Trajectories of pain in adolescents: a prospective cohort study.

Identification of different patterns of change in pain over time - trajectories - has the potential to provide new information on the course of pain. Describing trajectories among adolescents would improve understanding of how pain conditions can develop. This prospective cohort study identified distinct trajectories of pain among adolescents (11-14 years) in the general population (n=1336). Latent class growth analysis was carried out on the self-reported frequency of back pain, headache, stomach pain and facial pain, which was collected every 3 months for 3 years. Forty four percent of adolescents had a 'painful' trajectory for at least one pain site, and 12% reported persistent pain at one or more pain site. Headache was the most common; 25% of subjects were in a 'painful' trajectory and 5% reported persistent pain. Back pain and stomach pain were also common, with 22% and 21% of subjects in painful trajectories, respectively. Facial pain was the least common, with only 10% in a painful trajectory, and 1% reporting persistent pain. Trajectory characteristics were similar at baseline across pain sites, with the more painful trajectories having significantly higher levels of depression and somatization, lower life satisfaction and more females. Trajectories did not differ significantly at baseline in physical activity levels or BMI. Agreement of trajectory membership among pain sites was moderate. In summary, reporting a painful trajectory was common among adolescents, but persistent pain was reported by a small minority, and was usually experienced at a single pain site.