Dr. Leas develops and applies methods in computer science and statistics to study a broad range of health topics, including tobacco use, climate change, gun control, distracted driving and mental health. His work has appeared in outlets across medicine and public health, including JAMA Internal Medicine, American Journal of Preventive Medicine, and the American Journal of Public Health.

Professional Education

  • Doctor of Philosophy, University of California San Diego, Public Health: Global Health (2017)
  • Masters of Public Health, University of California Los Angeles, Epidemiology (2013)
  • Bachelors of Arts, University of California San Diego, Sociology: Science and Medicine (2011)

All Publications

  • Standardised cigarette packaging may reduce the implied safety of Natural American Spirit cigarettes. Tobacco control Leas, E. C., Pierce, J. P., Dimofte, C. V., Trinidad, D. R., Strong, D. R. 2018; 27 (e2): e118–e123


    BACKGROUND: Over two-thirds of Natural American Spirit (NAS) smokers believe their cigarettes might be 'less harmful', but toxicological evidence does not support this belief. We assessed whether standardised packaging could reduce the possibility of erroneous inferences of 'safety' drawn from NAS cigarette packaging.METHODS: US adult smokers (n=909) were recruited to a between-subject survey experiment (3 brands*3 packaging/labelling styles) through Amazon Mechanical Turk and rated their perception of whether a randomly assigned cigarette package conveyed that the brand was 'safer' on a three-item scale (Cronbach's alpha=0.92). We assessed whether NAS packs were rated higher on the 'implied safety' scale than two other brands and estimated the effect that plain packaging (ie, all branding replaced with a drab dark brown colour) and Australian-like packaging (ie, all branding replaced with a drab dark brown colour and a graphic image and text on 75% of the pack surface) had on perceptions of the NAS cigarette package.RESULTS: Smokers' ratings of the standard NAS pack on the implied safety scale (mean=4.6; SD=2.9) were 1.9 times (P<0.001) higher than smokers' ratings of a Marlboro Red pack (mean=2.4; SD=2.3) and 1.7 times (P<0.001) higher than smokers' ratings of a Newport Menthol pack (mean=2.7; SD=2.4). These perceptions of implied safety were lower when plain packaging was used (Cohen's d=0.66; P<0.001) and much lower when Australian-like packaging was used (Cohen's d=1.56; P<0.001).CONCLUSION: The results suggest that NAS cigarette packaging conveys that its cigarettes are 'safer' and that such perceptions are lower with standardised packaging, both with and without warning images.

    View details for DOI 10.1136/tobaccocontrol-2017-053940

    View details for PubMedID 29255011

  • Can e-Cigarettes and Pharmaceutical Aids Increase Smoking Cessation and Reduce Cigarette Consumption? Findings from a Nationally Representative Cohort of American Smokers. American journal of epidemiology Benmarhnia, T., Pierce, J. P., Leas, E., White, M. M., Strong, D. R., Noble, M. L., Trinidad, D. R. 2018


    Many smokers believe that electronic nicotine delivery systems (ENDS) and pharmaceutical cessation aids can help them quit smoking or reduce cigarette consumption, but the evidence for e-cigarettes to aid quitting is limited. Examining 3,093 quit attempters in the nationally-representative US Population Assessment of Tobacco and Health (PATH) Study between 2013 and 2015, we evaluated the influence of ENDS and pharmaceutical cessation aids on persistent abstinence (≥30 days) from cigarettes, and reduced cigarette consumption, using Propensity Score Matching to balance comparison groups on potential confounders and multiple imputation to handle missing data. At PATH Wave 2, 25.2% of quit attempters reported using ENDS to quit during the previous year, making it the most popular cessation aid in 2014-15. More quit attempters were persistently cigarette abstinent than persistently tobacco abstinent (15.5±0.8% vs 9.6±0.6%). Using ENDS to quit cigarettes increased the probability of persistent cigarette abstinence at Wave 2 (Risk Difference (RD)=6%; 95% CI: 2%;10%), but using approved pharmaceutical aids did not (varenicline RD=2%; 95% CI: -6%,13%; buproprion RD=4%, 95% CI: -6%, 17%; NRT RD=-3%, 95% CI -8%, 2%). Among quit attempters who relapsed, ENDS did not reduce the average daily cigarette consumption (-0.18 cigarettes per day; 95% CI: -1.87;1.51).

    View details for DOI 10.1093/aje/kwy129

    View details for PubMedID 29955810

  • Effectiveness of Pharmaceutical Smoking Cessation Aids in a Nationally Representative Cohort of American Smokers. Journal of the National Cancer Institute Leas, E. C., Pierce, J. P., Benmarhnia, T., White, M. M., Noble, M. L., Trinidad, D. R., Strong, D. R. 2018; 110 (6): 581–87


