This cross-sectional study investigates whether the use of nicotine pouches is associated with poorer mental and physical well-being and increased school absence among Danish adolescents.

The study population comprises 13-18-year-old students from public schools in Aarhus Municipality, Denmark, who completed two school-based questionnaires between September 2020 and June 2022: (1) the Aarhus Municipality Questionnaire (AMQ), including items on nicotine use, and (2) the Danish National Well-being Questionnaire (DNWQ), a 40-item instrument assessing different domains of school-related well-being. Questionnaire data are linked at the individual level to national administrative registers via the Danish Civil Registration System.

Exposure is defined as current use of nicotine pouches based on AMQ responses. Adolescents who report using "snus" (slang for nicotine pouches) "not every day, but every week" or "every day" are classified as nicotine pouch users. Non-exposed adolescents are those who report no use or less than weekly use; individuals who choose "I do not wish to answer" are categorized as "undisclosed" and excluded from primary analyses.

The primary outcomes are: (1) a composite mental and physical well-being score derived from 10 DNWQ items (Likert scales recoded to a 1-5 range, summed to a total score from 10 to 50) and (2) days of school absence (overall, and by illegal vs. sickness-related absence) obtained from national education registers. Secondary outcomes include item-level response patterns for the 10 DNWQ items and subgroup analyses of the association between nicotine pouch use and well-being across strata of socioeconomic status, age, sex, origin, and mental illness in the adolescent or their caregivers.

Covariates are drawn from questionnaires and national registers and include age, sex, e-cigarette and cigarette use, family structure, household education, household income, immigration status, and psychiatric diagnoses in the adolescent and household providers.

Descriptive statistics will compare baseline characteristics between nicotine pouch users and non-users. Primary analyses will apply linear mixed-effects models for the continuous well-being score and generalized linear mixed models with log link (Poisson or negative binomial) for counts of school absence, with and without adjustment for key confounders (age, sex, household education, household income, origin). Missing covariate data will be addressed using multiple imputation by chained equations under a missing-at-random assumption. Effect modification will be explored by stratified analyses and interaction terms.

The study will provide novel, population-based evidence on the potential mental, physical, and educational consequences of nicotine pouch use among adolescents, informing clinicians, public health professionals, and policymaker

Inclusion Criteria:

• Answered all questions regarding usage of nicotine (AMQ) AND
• Answered questions regarding mental and physical well-being in DNWQ AND/OR
• Available data on school absence

Exclusion Criteria:

• Student in a special needs class or reception class for newcomers

Danish adolescents, age 13-18 years, from Aarhus municipality between September 2020 to June 2022

Data has been collected from Aarhus Municipality and Statistics Denmark. Both organizations have strict data policy requirements regarding person-identifiable information, which means that individual participant data cannot be made publicly available, even in anonymized form. Access to the data is restricted to approved researchers working on secure servers under the terms set by these institutions.