Background & Aims Chronic illnesses – such as chronic pain – are risk factors that may interfere with the physical, emotional, social, and educational development of children and adolescents. Research conducted in countries other than Portugal, suggests that chronic pain is a common problem in this population that is frequently associated with poorer physical, psychological function, and cognitive function, as well as poor sleep quality, and family functioning when compared to their healthy counterparts. In addition, chronic pain-related school absenteeism is common, affecting children’s/adolescent’s school performance and their ability to maintain healthy peer relationships. Children and adolescents with chronic pain are more socially isolated and less well accepted by their peers. Despite the global recognition of these challenges, little is known about the prevalence, determinants, and impact of chronic pain in Portuguese children and adolescents. This study will seek to address this knowledge gap. Methods Data will be collected from 1800 children and adolescents (age range: 8 – 16) attending school in continental Portugal. Collaboration from schools has been obtained following the acceptance of participation by school boards. Parents of children and adolescents attending partner schools will be mailed a letter explaining the study aims and procedures. Consent and agreements to participate will be obtained from both parents and students. The participants, stratified by sex, age, and area of residence, will complete an in-person survey assessing sociodemographic and pain-related clinical history information, physical, psychological, and social function, and school performance. Participants meeting criteria for having chronic pain (having pain for ? 50% of the days in the prior 3 months) , will also be asked to provide information about pain intensity and pain locations. Results Statistical analyses planned include: (1) descriptive statistics (e.g., frequencies, means, and standard deviations) for sociodemographic variables and pain-related measures to characterize the study sample and to estimate the prevalence of chronic pain in the study population; (2) between-group (individuals with chronic pain vs. individuals without chronic pain) comparisons of sociodemographic variables; (3) examination of the associations between the presence and severity of chronic pain and the measures of physical and psychological function, sleep quality , and school performance. Conclusions This study will provide important new information regarding the prevalence and impact of chronic pain in children and adolescents in Portugal. The study results will be useful to stakeholders and to policy makers for enhancing the quality of life of young people with chronic pain. Knowledge about the impact of and factors associated with chronic pain will improve clinicians and researchers’ ability to develop more effective early interventions targeting this population.

This study is supported by a La Caixa Foundation research grant.

• Psychology - Social Sciences