    Background: Despite strong efficacy in randomized trials, the population effectiveness of pharmaceutical aids in long-term smoking cessation is lacking, possibly because of confounding (factors that are associated with both pharmaceutical aid use and difficulty quitting). Matching techniques in longitudinal studies can remove this confounding bias.Methods: Using the nationally representative Tobacco Use Supplement to the Current Population Survey (TUS-CPS), we assessed the effectiveness of medications to aid quitting among baseline adult smokers who attempted to quit prior to one year of follow-up in two longitudinal studies: 2002-2003 and 2010-2011. Pharmaceutical aid users and nonusers with complete data (n=2129) were matched using propensity score models with 12 potential confounders (age, sex, race-ethnicity, education, smoking intensity, nicotine dependence, previous quit history, self-efficacy to quit, smoke-free homes, survey year, and cessation aid use). Using matched data sets, logistic regression models were fit to assess whether use of any individual pharmaceutical aid increased the proportion of patients who were abstinent for 30 days or more at follow-up.Results: Propensity score matching markedly improved balance on the potential confounders between the pharmaceutical aid use groups. Using matched samples to provide a balanced comparison, there was no evidence that use of varenicline (adjusted risk difference [aRD] = 0.01, 95% confidence interval [CI] = -0.07 to 0.11), bupropion (aRD = 0.02, 95% CI = -0.04 to 0.09), or nicotine replacement (aRD = 0.01, 95% CI = -0.03 to 0.06) increased the probability of 30 days or more smoking abstinence at one-year follow-up.Conclusions: The lack of effectiveness of pharmaceutical aids in increasing long-term cessation in population samples is not an artifact caused by confounded analyses. A possible explanation is that counseling and support interventions provided in efficacy trials are rarely delivered in the general population.

    View details for DOI 10.1093/jnci/djx240

    View details for PubMedID 29281040

  • Association Between Receptivity to Tobacco Advertising and Progression to Tobacco Use in Youth and Young Adults in the PATH Study JAMA PEDIATRICS Pierce, J. P., Sargent, J. D., Portnoy, D. B., White, M., Noble, M., Kealey, S., Borek, N., Carusi, C., Choi, K., Green, V. R., Kaufman, A. R., Leas, E., Lewis, M., Margolis, K. A., Messer, K., Shi, Y., Silveira, M. L., Snyder, K., Stanton, C. A., Tanski, S. E., Bansal-Travers, M., Trinidad, D., Hyland, A. 2018; 172 (5): 444–51


    Cigarette marketing contributes to initiation of cigarette smoking among young people, which has led to restrictions on use of cigarette advertising. However, little is known about other tobacco advertising and progression to tobacco use in youth and young adults.To investigate whether receptivity to tobacco advertising among youth and young adults is associated with progression (being a susceptible never user or ever user) to use of the product advertised, as well as conventional cigarette smoking.The Population Assessment of Tobacco and Health (PATH) Study at wave 1 (2013-2014) and 1-year follow-up at wave 2 (2014-2015) was conducted in a US population-based sample of never tobacco users aged 12 to 24 years from wave 1 of the PATH Study (N = 10 989). Household interviews using audio computer-assisted self-interviews were conducted.Advertising for conventional cigarettes, electronic cigarettes (e-cigarettes), cigars, and smokeless tobacco products at wave 1.Progression to susceptibility or ever tobacco use at 1-year follow-up in wave 2.Of the 10 989 participants (5410 male [weighted percentage, 48.3%]; 5579 female [weighted percentage, 51.7%]), receptivity to any tobacco advertising at wave 1 was high for those aged 12 to 14 years (44.0%; 95% confidence limit [CL], 42.6%-45.4%) but highest for those aged 18 to 21 years (68.7%; 95% CL, 64.9%-72.2%). e-Cigarette advertising had the highest receptivity among all age groups. For those aged 12 to 17 years, susceptibility to use a product at wave 1 was significantly associated with product use at wave 2 for conventional cigarettes, e-cigarettes, cigars, and smokeless tobacco products. Among committed never users aged 12 to 17 years at wave 1, any receptivity was associated with progression toward use of the product at wave 2 (conventional cigarettes: adjusted odds ratio [AOR], 1.43; 95% CL, 1.23-1.65; e-cigarettes: AOR, 1.62; 95% CL, 1.41-1.85; cigars: AOR, 2.01; 95% CL, 1.62-2.49; and smokeless [males only]: AOR, 1.42; 95% CL, 1.07-1.89) and with use of the product (conventional cigarettes: AOR, 1.54; 95% CL, 1.03-2.32; e-cigarettes: AOR, 1.45; 95% CL, 1.19-1.75; cigars: AOR, 2.07; 95% CL, 1.26-3.40). Compared with those not receptive to any product advertising, receptivity to e-cigarette advertising, but not to cigarette advertising, was independently associated with those aged 12 to 21 years having used a cigarette at wave 2 (AOR, 1.60; 95% CL, 1.08-2.38).Receptivity to tobacco advertising was significantly associated with progression toward use in adolescents. Receptivity was highest for e-cigarette advertising and was associated with trying a cigarette.

    View details for DOI 10.1001/jamapediatrics.2017.5756

    View details for Web of Science ID 000431638900013

    View details for PubMedID 29582078

    View details for PubMedCentralID PMC5875336

  • Online Sales of Marijuana: An Unrecognized Public Health Dilemma AMERICAN JOURNAL OF PREVENTIVE MEDICINE Caputi, T. L., Leas, E. C., Dredze, M., Ayers, J. W. 2018; 54 (5): 719–21

    View details for DOI 10.1016/j.amepre.2018.01.032

    View details for Web of Science ID 000430445300016

    View details for PubMedID 29576446

  • Response. Journal of the National Cancer Institute Pierce, J. P., Leas, E. C., Benmarhnia, T., Strong, D. R. 2018

