While a great deal of literature has discussed and debated the relationship between parenting style, youth disclosure, and substance use,29-31,33 these studies found the strongest predictor of problem behavior among youth was perceived parental knowledge of their activity as it relates to whereabouts and peer groups.29-33 As such, this study focuses on adolescent perception of parental knowledge of their activity in order to parsimoniously examine parental influences on adolescent e-cigarette initiation. In this study, we consider parental knowledge of their child’s location, activities and peer groups after school and when their child goes out.
Despite evidence of parental knowledge as a protective factor for youth tobacco use, little is known about the role of youth perceptions of parental knowledge on vaping of nicotine and marijuana/THC. 34 While common risk factors have been identified for nicotine vaping and combustible tobacco smoking among youth (eg, marketing exposure; sensation seeking; behavioral intentions),35-38 substantive differences in nicotine vaping and combustible tobacco smoking exist by demographic factors (eg, race/ethnicity; sexual identity)1,2 and socio-economic status. 39 As such, we cannot assume prior work on parental knowledge and combustible tobacco use is generalizable to nicotine vaping behaviors and thus there is a need for product-specific research on risk and protective factors for use. Similarly, stark socio-demographic differences between vaping marijuana/THC and other forms of marijuana use (eg, blunts)40-44 among youth have been identified. Given differences in predictors of nicotine vaping and marijuana vaping (relative to combustible methods of nicotine and marijuana use), research is needed to investigate the relationship between parental knowledge of location, activities and peers and adolescent e-cigarette use behaviors with both substances.
This study examines the longitudinal association between parental knowledge of their child’s location, activities, and peer groups as perceived by youth (“perceived parental knowledge”), and initiation of nicotine vaping and marijuana/THC vaping at 6- and 12-month follow-up among a diverse cohort of youth in Texas. We hypothesize that greater perceived parental knowledge will predict lower odds of both nicotine vaping initiation and marijuana/THC vaping initiation at 6- and 12 month follow-up. Understanding the role of perceived parental knowledge on adolescent vaping behaviors holds promise to better inform the design and implementation of e-cigarette interventions, particularly multi-leveled interventions as described by the Substance Abuse and Mental Health Services Administration (SAMHSA). 45 It should be noted, however, that while parental knowledge is an essential protective factor against adolescent tobacco use, parental influences on adolescent substance use are complex and dynamic, encompassing factors such as behavior modeling, effective communication, and parenting style (eg, involvement and supervision). As such, our study is only one component of the multifaceted influences of parents on adolescent substance use behaviors. Additionally, national estimates indicate the median age of e-cigarette initiation is approximately 14.1 year (IQR: 12.1-15.2). 46 Our study will examine a cohort of adolescents with a mean age of 14.3 years at baseline, aligning with the key age for vaping initiation established by national data.
Methods
Study Sample & Study Design
Data were from the Texas Adolescent Tobacco and Marketing Surveillance (TATAMS) system, a population-based surveillance study of e-cigarette use behaviors among Texas youth. Participants were sixth, eighth, and 10th grade students at enrollment (2014–15) and attended school in the 4 largest metropolitan areas of Texas: Austin, Dallas/Fort Worth, Houston, and San Antonio. Participants completed web-based surveys every 6 months and received an electronic gift card for completing each survey. Participants received a $10 Amazon gift card at completion of Wave 1 and Wave 2 surveys and a $25 Amazon gift card at the completion of Wave 3–6 surveys. 47
For this study, we analyzed 3 waves of TATAMS data collected in Spring 2016 (baseline, Wave 4), Fall 2016 (6-month follow-up, Wave 5), and Spring 2017 (12-month follow-up, Wave 6). Baseline for this study reflects the first wave that questions assessing perceived parental knowledge were added to the survey. We conceptualized vaping nicotine initiation and vaping marijuana/THC initiation as discrete behavioral outcomes and thus generated samples of never users at baseline for each product. These procedures resulted in 2 total samples: (1) youth who never vaped nicotine at baseline (n = 1907; weighted sample [N] = 304371) and (2) youth who never vaped marijuana/THC (n = 2212; N=351955) at baseline. Details on sampling procedures are available elsewhere. 47
These samples also reflect exclusion of participants with incomplete data at any of the 3 waves, which ranged from 12.4% among youth who never vaped nicotine to 13.8% among youth who never vaped marijuana/THC. Attrition analyses were conducted to examine bivariate differences on all study variables between included and excluded cases. No statistical differences were observed between included and excluded cases for any of the study variables. As such, data were assumed to be missing completely at random and a complete case analysis was conducted.
