Chronic backpain among adolescents in Denmark: trends 1991-2018 and association with socioeconomic status.

Chronic backpain among adolescents is important because the prevalence is high, above 10%, and more than 10% of all adolescents experience impacts on important day-to-day activities. Chronic backpain tracks into adulthood and is associated with several health problems. The objective was to study trends in the prevalence of chronic backpain among adolescents 1991-2018, to examine the association with socioeconomic status (SES), and whether this association changed over time. The study used data from eight comparable cross-sectional school surveys of nationally representative samples of 11-15-year-olds in 1991, 1994, 1998, 2002, 2006, 2010, 2014, and 2018, which constitute the Danish arm of the international Health Behaviour in School-aged Children (HBSC) study. The participation rate was 74.6% of the eligible study population, n = 29,952. Chronic backpain was defined as self-reported backpain daily or several days a week during the last 6 months. The prevalence of chronic backpain was 11.1%, significantly increasing from 8.9% in 1991 to 11.7% in 2018. The OR for chronic backpain was 1.20 (95% CI: 1.10-1.31) in middle, and 1.56 (95% CI: 1.41-1.73) in low compared to high SES. Sensitivity analyses with two other cut-points for backpain frequency showed similar associations.Conclusion: Chronic backpain is common among adolescents and the prevalence increased from 1991 to 2018. The prevalence was highest in lower SES families. We recommend increased efforts to prevent chronic backpain. What is Known: • Chronic backpain among adolescents is common, has a high burden of disability, is associated with several health problems, and tracks into adulthood. What is New: • The prevalence of chronic backpain among adolescents in Denmark increased from 8.9% in 1991 to 11.7% in 2018. • The prevalence was highest among adolescents from lower SES families.