    View details for DOI 10.1093/jnci/djy026

    View details for PubMedID 29506059

  • The potential influence of regulatory environment for e-cigarettes on the effectiveness of e-cigarettes for smoking cessation: different reasons to temper the conclusions from inadequate data. Nicotine & tobacco research Benmarhnia, T., Leas, E., Hendrickson, E., Trinidad, D., Strong, D., Pierce, J. 2017

    View details for DOI 10.1093/ntr/ntx110

    View details for PubMedID 28541517

  • Receptivity to Tobacco Advertising and Susceptibility to Tobacco Products. Pediatrics Pierce, J. P., Sargent, J. D., White, M. M., Borek, N., Portnoy, D. B., Green, V. R., Kaufman, A. R., Stanton, C. A., Bansal-Travers, M., Strong, D. R., Pearson, J. L., Coleman, B. N., Leas, E., Noble, M. L., Trinidad, D. R., Moran, M. B., Carusi, C., Hyland, A., Messer, K. 2017


    Non-cigarette tobacco marketing is less regulated and may promote cigarette smoking among adolescents. We quantified receptivity to advertising for multiple tobacco products and hypothesized associations with susceptibility to cigarette smoking.Wave 1 of the nationally representative PATH (Population Assessment of Tobacco and Health) study interviewed 10 751 adolescents who had never used tobacco. A stratified random selection of 5 advertisements for each of cigarettes, e-cigarettes, smokeless products, and cigars were shown from 959 recent tobacco advertisements. Aided recall was classified as low receptivity, and image-liking or favorite ad as higher receptivity. The main dependent variable was susceptibility to cigarette smoking.Among US youth, 41% of 12 to 13 year olds and half of older adolescents were receptive to at least 1 tobacco advertisement. Across each age group, receptivity to advertising was highest for e-cigarettes (28%-33%) followed by cigarettes (22%-25%), smokeless tobacco (15%-21%), and cigars (8%-13%). E-cigarette ads shown on television had the highest recall. Among cigarette-susceptible adolescents, receptivity to e-cigarette advertising (39.7%; 95% confidence interval [CI]: 37.9%-41.6%) was higher than for cigarette advertising (31.7%; 95% CI: 29.9%-33.6%). Receptivity to advertising for each tobacco product was associated with increased susceptibility to cigarette smoking, with no significant difference across products (similar odds for both cigarette and e-cigarette advertising; adjusted odds ratio = 1.22; 95% CI: 1.09-1.37).A large proportion of US adolescent never tobacco users are receptive to tobacco advertising, with television advertising for e-cigarettes having the highest recall. Receptivity to advertising for each non-cigarette tobacco product was associated with susceptibility to smoke cigarettes.

    View details for DOI 10.1542/peds.2016-3353

    View details for PubMedID 28562266

    View details for PubMedCentralID PMC5470502

  • The Charlie Sheen Effect on Rapid In-home Human Immunodeficiency Virus Test Sales. Prevention science Allem, J., Leas, E. C., Caputi, T. L., Dredze, M., Althouse, B. M., Noar, S. M., Ayers, J. W. 2017


    One in eight of the 1.2 million Americans living with human immunodeficiency virus (HIV) are unaware of their positive status, and untested individuals are responsible for most new infections. As a result, testing is the most cost-effective HIV prevention strategy and must be accelerated when opportunities are presented. Web searches for HIV spiked around actor Charlie Sheen's HIV-positive disclosure. However, it is unknown whether Sheen's disclosure impacted offline behaviors like HIV testing. The goal of this study was to determine if Sheen's HIV disclosure was a record-setting HIV prevention event and determine if Web searches presage increases in testing allowing for rapid detection and reaction in the future. Sales of OraQuick rapid in-home HIV test kits in the USA were monitored weekly from April 12, 2014, to April 16, 2016, alongside Web searches including the terms "test," "tests," or "testing" and "HIV" as accessed from Google Trends. Changes in OraQuick sales around Sheen's disclosure and prediction models using Web searches were assessed. OraQuick sales rose 95% (95% CI, 75-117; p < 0.001) of the week of Sheen's disclosure and remained elevated for 4 more weeks (p < 0.05). In total, there were 8225 more sales than expected around Sheen's disclosure, surpassing World AIDS Day by a factor of about 7. Moreover, Web searches mirrored OraQuick sales trends (r = 0.79), demonstrating their ability to presage increases in testing. The "Charlie Sheen effect" represents an important opportunity for a public health response, and in the future, Web searches can be used to detect and act on more opportunities to foster prevention behaviors.

    View details for DOI 10.1007/s11121-017-0792-2

    View details for PubMedID 28516308

  • Susceptibility to tobacco product use among youth in wave 1 of the population Assessment of tobacco and health (PATH) study. Preventive medicine Trinidad, D. R., Pierce, J. P., Sargent, J. D., White, M. M., Strong, D. R., Portnoy, D. B., Green, V. R., Stanton, C. A., Choi, K., Bansal-Travers, M., Shi, Y., Pearson, J. L., Kaufman, A. R., Borek, N., Coleman, B. N., Hyland, A., Carusi, C., Kealey, S., Leas, E., Noble, M. L., Messer, K. 2017; 101: 8-14