The University of Texas Health Science Center (UTHealth) at Houston’s Institutional Review Board approved this study (reference number: HSC-SPH-13-0377). For participating schools, district and principal approval, and where appropriate, school Institutional Review Board approval, were obtained. Parental consent was obtained prior to student enrollment in the study. Student assent was obtained prior to completion of Wave 1 (Fall 2014) survey.
Measures
Initiation of nicotine and marijuana/THC vaping
The outcomes of interest were initiation of (1) nicotine vaping and (2) marijuana/THC vaping. Vaping of nicotine and vaping of marijuana/THC were assessed independently and treated as discrete outcomes. Initiation was defined as the onset of ever use of e-cigarettes to vape each substance. Initiation was measured at Wave 5 (ie, 6-month follow-up, Fall 2016) and Wave 6 (ie, 12-month follow-up, Spring 2017) among adolescents who reported never vaping at Wave 4 (ie, baseline; Spring 2016).
For nicotine vaping, participants were asked the following question: “Have you EVER used an electronic cigarette, vape pen, or e-hookah, even one or two puffs? Remember, marijuana DOES NOT count.” This question was preceded by the following statement: “The following questions pertain to electronic cigarettes with ONLY tobacco or nicotine in them.” For marijuana/THC vaping, participants were asked “Have you EVER smoked marijuana (liquid or wax-based THC) from an electronic cigarette, even one or two puffs?” This question was preceded by the following statement: “Answer the next question only about your experiences using electronic cigarettes with marijuana.” Participants who reported ever vaping nicotine at or by Wave 4 were excluded from analyses examining nicotine vaping initiation. Similarly, participants who reported ever vaping marijuana/THC at or by Wave 4 were excluded from analyses examining marijuana/THC vaping initiation.
Perceived parental knowledge
Consistent with prior literature,29-33 a six-item measure was used to assess parental knowledge of their child’s location, activities, and peer groups, as perceived by youth. Perceived parental knowledge was assessed at baseline. Participants were asked, “After school, my parents know: (1) who I am with; (2) what my plans are; and (3) where I am.” Next, participants were asked, “When I go out, my parents know: (4) who I am with; (5) what my plans are; and (6) where I am.” Possible responses to all six-items ranged from “never” (coded as 1) to “always” (coded as 5). A composite variable was computed 21 to reflect a mean score of the six-items of perceived parental knowledge (range 1–5), with lower scores indicating lower perceived parental knowledge and higher scores indicating higher perceived parental knowledge.29-33 Scale reliability coefficients (ie, alpha scores) were computed for the 6 items to ensure reliability of the parental knowledge construct. For both samples (ie, never nicotine vapers; never cannabis vapers), the scale reliability coefficient was .94. Each item was also considered separately in analyses.
Covariates
This study controlled for sex, race/ethnicity, age, and other tobacco use at baseline. Females served as the referent group. Race/ethnicity was categorically examined with Hispanic/Latino as the referent group as this was the largest category in the dataset; additional racial/ethnic groups included non-Hispanic Whites, non-Hispanic African American, Hispanic/Latino, and non-Hispanic Other. For this study, non-Hispanic Other includes Asian American, American Indian or Alaska Native, Native Hawaiian or Other Pacific Islander, or any other race. Age was analyzed continuously and ranged from 12 to 18 years old. We also controlled for past 30-day use of cigarettes, cigars, smokeless tobacco, and hookah at baseline (Wave 4, Spring 2016). Participants were asked to self-report any use of 1 or more of these tobacco products in the past 30 days.
For analyses of nicotine vaping initiation, we controlled for ever marijuana/THC vaping at baseline. Similarly, for analyses of marijuana/THC vaping, we controlled for ever nicotine vaping at baseline.
Statistical Analysis
Prior to testing study hypotheses, we report weighted descriptive statistics. Next, we conducted bivariate analyses (ie, chi-square, t-tests) to examine correlates for our exposure (ie, perceived parental knowledge) and outcomes (ie, nicotine vaping initiation; marijuana/THC vaping initiation) at baseline as well as at 6- and 12-month follow-up.
Perceived Parental Monitoring and Nicotine Vaping Initiation at 6- and 12-Month (TATAMS, 2016-2017; n=1907; N=304371).
P < .05; **P < .01; ***P<.001.
