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The commitment is developed in the form of a contract between a child and a significant adult, constituting the core component of Tobacco-free Duo (T-Duo), a Swedish school-based tobacco prevention program. Secondary analysis of data from a cluster randomized controlled trial. Participants were 586 students in high schools assigned to the intervention arm of T-Duo. At inception, participants attended grade 7 (i.e., age 12\u201313). Only students who were tobacco na\u00efve at baseline for the respective outcome and participated in all follow-ups were included. The exposure was defined as signing a 3-year contract with a significant adult, categorized as \u201cstable contract\u201d (3\u00a0years contract with the same contract partner), \u201cunstable\u201d (signed a contract sometime during follow-up but this was not sustained over time and\/or with the same partner), and \u201cno contract\u201d at all during the intervention period. The primary outcome was having never tried cigarette smoking at the end of grade 9. Exposure and outcomes were self-reported in yearly questionnaires. Of 586 students, 321 (55%) held a stable contract, 204 (35%) an unstable contract, and 61 (10%) did not sign a contract at all. At the end of grade 9 (age 15\u201316), the relative risk (RR) to remain cigarette free was 1.11 (95% CI 1.00\u20131.22) (Number Needed to Treat\u2009=\u200910) among students in any type of contract compared to students that did not write a contract at all. The RRs for remaining tobacco free (secondary outcomes) ranged from 1.07 (0.98\u20131.16) for regular snus use to 1.16 (1.00\u20131.35) for any type of tobacco use. A commitment to remain tobacco free through a child\u2013adult contract seems to exert a preventive effect on the uptake of tobacco use among Swedish adolescents over 3 school years. The current findings apply to a selected sample of both schools and students. Registration: Current Controlled Trials ISRCTN52858080 Date: January 4, 2019, retrospectively registered.<\/jats:p>","DOI":"10.1007\/s11121-023-01598-y","type":"journal-article","created":{"date-parts":[[2023,10,25]],"date-time":"2023-10-25T02:01:26Z","timestamp":1698199286000},"page":"175-192","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Child\u2013Adult Contract for Prevention of Tobacco Use: \u201cAs-Treated\u201d Analysis of a Cluster Randomized Controlled Trial (the TOPAS Study) at 3-Year Follow-Up"],"prefix":"10.1007","volume":"25","author":[{"given":"Dorien Tecla","family":"Beeres","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anni-Maria","family":"Pulkki-Br\u00e4nnstr\u00f6m","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria","family":"Nilsson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria Rosaria","family":"Galanti","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2023,10,25]]},"reference":[{"issue":"8","key":"1598_CR1","doi-asserted-by":"publisher","first-page":"885","DOI":"10.1177\/1403494818799837","volume":"47","author":"A Andersen","year":"2019","unstructured":"Andersen, A., Bast, L. S., Due, P., & Thygesen, L. C. (2019). Evaluation of the smoking intervention X:IT after the second year: A randomized controlled trial. Scandinavian Journal of Public Health, 47(8), 885\u2013889. https:\/\/doi.org\/10.1177\/1403494818799837","journal-title":"Scandinavian Journal of Public Health"},{"issue":"6","key":"1598_CR2","doi-asserted-by":"publisher","first-page":"1900","DOI":"10.1093\/ije\/dyv145","volume":"44","author":"A Andersen","year":"2015","unstructured":"Andersen, A., Kr\u00f8lner, R., Bast, L. S., Thygesen, L. C., & Due, P. (2015). Effects of the X:IT smoking intervention: A school-based cluster randomized trial. International Journal of Epidemiology, 44(6), 1900\u20131908. https:\/\/doi.org\/10.1093\/ije\/dyv145","journal-title":"International Journal of Epidemiology"},{"issue":"4","key":"1598_CR3","doi-asserted-by":"publisher","first-page":"2163","DOI":"10.3390\/ijerph18042163","volume":"18","author":"LS Bast","year":"2021","unstructured":"Bast, L. S., Andersen, S., Glenstrup, S., Damsgaard, M. T., & Andersen, A. (2021). Assessing differences in the implementation of smoke-free contracts\u2014A cross-sectional analysis from the school randomized controlled trial X:IT. International Journal of Environmental Research and Public Health, 18(4), 2163. https:\/\/doi.org\/10.3390\/ijerph18042163","journal-title":"International Journal of Environmental Research and Public Health"},{"key":"1598_CR4","doi-asserted-by":"publisher","unstructured":"Beeres, D., Arn\u00f6, E., Pulkki-Br\u00e4nnstr\u00f6m, A. M., Nilsson, M., & Galanti, M. R. (2022). Evaluation of the Swedish school-based program \u201ctobacco-free DUO\u201d in a cluster randomized controlled trial (TOPAS study). Results at 2-year follow-up. 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Prior to inclusion, all individuals and caregivers of the adolescents were required to give explicit informed consent to data collection, analysis, and reporting of the results. The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. The trial has been registered at Current Controlled Trials ISRCTN52858080, on January 4, 2019, i.e., after the enrollment of the first participant but prior to completed baseline assessment. The study protocol including the pre-registered research questions and planned data analysis has been published elsewhere (Galanti et al., ).\u00a0Anonymized data from the TOPAS study can be accessed via the last author, Maria Rosaria Galanti, upon reasonable request and in line with the data share policy as described in the study protocol. The data share policy includes a formal written agreement with the requesting investigators and agencies to commit themselves to the same confidentiality levels as the leader institution.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethical Approval"}},{"value":"The authors declare no competing interests.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing Interest"}}]}}