Introduction. A minority of patients with chronic low back pain (CLBP) account for a majority of disability and costs. This subgroup has potentially most to gain from effective treatment. The Groningen Spine Cohort will provide a 10-year prospective insight into the burden of CLBP for patients referred to multispecialty tertiary spine care in the Netherlands. This study reports first baseline results. Objective. To study the personal and societal impact of CLBP in patients visiting the UMCG tertiary spine center. Patients. Adult patients with CLBP. Methods. Patient-reported baseline questionnaire and health insurance costs one year prior to visiting the Spine Center. Primary outcomes: NIH minimal dataset Impact Stratification score (range 8–50), functioning (Pain Disability Index, PDI; 0–70), quality of life (EuroQol-5D, EQ5D; -0.33–1.00), work ability (single-item Work Ability Score, WAS; 0–10), work participation (absenteeism, disability), and health insurance costs. Descriptive statistics were applied. Results. N=1503 patients (age m=46.3, sd=12.8 years, 57% female) were included. NIH Impact Stratification m=35.2±7.5; severe impact (≥35) for 58% of patients. PDI = 38.2±14.1; EQ5D = 0.44±0.30; WAS = 3.8±2.9. Absenteeism: 43% of workers. Permanent work disability: 17%. Health insurance costs: med= €2432, IQR €4739. Discussion And Conclusions. In patients seeking multispecialty tertiary spine care, the personal and societal impact of CLBP is very high. Costs are substantially higher than what is already known about the burden of the average patient with CLBP. Clinical Message. More effective personalized stepped and matched care is urgently needed to reduce the burden of CLBP in a subgroup of patients seeking multispecialty tertiary spine care. No conflicts of interest. Sources of Funding: Funding from the University Medical Center Groningen

Background. Leg pain frequently accompanies low back pain and is associated with increased levels of disability and higher health costs than simple low back pain. Distinguishing between different types of low back- related leg pain (LBLP) is important for clinical management and research applications. The aim of this systematic review was to identify, describe and appraise papers that classify or subgroup populations with LBLP. Methods. The search strategy involved nine electronic databases including Medline and Embase, reference lists of eligible studies and relevant reviews. Selected papers were quality appraised independently by two reviewers using a standardised scoring tool. Results. Of 13,337 potential eligible citations, 49 relevant papers were identified that reported on 20 classification systems. Papers were grouped according to purpose and criteria of the classification systems. Five themes emerged: (i) pathoanatomical sources of pain (ii) clinical features, (iii) pain mechanisms, (iv) treatment based approach and (v) screening tools and prediction rules. Four of the twenty systems focused specifically on LBLP populations. Pain mechanisms and treatment based approach systems scored highest following quality appraisal as authors generally included statistical methods to develop their classifications and supporting work had been published on the systems' validity, reliability and generalizability. Conclusion. Numerous classification systems exist that include patients with leg pain, a minority of them focus specifically on distinguishing between different presentations of leg pain. Further work is needed to identify clinically meaningful subgroups of LBLP patients, ideally based on large primary care cohort populations and using stringent methods for classification system development. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting. Conflicts of interest: No conflicts of interest. S Stynes is supported by an NIHR/HEE Clinical Doctoral Research Fellowship. Dr Konstantinou is supported by an HEFCE/NIHR Senior Clinical Lectureship. Professor Dunn is supported by the Wellcome Trust (083572)