Adolescence is characterized by risk-taking and experimentation of new environments and behaviors, and health habits developed during this period have an impact on long-term health and well-being.1,2 These behaviors, such as alcohol consumption or tobacco use, are not only related to individual factors, but also to social factors.3-5

However, adolescents have the potential for successful and healthy development because human development is not predefined.6 In this sense, it is important to collect information on the health status of the population and its determinants.7 Although health behavior monitoring tools for young people have been used over the years, they have mostly focused in urban populations.8 However, in rural environments, the social, demographic, and geographic characteristics are distinct, and adolescents behave differently from their peers in urban areas.9 In this context, there is a need to create a surveillance system to monitor health behaviors and their determinants among adolescents in rural settings. Also, health behaviors are mostly investigated through cross-sectional surveys; therefore, it is important to implement longitudinal studies to analyze current health behaviors, how they change in the same adolescents, and their determinants over time. As proposed, in order to carry out a good surveillance of the determinants of health, the social determinants of health must be taken into account.7 The conceptual framework of reference is the Conceptual Framework of the determinants of social inequalities in health of the Commission for the Reduction of Health Inequalities in Spain.

The objective of the prospective cohort study (the DESKcohort project) is to describe and monitor health, health behaviors, and their related factors among 12 and 19-year-old adolescents schooled at centers of Compulsory Secondary Education or post-compulsory secondary education in Central Catalonia (Spain), considering social determinants of health.

The Determinants of Health in Secondary School Students in Central Catalonia (DESKcohort) project is a prospective longitudinal study with successive waves that provide comparable cross-sectional information and allow longitudinal assessment of changes in health behaviors (see table I in online Appendix). Participants are interviewed biannually (Table 1), creating a cohort of adolescents. To link students from one wave to the next and do a follow-up, a unique identifier was created for each student.

The geographical scope of the survey is Central Catalonia, which comprises the counties of Anoia, Bages, Berguedà, Moianès, Osona, and Solsonès, including 165 of the 947 municipalities in Catalonia. In this territory, there are currently 96 educational centers of Compulsory Secondary Education and two centers of post-compulsory education (baccalaureate and formative cycles). The study population consists of students in 2nd and 4th of compulsory secondary education (CSE); 2nd of post-compulsory secondary education (PCSE); and 2nd of Intermediate Level Training Cycles (ILTC). The DESKcohort project is a collaborative project led by the Fundació Universitària del Bages (FUB) with the participation of the Subdirectorate General for Addictions, HIV, Sexually Transmitted Infections and Viral Hepatitis; the Departament d’Educació; the Centre d’Estudis Epidemiològics sobre el VIH/SIDA de Catalunya (CEEISCAT); the Universitat Oberta de Catalunya (UOC); the Autonomous University of Barcelona; the Universidad de Alicante (UA); and the Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP).

Sixty-five (71.4%) and 84 (85.7%) centers have participated in the first and second waves, respectively. Table 1 describes the participation rate in each county. In the first wave, 7319 adolescents out of 11943 have participated (61.3%), and in the second wave, 9265 out of 14342 (64.6%). Table 2 describes the characteristics of the participants in the two waves of the DESKcohort project, in terms of sex, course grade, self-reported socioeconomic level, region of residence, and type of educational center (public or private). In the second wave, the prevalence of risky behaviors was higher than in the previous one; in both waves we generally observe that girls have engaged more in less healthy behaviors than boys. Of the 2505 people followed between the 1st and the follow-up period, 56.0% are girls. Also, within the cohort, 56.1% of people have been followed from 2nd to 4th year of CSE, 43.6% from 4th year of CSE to 2nd year of PCSE or 2nd year of ILTC. Therefore, we have included a table (see table III in online Appendix) detailing the sociodemographic characteristics of the people who in the first wave were likely to be followed up in the second wave, and the people who are followed up in the 2nd wave.

During the first three years of the DESKcohort project, data from 7319 and 9265 students in Central Catalonia have been analyzed for the 2019/20 and 2021/22 school years, respectively. Specifically, we performed a descriptive cross-sectional analysis and an analytic longitudinal analysis of the health behaviors of students in 2nd and 4th year of CSE, 2nd year of PCSE, and 2nd year of ILTC.

One limitation of this project is the exclusion of adolescents outside the formal educational system; therefore, the representativeness of the sample is limited to students enrolled in educational centers of the territory. However, education in our country is compulsory until the age of 16; therefore, this limitation would be relevant only for adolescents in the 2nd year of post-compulsory secondary education, a fact that is minimized by including adolescents in the 2nd year of ILTC. Another limitation is that not all educational centers invited to participate did participate in the end. Moreover, nor all students in the participating educational centers responded to the questionnaire. However, in five of the six counties, in the 2nd wave over 90% of the educational centers decided to participate in the study (Table 1). The fact that participation may vary in each wave makes it difficult to establish a stable cohort that monitors individuals from 2nd year of CSE to 2nd year of PCSE or 2nd year of ILTC. This can lead to a low follow-up rate throughout the entire academic trajectory, and individuals are followed intermittently without sustained progress. Finally, responses to the questionnaire are self-reported and data could suffer some information bias (for example, because of social desirability and recall bias). However, the questionnaire included questions with a high validity for adolescents: for example, CAST and AUDIT-C13,25 in the case of substance use; and other tests in the case of bullying, mental health, and problematic screen use26-29.

As a strength of the DESKcohort project, we highlight the importance for the region to have monitoring data on the health behaviors of adolescents, and to be able to analyze the effect of contextual factors and social determinants on them, besides the high participation rate and sample size. Also, after each wave, we returned the results to participating educational centers and regional institutions. This allows the educational centers to detect and identify health needs to implement programs adapted to these needs among their students. In addition, a general results report is published biannually, which allows the identification of the health needs of the population. Finally, as a longitudinal monitoring tool, the DESKcohort project complements other information systems to understand health and its determinants among adolescents in Catalonia. It represents a crucial source of information for both local (educational centers, county councils, municipalities, and health and third sector entities) and national policy making institutions (Health Department, Education Department). This allows them to improve health promotion strategies and public health programs to address the identified needs and evaluate future interventions.

Data collected and generated in the DESKcohort project are available free of charge for scientific research. Following the data cleaning, processing and the generation variables of each wave, people can ask for obtain some modules of variables. To obtain data, researchers could be addressed DESKcohort website (http://deskcohort.cat/en/databases/). Then, DESKcohort checks the purpose of the request and the affiliation of the applicant and provides the database, always without the identification code data created. As of January 2023, data from the first waves 1 and 2 are available (transversal and longitudinal data).

Mariano Hernán-García.

A. Espelt is the principal investigator of the DESKcohort project, and he conceived and led the preparation of the research protocol. M. Bosque-Prous, E. Teixidó-Compañó, C. Folch, J. Colom, J. Casabona, C. Vives-Cases and E. Fernandez reviewed and proposed questions from their respective areas of expertise to be included in the DESKcohort questionnaire. J. Rogés, M. Bosque-Prous, H. González-Casals, G. Drou, E. Teixidó-Compañó and A. Espelt collected the data. J. Rogés, H. González-Casals, G. Drou and A. Espelt performed the data analysis, interpretation of the results and creation of the tables. J. Rogés drafted the article. A. Espelt and M. Bosque-Prous reviewed the structure and design of the manuscript. All the coauthors discussed, reviewed and approved the manuscript in its last version, and made important contributions from their field of expertise that contributed to enriching the manuscript.