Background and purpose. Trajectories of change over time can illustrate the course of pain. Back pain trajectories have previously been identified among adults. Understanding different patterns of back pain among adolescents could shed light on how persistent back pain develops. We aimed to identify and compare trajectories of back pain among adolescents in the general population. Methods and results. This prospective cohort study followed 1,336 adolescents (initially aged 11 years) every three months for three years, using self-completion questionnaires. Latent class growth analysis was used to cluster subjects into distinct trajectories of back pain. Six clusters were identified. Most subjects (78%) had very low likelihood of back pain throughout follow-up. The second largest cluster (10%) had relatively low and falling probability of back pain. Two clusters (4% each) showed increasing probability of back pain. One cluster had a peak likelihood of pain around age 13 (2%). The smallest cluster (1%) had very high probability of back pain throughout follow-up. The more painful trajectories had significantly fewer males, higher levels of depression and somatization, and lower life satisfaction at baseline, but differed little in physical activity or BMI. Conclusions. Over a fifth of adolescents had trajectories indicating back pain, but a minority had persistent pain problems. Poorer baseline psychological status and female gender were linked with more frequently experienced pain. Trajectories indicating rising or persistent pain might be illustrating the beginning of a long-term pain problem. Headache, facial pain and stomach pain trajectories were also identified in this sample; findings were similar to back pain

Purposes of the study and background. Pain of lumbar facet-joint origin is a common cause of low back pain in adults, and may lead to chronic pain and disability. At present, there is no definitive research to support the use of targeted lumbar facet-joint injections to manage this pain. The study's objective was to assess the feasibility of carrying out a definitive study to evaluate the clinical- and cost-effectiveness of lumbar facet-joint injections compared to a sham procedure. Summary of methods and results. This was a blinded parallel two-arm pilot randomised controlled trial. Adult patients referred to the pain and orthopaedic clinics at Barts Health NHS Trust with non-specific low back pain of at least three months' duration were considered for inclusion. Participants who had a positive result following diagnostic single medial branch nerve blocks were randomised to receive either intra-articular lumbar facet-joint injections with steroid or a sham procedure. All participants were invited to attend a combined physical and psychological programme. Questionnaires were used to assess a range of pain and disability-related issues. Healthcare utilisation and cost data were also assessed. Of 628 participants screened for eligibility, 9 were randomised to receive the study intervention and 8 participants completed the study. Conclusions. Due to the small numbers of participants recruited to the study, we were unable to draw any conclusions on the effectiveness of intra-articular lumbar facet-joint injections in the management of non-specific low back pain. We however demonstrated our ability to develop a robust study protocol and deliver the intended interventions safely, thus addressing many of the feasibility objectives. Stronger collaborations with primary care may improve the recruitment of patients earlier in their pain trajectory, suitable for inclusion in a future trial. Conflicts of interest: None. Sources of funding: National Institute for Health Research Health Technology Assessment programme grant (reference number 11/31/02)

Background and objectives. Low back pain (LBP) is a major health challenge globally. Research has identified common trajectories of pain over time. We aimed to investigate whether trajectories described in one primary care cohort can be confirmed in another, and to determine the prognostic value of factors collected 5 years prior to the identification of the trajectory. Methods and results. The study was carried out on 281 patients who had consulted primary care for LBP, at that point completed a baseline questionnaire, and then returned a questionnaire at 5-years follow-up plus at least 3 (of 6) subsequent monthly questionnaires. Baseline factors were measured using validated tools. Pain intensity scores from the 5-year follow-up and monthly questionnaires were used to cluster participants into 4 previously derived pain trajectories (no or occasional mild, persistent mild, fluctuating, persistent severe), using latent class analysis. Posterior probabilities of belonging to each cluster were estimated for each participant. The posterior probabilities for the assigned clusters were very high (>0.90) for each cluster except for the smallest ‘fluctuating’ cluster (0.74). Lower social class (OR 2.9; 95% CI 1.2, 7.0), higher pain intensity (1.6 per unit; 1.2, 2.2), and pain duration greater than 3 years (2.7; 1.0, 7.3), were significantly associated with a more severe trajectory 5-years later, as were higher physical disability, emotional impact of pain, and perception pain will last a long time. Conclusion. LBP trajectories identified previously appear generalizable. These allow better understanding of the long-term course of LBP and effective management tailored to individual trajectories needs to be identified. Conflicts of interest. None. Funding. This work was supported by the following grants: Arthritis Research UK [13413], the Wellcome Trust [083572] and the Medical Research Council Prognosis Research Strategy (PROGRESS) Partnership [G0902393/99558]. Time from NEF was supported by an NIHR Research Professorship (NIHR-RP-011-015). NEF is an NIHR Senior Investigator. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health