    The purpose of this study was to investigate susceptibility and ever use of tobacco products among adolescents and young adults in the US. Cross-sectional analysis of Wave 1(2013-2014) adolescent (12-17year-olds; n=13,651) and young adult (18-24year-olds; n=9112) data from the nationally-representative Population Assessment of Tobacco and Health (PATH) Study was conducted. At 12years, 5% were ever tobacco users and 36% were susceptible to use. Seventy percent were susceptible at age 17years, and the same proportion were ever users at age 22years. Susceptibility levels were comparable for cigarettes and e-cigarette (28.6% and 27.4%, respectively), followed by hookah (22.0%), pipes (17.5%), cigars (15.2%), and smokeless tobacco (9.7%). Non-Hispanic (NH) Black (Adjusted Odds Ratio [ORadj]=1.36; 95% Confidence Limit [CL], 1.18-1.56) and Hispanic (ORadj=1.34: 95% CL,1.19-1.49) adolescent never- users were more likely to be susceptible to future use of a tobacco product than NH Whites. Susceptibility was higher with age (15-17yrs. vs 12-14yrs.: ORadj=1.69; 95% CL, 1.55-1.85) and parental education (college graduates vs less than HS education: ORadj=1.22, 95% CL, 1.08-1.39). Compared to exclusive users of hookah, cigars, or smokeless products, larger proportions of exclusive e-cigarette ever users were also susceptible to cigarette use. Among adolescents, lower levels of ever use of tobacco products are often counterbalanced by higher levels of susceptibility for future use, which may suggest delayed initiation in some groups. Ever users of a given tobacco product were more susceptible to use other tobacco products, putting them at risk for future multiple tobacco product use.

    View details for DOI 10.1016/j.ypmed.2017.05.010

    View details for PubMedID 28526392

    View details for PubMedCentralID PMC5537073

  • Postdiagnosis social networks and breast cancer mortality in the After Breast Cancer Pooling Project. Cancer Kroenke, C. H., Michael, Y. L., Poole, E. M., Kwan, M. L., Nechuta, S., Leas, E., Caan, B. J., Pierce, J., Shu, X., Zheng, Y., Chen, W. Y. 2017; 123 (7): 1228-1237


    Large social networks have been associated with better overall survival, though not consistently with breast cancer (BC)-specific outcomes. This study evaluated associations of postdiagnosis social networks and BC outcomes in a large cohort.Women from the After Breast Cancer Pooling Project (n = 9267) provided data on social networks within approximately 2 years of their diagnosis. A social network index was derived from information about the presence of a spouse/partner, religious ties, community ties, friendship ties, and numbers of living first-degree relatives. Cox models were used to evaluate associations, and a meta-analysis was used to determine whether effect estimates differed by cohort. Stratification by demographic, social, tumor, and treatment factors was performed.There were 1448 recurrences and 1521 deaths (990 due to BC). Associations were similar in 3 of 4 cohorts. After covariate adjustments, socially isolated women (small networks) had higher risks of recurrence (hazard ratio [HR], 1.43; 95% confidence interval [CI], 1.15-1.77), BC-specific mortality (HR, 1.64; 95% CI, 1.33-2.03), and total mortality (HR, 1.69; 95% CI, 1.43-1.99) than socially integrated women; associations were stronger in those with stage I/II cancer. In the fourth cohort, there were no significant associations with BC-specific outcomes. A lack of a spouse/partner (P = .02) and community ties (P = .04) predicted higher BC-specific mortality in older white women but not in other women. However, a lack of relatives (P = .02) and friendship ties (P = .01) predicted higher BC-specific mortality in nonwhite women only.In a large pooled cohort, larger social networks were associated with better BC-specific and overall survival. Clinicians should assess social network information as a marker of prognosis because critical supports may differ with sociodemographic factors. Cancer 2017;123:1228-1237. © 2016 American Cancer Society.

    View details for DOI 10.1002/cncr.30440

    View details for PubMedID 27943274

    View details for PubMedCentralID PMC5360517

  • Pre-adolescent Receptivity to Tobacco Marketing and Its Relationship to Acquiring Friends Who Smoke and Cigarette Smoking Initiation. Annals of behavioral medicine : a publication of the Society of Behavioral Medicine Strong, D. R., Messer, K., Hartman, S. J., Nodora, J., Vera, L., White, M. M., Leas, E., Pharris-Ciurej, N., Borek, N., Pierce, J. P. 2017


    This study extends research on receptivity to tobacco marketing over a key developmental period for cigarette smoking experimentation.The purpose of this study was to understand the effect of receptivity to tobacco marketing and exposure to friends who smoke on smoking experimentation.Participants were 10 to 13 years old who had never tried cigarettes (n = 878), interviewed six times at 8-month intervals.At baseline, 25% percent of the 10 and 11 years old in the sample of never smokers were receptive to tobacco marketing, while less than 5% had friends who smoked. Having a friend who smoked at study baseline and acquiring such friends for the first time during the study were the strongest predictors of smoking experimentation. Initial receptivity to tobacco marketing increased the risk of smoking experimentation independently of having friends who smoke at baseline or acquiring friends who smoke throughout the study period.The high level of receptivity observed even among 10 and 11 years old and its robust relationship with cigarette smoking experimentation independent of the significant risk associated with having friends who smoke suggests that successful prevention of receptivity may require intervention at an early age.