Note: All covariates were assessed at baseline.
aMean score (1-5) of responses to six-item measurement of perceived parental knowledge: “After school, my parents know (1) who I am with; (2) what my plans are; and (3) where I am.” Next, participants were asked, “When I go out, my parents know: (4) who I am with; (5) what my plans are; and (6) where I am.”
b“Other” is where a response was “Asian, non-Hispanic,” “American Indian/Alaska Native, non-Hispanic,” or “native Hawaiian and other Pacific Islanders, non-Hispanic.”
c Self-reported use of cigarettes, cigars, smokeless tobacco, and/or hookah in the past 30 days.
Perceived Parental Knowledge and Marijuana/THC Vaping Initiation at 6- and 12-Month Follow-Up (TATAMS, 2016-2017; n = 2122; N = 351,955).
*P < .05; **P < .01; ***P<.001.
Note: All covariates were assessed at baseline.
aMean score (1-5) of responses to six-item measurement of perceived parental knowledge: “After school, my parents know (1) who I am with; (2) what my plans are; and (3) where I am.” Next, participants were asked, “When I go out, my parents know: (4) who I am with; (5) what my plans are; and (6) where I am.”
b“Other” is where a response was “Asian, non-Hispanic,” “American Indian/Alaska Native, non-Hispanic,” or “native Hawaiian and other Pacific Islanders, non-Hispanic.”
cSelf-reported use of cigarettes, cigars, smokeless tobacco, and/or hookah in the past 30 days.
To further investigate the role of perceived parental knowledge on vaping nicotine and vaping marijuana/THC, we ran multiple logistic regression models examining the relationship between each of the parental knowledge questions (at baseline) and our outcomes at 6- and 12-month follow-up. These analyses are reported in Supplemental Table A.
All analyses controlled for sex, race/ethnicity, age, other tobacco use, and ever vaping nicotine, were weighted to be representative of the sampling frame, and were conducted using Stata 14.2 (College Station, TX).
Results
Descriptive Statistics
Descriptive Statistics of Never Nicotine Vaping (TATAMS, 2016-2017; n = 1907; N = 304371).
aMean score (1-5) of responses to six-item measurement of perceived parental knowledge: “After school, my parents know (1) who I am with; (2) what my plans are; and (3) where I am.” Next, participants were asked, “When I go out, my parents know: (4) who I am with; (5) what my plans are; and (6) where I am.”
b“Other” is where a response was “Asian, non-Hispanic,” “American Indian/Alaska Native, non-Hispanic,” or “native Hawaiian and other Pacific Islanders, non-Hispanic.”
c Self-reported use of cigarettes, cigars, smokeless tobacco, and/or hookah in the past 30 days.
dComparison of those who did and those who did not initiate e-cigarette use at corresponding Wave.
Descriptive Statistics of Never Marijuana/THC Vaping (TATAMS, 2016–2017; n = 2122; N = 351 955).
aMean score (1-5) of responses to six-item measurement of perceived parental knowledge: “After school, my parents know (1) who I am with; (2) what my plans are; and (3) where I am.” Next, participants were asked, “When I go out, my parents know: (4) who I am with; (5) what my plans are; and (6) where I am.”
b“Other” is where a response was “Asian, non-Hispanic,” “American Indian/Alaska Native, non-Hispanic,” or “native Hawaiian and other Pacific Islanders, non-Hispanic.”
c Self-reported use of cigarettes, cigars, smokeless tobacco, and/or hookah in the past 30 days.
d Comparison of those who did and those who did not initiate e-cigarette use at corresponding Wave.
On a 1-5 scale with lower scores indicating lower perceived parental knowledge, the mean score of perceived parental knowledge was 4.33 (95% CI: 4.31–4.46) for youth who never vaped nicotine at baseline and 4.36 (95% CI: 4.29–4.43) for youth who never vaped marijuana/THC at baseline. Mean perceptions of parental knowledge were lower among youth who initiated nicotine vaping at 6-month (P = .037) and 12-month (P = .016) follow-up, relative to those who did not initiate nicotine vaping. Mean perceptions of parental knowledge were lower among youth who initiated marijuana/THC vaping at 6-month (P = .016) and 12-month (P<.001) follow-up, relative to those who did not initiate marijuana/THC vaping. Further detail on descriptive statistics and bivariate analyses are available in Table 3 and Table 4.
Hypothesis Testing
As seen in Table 1, odds of nicotine vaping initiation at 6-month follow-up decreased by .69 (95% CI: .50–.93) for every unit increase in perceived parental knowledge at baseline, controlling for covariates. Similarly, odds of nicotine vaping initiation at 12-month follow-up decreased by .68 (95% CI: .50–.92) for every unit increase in perceived parental knowledge at baseline, controlling for covariates. Thus, as perceived parental knowledge increases, the odds of nicotine vaping initiation at 6-month follow-up decreased by 44.9% and by 51.5% at 12-month follow-up.