    View details for DOI 10.1007/s12160-017-9896-y

    View details for PubMedID 28255935

  • Which cigarettes do Americans think are safer? A population-based analysis with wave 1 of the PATH study TOBACCO CONTROL Leas, E. C., Ayers, J. W., Strong, D. R., Pierce, J. P. 2017; 26 (E1): E59-E60
  • Why do people use electronic nicotine delivery systems (electronic cigarettes)? A content analysis of Twitter, 2012-2015 PLOS ONE Ayers, J. W., Leas, E. C., Allem, J., Benton, A., Dredze, M., Althouse, B. M., Cruz, T. B., Unger, J. B. 2017; 12 (3)


    The reasons for using electronic nicotine delivery systems (ENDS) are poorly understood and are primarily documented by expensive cross-sectional surveys that use preconceived close-ended response options rather than allowing respondents to use their own words. We passively identify the reasons for using ENDS longitudinally from a content analysis of public postings on Twitter. All English language public tweets including several ENDS terms (e.g., "e-cigarette" or "vape") were captured from the Twitter data stream during 2012 and 2015. After excluding spam, advertisements, and retweets, posts indicating a rationale for vaping were retained. The specific reasons for vaping were then inferred based on a supervised content analysis using annotators from Amazon's Mechanical Turk. During 2012 quitting combustibles was the most cited reason for using ENDS with 43% (95%CI 39-48) of all reason-related tweets cited quitting combustibles, e.g., "I couldn't quit till I tried ecigs," eclipsing the second most cited reason by more than double. Other frequently cited reasons in 2012 included ENDS's social image (21%; 95%CI 18-25), use indoors (14%; 95%CI 11-17), flavors (14%; 95%CI 11-17), safety relative to combustibles (9%; 95%CI 7-11), cost (3%; 95%CI 2-5) and favorable odor (2%; 95%CI 1-3). By 2015 the reasons for using ENDS cited on Twitter had shifted. Both quitting combustibles and use indoors significantly declined in mentions to 29% (95%CI 24-33) and 12% (95%CI 9-16), respectively. At the same time, social image increased to 37% (95%CI 32-43) and lack of odor increased to 5% (95%CI 2-5), the former leading all cited reasons in 2015. Our data suggest the reasons people vape are shifting away from cessation and toward social image. The data also show how the ENDS market is responsive to a changing policy landscape. For instance, smoking indoors was less frequently cited in 2015 as indoor smoking restrictions became more common. Because the data and analytic approach are scalable, adoption of our strategies in the field can inform follow-up survey-based surveillance (so the right questions are asked), interventions, and policies for ENDS.

    View details for DOI 10.1371/journal.pone.0170702

    View details for Web of Science ID 000395983500007

    View details for PubMedID 28248987

    View details for PubMedCentralID PMC5331961

  • Can a selfie promote public engagement with skin cancer? Preventive medicine Noar, S. M., Leas, E., Althouse, B. M., Dredze, M., Kelley, D., Ayers, J. W. 2017


    Social media may provide new opportunities to promote skin cancer prevention, but research to understand this potential is needed. In April of 2015, Kentucky native Tawny Willoughby (TW) shared a graphic skin cancer selfie on Facebook that subsequently went viral. We examined the volume of comments and shares of her original Facebook post; news volume of skin cancer from Google News; and search volume for skin cancer Google queries. We compared these latter metrics after TWs announcement against expected volumes based on forecasts of historical trends. TW's skin cancer selfie went viral on May 11, 2015 after the social media post had been shared approximately 50,000 times. All search queries for skin cancer increased 162% (95% CI 102 to 320) and 155% (95% CI 107 to 353) on May 13th and 14th, when news about TW's skin cancer selfie was at its peak, and remained higher through May 17th. Google searches about skin cancer prevention and tanning were also significantly higher than expected volumes. In practical terms, searches reached near-record levels - i.e., May 13th, 14th and 15th were respectively the 6th, 8th, and 40th most searched days for skin cancer since January 1, 2004 when Google began tracking searches. We conclude that an ordinary person's social media post caught the public's imagination and led to significant increases in public engagement with skin cancer prevention. Digital surveillance methods can rapidly detect these events in near real time, allowing public health practitioners to engage and potentially elevate positive effects.

    View details for DOI 10.1016/j.ypmed.2017.10.038

    View details for PubMedID 29109014

  • They're heating up: Internet search query trends reveal significant public interest in heat-not-burn tobacco products. PloS one Caputi, T. L., Leas, E., Dredze, M., Cohen, J. E., Ayers, J. W. 2017; 12 (10): e0185735


    Heat-not-burn tobacco products, battery powered devices that heat leaf tobacco to approximately 500 degrees Fahrenheit to produce an inhalable aerosol, are being introduced in markets around the world. Japan, where manufacturers have marketed several heat-not-burn brands since 2014, has been the focal national test market, with the intention of developing global marketing strategies. We used Google search query data to estimate, for the first time, the scale and growth potential of heat-not-burn tobacco products. Average monthly searches for heat-not-burn products rose 1,426% (95%CI: 746,3574) between their first (2015) and second (2016) complete years on the market and an additional 100% (95%CI: 60, 173) between the products second (2016) and third years on the market (Jan-Sep 2017). There are now between 5.9 and 7.5 million heat-not-burn related Google searches in Japan each month based on September 2017 estimates. Moreover, forecasts relying on the historical trends suggest heat-not-burn searches will increase an additional 32% (95%CI: -4 to 79) during 2018, compared to current estimates for 2017 (Jan-Sep), with continued growth thereafter expected. Contrasting heat-not-burn's rise in Japan to electronic cigarettes' rise in the United States we find searches for heat-not-burn eclipsed electronic cigarette searches during April 2016. Moreover, the change in average monthly queries for heat-not-burn in Japan between 2015 and 2017 was 399 (95% CI: 184, 1490) times larger than the change in average monthly queries for electronic cigarettes in the Unites States over the same time period, increasing by 2,956% (95% CI: 1729, 7304) compared to only 7% (95% CI: 3,13). Our findings are a clarion call for tobacco control leaders to ready themselves as heat-not-burn tobacco products will likely garner substantial interest as they are introduced into new markets. Public health practitioners should expand heat-not-burn tobacco product surveillance, adjust existing tobacco control strategies to account for heat-not-burn tobacco products, and preemptively study the health risks/benefits, popular perceptions, and health messaging around heat-not-burn tobacco products.