As seen in Table 2, odds of marijuana/THC vaping initiation at 6 month follow-up decreased by .58 (95% CI: .38–.87) for every unit increase in perceived parental knowledge at baseline, controlling for covariates. Similarly, odds of marijuana/THC vaping initiation at 12-month follow-up decreased by .53 (95% CI: .38–.74) for every unit increase in perceived parental knowledge at baseline, controlling for covariates. Thus, as perceived parental knowledge increases, the odds of marijuana/THC vaping initiation at 6-month follow-up decreased by 72.4% and by 78.6% at 12-month follow-up.
Supplemental Analyses
As seen in Supplemental Table A, the 3 items specific to parental knowledge after school predicted lower odds of nicotine and marijuana/THC vaping at 6- and 12-month follow-up. Conversely, the 3 items specific to parental knowledge for “when I go out” were only statistically significant in the models for initiating vaping marijuana/THC not nicotine. Specifically, the 3 items of parental knowledge regarding knowledge of peers and activities after school behavior were more consistently statistically significant than the measures regarding knowledge of peers and activities “when I go out.” Further, the odds ratios for the after school measures were substantially lower than the “when I go out” measures, indicating a stronger protective effect of perceived parental knowledge after school, relative to “when I go out.”
Discussion
This longitudinal study found that young people’s perceptions of a higher level of parental knowledge of their location, activities and peer groups predicted lower risk for initiation of nicotine vaping and marijuana/THC vaping at 6- and 12-month follow-up. This finding is consistent with prior research on perceived parental knowledge as a protective factor for cigarette23-25 and cigar 26 smoking and marijuana use.27,28 While prior research has established a cross-sectional correlation between perceived parental knowledge and adolescent e-cigarette use, 34 this is the first study to find a protective, longitudinal relationship between perceived parental knowledge and adolescent vaping of nicotine. This study further builds on previous research by demonstrating a longitudinal association between perceived parental knowledge and marijuana/THC vaping, which has become an important behavioral phenomenon to understand and address especially among adolescents.
This study has implications for the development and dissemination of public health interventions. Existing e-cigarette prevention programs directly target adolescents and are primarily disseminated in the school setting 48 or through mass media. 49 Our findings, along with prior research on other tobacco products,20-22 suggest the need for e-cigarette prevention efforts to incorporate strategies to directly engage parents/guardians with the intention of increasing actual and perceived parental knowledge of their children’s location, activities and peer groups. Strategies to increase parental knowledge may include addressing parents’ gaps in knowledge of e-cigarettes (eg, device types; vaping of non-nicotine substances; methods of access; harm perceptions) and perceived susceptibility of adolescent e-cigarette use. 13 Another potential strategy is helping parents build skills in learning how to recognize vaping and talking to their teens about vaping. 13 In addition to helping parents build knowledge and skills related to adolescent e-cigarette use, prevention efforts should focus on building parent skills with positive strategies for effective monitoring of and positive communication with their children. The CDC provides a range of recommendations for effective monitoring practices for parents, which include increased emotional connectedness, learning an adolescent’s friends and peer group, and rule setting. 20 Given findings from the current study that indicate perceived parental knowledge may have effects for reducing adolescent nicotine and marijuana/THC vaping for up to 6- and 12-month follow-up, further experimental research is needed on the effectiveness of strategies described here and proposed by the US Surgeon General 13 on increasing parental knowledge of children’s locations, activities, and peer groups, and ultimately on preventing and reducing adolescent e-cigarette use.