    View details for DOI 10.1371/journal.pone.0185735

    View details for PubMedID 29020019

  • Internet Searches for Suicide Following the Release of 13 Reasons Why. JAMA internal medicine Ayers, J. W., Althouse, B. M., Leas, E. C., Dredze, M., Allem, J. P. 2017

    View details for DOI 10.1001/jamainternmed.2017.3333

    View details for PubMedID 28759671

  • Pokemon GO-A New Distraction for Drivers and Pedestrians JAMA INTERNAL MEDICINE Ayers, J. W., Leas, E. C., Dredze, M., Allem, J., Grabowski, J. G., Hill, L. 2016; 176 (12): 1865-1866
  • Big Data Sensors of Organic Advocacy: The Case of Leonardo DiCaprio and Climate Change PLOS ONE Leas, E. C., Althouse, B. M., Dredze, M., Obradovich, N., Fowler, J. H., Noar, S. M., Allem, J., Ayers, J. W. 2016; 11 (8)


    The strategies that experts have used to share information about social causes have historically been top-down, meaning the most influential messages are believed to come from planned events and campaigns. However, more people are independently engaging with social causes today than ever before, in part because online platforms allow them to instantaneously seek, create, and share information. In some cases this "organic advocacy" may rival or even eclipse top-down strategies. Big data analytics make it possible to rapidly detect public engagement with social causes by analyzing the same platforms from which organic advocacy spreads. To demonstrate this claim we evaluated how Leonardo DiCaprio's 2016 Oscar acceptance speech citing climate change motivated global English language news (Bloomberg Terminal news archives), social media (Twitter postings) and information seeking (Google searches) about climate change. Despite an insignificant increase in traditional news coverage (54%; 95%CI: -144 to 247), tweets including the terms "climate change" or "global warming" reached record highs, increasing 636% (95%CI: 573-699) with more than 250,000 tweets the day DiCaprio spoke. In practical terms the "DiCaprio effect" surpassed the daily average effect of the 2015 Conference of the Parties (COP) and the Earth Day effect by a factor of 3.2 and 5.3, respectively. At the same time, Google searches for "climate change" or "global warming" increased 261% (95%CI, 186-335) and 210% (95%CI 149-272) the day DiCaprio spoke and remained higher for 4 more days, representing 104,190 and 216,490 searches. This increase was 3.8 and 4.3 times larger than the increases observed during COP's daily average or on Earth Day. Searches were closely linked to content from Dicaprio's speech (e.g., "hottest year"), as unmentioned content did not have search increases (e.g., "electric car"). Because these data are freely available in real time our analytical strategy provides substantial lead time for experts to detect and participate in organic advocacy while an issue is salient. Our study demonstrates new opportunities to detect and aid agents of change and advances our understanding of communication in the 21st century media landscape.

    View details for DOI 10.1371/journal.pone.0159885

    View details for Web of Science ID 000381110700017

    View details for PubMedID 27482907

    View details for PubMedCentralID PMC4970768

  • US adult smokers' perceptions of Australia's cigarette warning labels: variance by warning content and consistency across socio-demographic sub-segments. Tobacco control Leas, E. C., Pierce, J. P., Dimofte, C. V., Villaseñor, A., Strong, D. R. 2016

    View details for DOI 10.1136/tobaccocontrol-2016-053006

    View details for PubMedID 27343227

    View details for PubMedCentralID PMC5309205

  • Revisiting the Rise of Electronic Nicotine Delivery Systems Using Search Query Surveillance AMERICAN JOURNAL OF PREVENTIVE MEDICINE Ayers, J. W., Althouse, B. M., Allem, J., Leas, E. C., Dredze, M., Williams, R. S. 2016; 50 (6): E173-E181


    Public perceptions of electronic nicotine delivery systems (ENDS) remain poorly understood because surveys are too costly to regularly implement and, when implemented, there are long delays between data collection and dissemination. Search query surveillance has bridged some of these gaps. Herein, ENDS' popularity in the U.S. is reassessed using Google searches.ENDS searches originating in the U.S. from January 2009 through January 2015 were disaggregated by terms focused on e-cigarette (e.g., e-cig) versus vaping (e.g., vapers); their geolocation (e.g., state); the aggregate tobacco control measures corresponding to their geolocation (e.g., clean indoor air laws); and by terms that indicated the searcher's potential interest (e.g., buy e-cigs likely indicates shopping)-all analyzed in 2015.ENDS searches are rapidly increasing in the U.S., with 8,498,000 searches during 2014 alone. Increasingly, searches are shifting from e-cigarette- to vaping-focused terms, especially in coastal states and states where anti-smoking norms are stronger. For example, nationally, e-cigarette searches declined 9% (95% CI=1%, 16%) during 2014 compared with 2013, whereas vaping searches increased 136% (95% CI=97%, 186%), even surpassing e-cigarette searches. Additionally, the percentage of ENDS searches related to shopping (e.g., vape shop) nearly doubled in 2014, whereas searches related to health concerns (e.g., vaping risks) or cessation (e.g., quit smoking with e-cigs) were rare and declined in 2014.ENDS popularity is rapidly growing and evolving. These findings could inform survey questionnaire development for follow-up investigation and immediately guide policy debates about how the public perceives the health risks or cessation benefits of ENDS.

    View details for DOI 10.1016/j.amepre.2015.12.008

    View details for Web of Science ID 000376509900002

    View details for PubMedID 26876772

    View details for PubMedCentralID PMC5422030

  • News and Internet Searches About Human Immunodeficiency Virus After Charlie Sheen's Disclosure JAMA INTERNAL MEDICINE Ayers, J. W., Althouse, B. M., Dredze, M., Leas, E. C., Noar, S. M. 2016; 176 (4): 552-554
  • Leveraging Big Data to Improve Health Awareness Campaigns: A Novel Evaluation of the Great American Smokeout. JMIR public health and surveillance Ayers, J. W., Westmaas, J. L., Leas, E. C., Benton, A., Chen, Y., Dredze, M., Althouse, B. M. 2016; 2 (1)


    Awareness campaigns are ubiquitous, but little is known about their potential effectiveness because traditional evaluations are often unfeasible. For 40 years, the "Great American Smokeout" (GASO) has encouraged media coverage and popular engagement with smoking cessation on the third Thursday of November as the nation's longest running awareness campaign.We proposed a novel evaluation framework for assessing awareness campaigns using the GASO as a case study by observing cessation-related news reports and Twitter postings, and cessation-related help seeking via Google, Wikipedia, and government-sponsored quitlines.Time trends (2009-2014) were analyzed using a quasi-experimental design to isolate spikes during the GASO by comparing observed outcomes on the GASO day with the simulated counterfactual had the GASO not occurred.Cessation-related news typically increased by 61% (95% CI 35-87) and tweets by 13% (95% CI -21 to 48) during the GASO compared with what was expected had the GASO not occurred. Cessation-related Google searches increased by 25% (95% CI 10-40), Wikipedia page visits by 22% (95% CI -26 to 67), and quitline calls by 42% (95% CI 19-64). Cessation-related news media positively coincided with cessation tweets, Internet searches, and Wikipedia visits; for example, a 50% increase in news for any year predicted a 28% (95% CI -2 to 59) increase in tweets for the same year. Increases on the day of the GASO rivaled about two-thirds of a typical New Year's Day-the day that is assumed to see the greatest increases in cessation-related activity. In practical terms, there were about 61,000 more instances of help seeking on Google, Wikipedia, or quitlines on GASO each year than would normally be expected.These findings provide actionable intelligence to improve the GASO and model how to rapidly, cost-effectively, and efficiently evaluate hundreds of awareness campaigns, nearly all for the first time.

    View details for DOI 10.2196/publichealth.5304

    View details for PubMedID 27227151

    View details for PubMedCentralID PMC4869240

  • Gender differences influence overweight smokers' experimentation with electronic nicotine delivery systems ADDICTIVE BEHAVIORS Strong, D. R., Myers, M., Linke, S., Leas, E., Hofstetter, R., Edland, S., Al-Delaimy, W. K. 2015; 49: 20-25


    Overweight and obese tobacco users possess increased risk of cancer, diabetes, heart disease and chronic tobacco-related disease. Efforts to prevent tobacco-related health risk in this comorbid population would be informed by better understanding and monitoring of trends in the concurrent use of electronic nicotine delivery systems (ENDS) among smokers in the US marketplace.The California Longitudinal Smokers Study (CLSS) established a cohort of current cigarette smokers in 2011 who were surveyed for tobacco use and health behavior at baseline and again in 2012 at follow-up.We observed a large increase in reported experimentation with ENDS. As hypothesized, overweight or obese smokers were more likely to report experimentation with ENDS, an increase that was also observed among women. Experimentation with ENDS was not associated with a reduction in use of cigarettes or a decrease in cigarette dependence in this high risk population of smokers.Continued surveillance of this vulnerable population is needed to better understand how experimentation with new ENDS products may impact health, facilitate switching to non-combustible tobacco or facilitate persistent cigarette dependence.

    View details for DOI 10.1016/j.addbeh.2015.05.003

    View details for Web of Science ID 000358466200004

    View details for PubMedID 26036665

    View details for PubMedCentralID PMC4478105

  • Smokers who report smoking but do not consider themselves smokers: a phenomenon in need of further attention TOBACCO CONTROL Leas, E. C., Zablocki, R. W., Edland, S. D., Al-Delaimy, W. K. 2015; 24 (4): 400-403