The supplemental findings provide a preliminary foundation for future research on parental knowledge in the context of adolescent vaping behavior. By examining each item of the parental knowledge questionnaire, this study found that parental knowledge of adolescent behavior after school appears to be the driving factor in the relationship between parental knowledge and vaping behavior at 6- and 12-month follow-up. This is consistent with prior research showing that unsupervised time after-school is a predictor of substance use and other delinquent behavior50-52 and support the need for greater focus on after-school activities and programs among adolescents as a method of reducing risk for initiation of nicotine and marijuana/THC vaping. These supplemental findings suggest that programs focused on parental engagement should emphasize knowledge of adolescent peers and activities after school as a protective factor against nicotine and cannabis vaping. Given the potential overlap between measures focused on “when I go out” and “afterschool,” future research is needed to further explore the psychometric properties and domains of perceived parental knowledge, which may include the need for greater specificity of knowledge of children’s location, activities and peer groups during specific time periods of a given day or week
Descriptive findings provide important additional context that informs the utility and potential reach of such an approach to e-cigarette prevention. First, the age of our study sample at baseline (mean: 14.3 years) is consistent with the mean age of e-cigarette initiation (14.1 years), 46 according to national data. Second, we found that a total of 6.3% of never nicotine vapers initiated from baseline to 12-month follow-up; a rate consistent with national data. 46 Furthermore, we found that 30.6% of youth who ever vaped nicotine at baseline initiated marijuana/THC vaping by 12-month follow-up. This finding mirrors results from a nationally representative study using data from 2013 to 2015 which found that 26.6% of youth who ever vaped nicotine initiated marijuana/THC vaping at 12-month follow-up. 53 As such, the sample and behaviors observed in this analysis are in line with national trends, increasing the external validity of our presented results.
It should be noted that this study examined perceived parental knowledge of child’s location, activities and peer groups. As such, findings should not be interpreted as a direct examination of parent and guardian behaviors. However, perceptions are highly influential determinant of behaviors. Thus, future research, prevention programs, and health messaging should consider targeting parental knowledge, whether actual or perceived, as a potential protective factor against adolescent nicotine and/or cannabis vaping initiation.
Similar to previous adolescent studies,29-31 mean perceived parental knowledge scores were high (Mean: 4.38 out of 5) for the full sample. This finding indicates that subtle differences in perceived parental knowledge may reduce the protective effects of this construct, resulting in elevated risk for nicotine and/or cannabis vaping initiation. This was observed in the descriptive findings our study, as the mean perceived parental knowledge score for initiators of both nicotine and cannabis vaping were significantly lower than non-initiators (see Tables 3 and 4), corresponding to a relatively large effect sizes for each outcome. As such, nicotine and cannabis prevention interventions would have a meaningful impact on adolescent substance use by generating even minor increases in perceived parental knowledge.
This study has limitations that merit mention. First, data were based on self-report and thus are subject to response bias. Second, the study population was drawn from urban Texas and, as such, findings may not be representative of rural areas or regions with less racial/ethnic diversity. Third, this study was unable to control for other parent-related constructs (eg, behavior modeling, effective communication, and parenting style (eg, involvement and supervision). It is plausible these are confounding factors on the observed relationship, likely influencing perceived parental knowledge and vaping of nicotine/cannabis.
These limitations notwithstanding, key strengths of our study include the large sample size, the longitudinal study design, an ethnically diverse sample—which allows for greater generalizability of our findings, and addressing a specific gap in the current body of research, which advances the body of evidence on e-cigarette use in young people. More research is needed to understand other factors that may influence marijuana/THC vaping and vaping other substances. Future research may test whether parental knowledge is a key mediator of the intervention’s efficacy in regards to preventing e-cigarette use among youth.
What is already known on this topic?
Parental knowledge is a protective factor against initiation of combustible cigarette smoking and combustible marijuana smoking.
What does this article add?
This is the first study to find that perceived parental knowledge is protective against initiation of nicotine and cannabis vaping among adolescents.
What are the implications for health promotion or research?
This longitudinal study indicates that incorporating perceptions of parental knowledge into vaping prevention programs may increase effectiveness.“So What?”
Supplemental Material
sj-pdf-1-ahp-10.1177_08901171211061941 – Supplemental Material for Perceived Parental Knowledge Reduces Risk for Initiation of Nicotine and Cannabis Vaping: A Longitudinal Study of Adolescents
Supplemental Material, sj-pdf-1-ahp-10.1177_08901171211061941 for Perceived Parental Knowledge Reduces Risk for Initiation of Nicotine and Cannabis Vaping: A Longitudinal Study of Adolescents by Dale S. Mantey, Stephanie L. Clendennen, Andrew E. Springer and Melissa B. Harrell in American Journal of Health Promotion
Footnotes
Author Contributions
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Research reported in this paper was supported by grant number [R01-CA239097] from the National Cancer Institute and by the University of Texas Health Science Center at Houston School of Public Health Cancer Education. Additional support was provided by the Career Development Program—National Cancer Institute/NIH Grant—National Cancer Institute/NIH Grant T32/CA057712 (Author: DSM). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health.
Ethical approval
This study was approved by the University of Texas Health Science Center (UTHealth) at Houston’s Institutional Review Board (reference number: HSC-SPH-13-0377).
Supplemental Material
Supplemental material for this article is available online.
References
Supplementary Material
Please find the following supplemental material available below.
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