    Heightened stigma surrounding the action of smoking may decrease the likelihood that individuals who engage in smoking identify with the label 'smoker'. Non-identifying smokers (NIS) may undermine accurate smoking prevalence estimates and can be overlooked by tobacco control efforts.We sought to characterise NIS in a cross-sectional study using a sample representative of the population of adults (>18 years) in California who reported smoking at least 100 cigarettes in their lifetime, smoking at least some days and at least once in the last 30 days (n=1698). Individuals were considered NIS if they met the above criteria and answered 'no' when asked if they 'considered themselves a smoker'.We estimate that 395 928 (SD=54 126) NIS were living in California in 2011 (a prevalence of 12.3% of all smokers in California). The odds of being NIS were higher among non-daily smokers who were previously daily smokers (adjusted OR (AOR)=7.63, 95% CI 2.67 to 21.8) or were never previously daily smokers (AOR=7.14, CI 2.78 to 18.3) compared with daily smokers. The odds of being an NIS were also higher among those who did not believe they were addicted to cigarettes (AOR=3.84, CI 1.68 to 9.22), were older than 65 years (vs less than 45 years) (AOR=3.35, CI 1.16 to 9.75) or were from ethnic minorities including Black and Asian (vs non-Hispanic white) (AOR=3.16, CI 1.19 to 8.49).Smoking surveillance should restructure selection criteria to more accurately account for NIS in areas with high stigma toward smokers. Targeted interventions may be needed for NIS including educating healthcare providers to enquire more deeply into smoking habits.

    View details for DOI 10.1136/tobaccocontrol-2013-051400

    View details for Web of Science ID 000356604100021

    View details for PubMedID 24500273

  • E-Cigarette Use in the Past and Quitting Behavior in the Future: A Population-Based Study AMERICAN JOURNAL OF PUBLIC HEALTH Al-Delaimy, W. K., Myers, M. G., Leas, E. C., Strong, D. R., Hofstetter, C. R. 2015; 105 (6): 1213-1219


    We examined whether smokers who used e-cigarettes are more likely to quit after 1 year than smokers who had never used e-cigarettes.We surveyed California smokers (n = 1000) at 2 time points 1 year apart. We conducted logistic regression analyses to determine whether history of e-cigarette use at baseline predicted quitting behavior at follow-up, adjusting for demographics and smoking behavior at baseline. We limited analyses to smokers who reported consistent e-cigarette behavior at baseline and follow-up.Compared with smokers who never used e-cigarettes, smokers who ever used e-cigarettes were significantly less likely to decrease cigarette consumption (odds ratio [OR] = 0.51; 95% confidence interval [CI] = 0.30, 0.87), and significantly less likely to quit for 30 days or more at follow-up (OR = 0.41; 95% CI = 0.18, 0.93). Ever-users of e-cigarettes were more likely to report a quit attempt, although this was not statistically significant (OR = 1.15; 95% CI = 0.67, 1.97).Smokers who have used e-cigarettes may be at increased risk for not being able to quit smoking. These findings, which need to be confirmed by longer-term cohort studies, have important policy and regulation implications regarding the use of e-cigarettes among smokers.

    View details for DOI 10.2105/AJPH.2014.302482

    View details for Web of Science ID 000360466800039

    View details for PubMedID 25880947

    View details for PubMedCentralID PMC4431097

  • Recall of Anti-Tobacco Advertisements and Effects on Quitting Behavior: Results From the California Smokers Cohort AMERICAN JOURNAL OF PUBLIC HEALTH Leas, E. C., Myers, M. G., Strong, D. R., Hofstetter, C. R., Al-Delaimy, W. K. 2015; 105 (2): E90-E97


    We assessed whether an anti-tobacco television advertisement called "Stages," which depicted a woman giving a brief emotional narrative of her experiences with tobacco use, would be recalled more often and have a greater effect on smoking cessation than 3 other advertisements with different intended themes.Our data were derived from a sample of 2596 California adult smokers. We used multivariable log-binomial and modified Poisson regression models to calculate respondents' probability of quitting as a result of advertisement recall.More respondents recalled the "Stages" ad (58.5%) than the 3 other ads (23.1%, 23.4%, and 25.6%; P<.001). Respondents who recalled "Stages" at baseline had a higher probability than those who did not recall the ad of making a quit attempt between baseline and follow-up (adjusted risk ratio [RR]=1.18; 95% confidence interval [CI]=1.03, 1.34) and a higher probability of being in a period of smoking abstinence for at least a month at follow-up (adjusted RR=1.55; 95% CI=1.02, 2.37).Anti-tobacco television advertisements that depict visceral and personal messages may be recalled by a larger percentage of smokers and may have a greater impact on smoking cessation than other types of advertisements.

    View details for DOI 10.2105/AJPH.2014.302249

    View details for Web of Science ID 000351922500018

    View details for PubMedID 25521871

    View details for PubMedCentralID PMC4318324

  • Is Gray Water the Key to Unlocking Water for Resource-Poor Areas of the Middle East, North Africa, and Other Arid Regions of the World? AMBIO Leas, E. C., Dare, A., Al-Delaimy, W. K. 2014; 43 (6): 707-717


    Support for the use of treated gray water as an alternative water resource in the Middle East and North Africa is high, especially given the lack of religious restrictions against its use, but several obstacles have kept application of treated gray water near 1 % in some areas. The largest of obstacles include the cost of treatment and the ambiguity surrounding the health safety of gray water and treated gray water. This paper aims to provide an overview of current gray water practices globally, with specific focus on household-level gray water practices in the Middle East and North Africa region, and highlight the need for cost reduction strategies and epidemiological evidence on the use of household-level gray water and treated gray water. Such actions are likely to increase the application of treated gray water in water-deprived areas of the Middle East and North Africa.

    View details for DOI 10.1007/s13280-013-0462-y

    View details for Web of Science ID 000342205400001

    View details for PubMedID 24165868

    View details for PubMedCentralID PMC4165838