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Low back pain is a very common symptom. It occurs in high-income, middle-income, and low-income countries and all age groups from children to the elderly population. Globally, years lived with disability caused by low back pain increased by 54% between 1990 and 2015, mainly because of population increase and ageing, with the biggest increase seen in low-income and middle-income countries. Low back pain is now the leading cause of disability worldwide. For nearly all people with low back pain, it is not possible to identify a specific nociceptive cause. Only a small proportion of people have a well understood pathological cause—eg, a vertebral fracture, malignancy, or infection. People with physically demanding jobs, physical and mental comorbidities, smokers, and obese individuals are at greatest risk of reporting low back pain. Disabling low back pain is over-represented among people with low socioeconomic status. Most people with new episodes of low back pain recover quickly; however, recurrence is common and in a small proportion of people, low back pain becomes persistent and disabling. Initial high pain intensity, psychological distress, and accompanying pain at multiple body sites increases the risk of persistent disabling low back pain. Increasing evidence shows that central pain-modulating mechanisms and pain cognitions have important roles in the development of persistent disabling low back pain. Cost, health-care use, and disability from low back pain vary substantially between countries and are influenced by local culture and social systems, as well as by beliefs about cause and effect. Disability and costs attributed to low back pain are projected to increase in coming decades, in particular in low-income and middle-income countries, where health and other systems are often fragile and not equipped to cope with this growing burden. Intensified research efforts and global initiatives are clearly needed to address the burden of low back pain as a public health problem.

Many clinical practice guidelines recommend similar approaches for the assessment and management of low back pain. Recommendations include use of a biopsychosocial framework to guide management with initial non-pharmacological treatment, including education that supports self-management and resumption of normal activities and exercise, and psychological programmes for those with persistent symptoms. Guidelines recommend prudent use of medication, imaging, and surgery. The recommendations are based on trials almost exclusively from high-income countries, focused mainly on treatments rather than on prevention, with limited data for cost-effectiveness. However, globally, gaps between evidence and practice exist, with limited use of recommended first-line treatments and inappropriately high use of imaging, rest, opioids, spinal injections, and surgery. Doing more of the same will not reduce back-related disability or its long-term consequences. The advances with the greatest potential are arguably those that align practice with the evidence, reduce the focus on spinal abnormalities, and ensure promotion of activity and function, including work participation. We have identified effective, promising, or emerging solutions that could offer new directions, but that need greater attention and further research to determine if they are appropriate for large-scale implementation. These potential solutions include focused strategies to implement best practice, the redesign of clinical pathways, integrated health and occupational interventions to reduce work disability, changes in compensation and disability claims policies, and public health and prevention strategies.

Purpose Inconsistent reporting of outcomes in clinical trials of patients with non-specific low back pain (NSLBP) hinders comparison of findings and the reliability of systematic reviews. A core outcome set (COS) can address this issue as it defines a minimum set of outcomes that should be reported in all clinical trials. In 1998, Deyo et al. recommended a standardized set of outcomes for LBP clinical research. The aim of this study was to update these recommendations by determining which outcome domains should be included in a COS for clinical trials in NSLBP. Methods An International Steering Committee established the methodology to develop this COS. The OMERACT Filter 2.0 framework was used to draw a list of potential core domains that were presented in a Delphi study. Researchers, care providers and patients were invited to participate in three Delphi rounds and were asked to judge which domains were core. A priori criteria for consensus were established before each round and were analysed together with arguments provided by panellists on importance, overlap, aggregation and/or addition of potential core domains. The Steering Committee discussed the final results and made final decisions. Results A set of 280 experts was invited to participate in the Delphi; response rates in the three rounds were 52, 50 and 45 %. Of 41 potential core domains presented in the first round, 13 had sufficient support to be presented for rating in the third round. Overall consensus was reached for the inclusion of three domains in this COS: ‘physical functioning’, ‘pain intensity’ and ‘health-related quality of life’. Consensus on ‘physical functioning’ and ‘pain intensity’ was consistent across all stakeholders, ‘health-related quality of life’ was not supported by the patients, and all the other domains were not supported by two or more groups of stakeholders. Weighting all possible argumentations, the Steering Committee decided to include in the COS the three domains that reached overall consensus and the domain ‘number of deaths’. Conclusions The following outcome domains were included in this updated COS: ‘physical functioning’, ‘pain intensity’, ‘health-related quality of life’ and ‘number of deaths’. The next step for the development of this COS will be to determine which measurement instruments best measure these domains.

Background Low back pain (LBP) is one of the most disabling and costly disorders affecting modern society, and approximately 90% of patients are labelled as having non-specific LBP (NSLBP). Several interventions for patients with NSLBP have been assessed in clinical trials, but heterogeneous reporting of outcomes in these trials has hindered comparison of results and performance of meta-analyses. Moreover, there is a risk of selective outcome reporting bias. To address these issues, the development of a core outcome set (COS) that should be measured in all clinical trials for a specific health condition has been recommended. A standardized set of outcomes for LBP was proposed in 1998, however, with evolution in COS development methodology, new instruments, interventions, and understanding of measurement properties, it is appropriate to update that proposal. This protocol describes the methods used in the initial step in developing a COS for NSLBP, namely, establishing a core domain set that should be measured in all clinical trials. Methods/Design An International Steering Committee including researchers, clinicians, and patient representatives from four continents was formed to guide the development of this COS. The approach of initiatives like Core Outcome Measures in Effectiveness Trials (COMET) and Outcome Measures in Rheumatology (OMERACT) was followed. Participants were invited to participate in a Delphi study aimed at generating a consensus-based core domain set for NSLBP. A list of potential core domains was drafted and presented to the Delphi participants who were asked to judge which domains were core. Participant suggestions about overlap, aggregation, or addition of potential core domains were addressed during the study. The patients’ responses were isolated to assess whether there was substantial disagreement with the rest of the Delphi panel. A priori thresholds for consensus were established before each Delphi round. All participants’ responses were analysed from a quantitative and qualitative perspective to ascertain that no substantial discrepancies between the two approaches emerged. Discussion We present the initial step in developing a COS for NSLBP. The next step will be to determine which measurement instruments adequately cover the domains.

Low back pain is the leading worldwide cause of years lost to disability and its burden is growing alongside the increasing and ageing population.1 Because these population shifts are more rapid in low-income and middle-income countries, where adequate resources to address the problem might not exist, the effects will probably be more extreme in these regions. Most low back pain is unrelated to specific identifiable spinal abnormalities, and our Viewpoint, the third paper in this Lancet Series,2,3 is a call for action on this global problem of low back pain.

We propose a novel abstraction of the image segmentation task in the form of a combinatorial optimization problem that we call the multi-separator problem . Feasible solutions indicate for every pixel whether it belongs to a segment or a segment separator, and indicate for pairs of pixels whether or not the pixels belong to the same segment. This is in contrast to the closely related lifted multicut problem, where every pixel is associated with a segment and no pixel explicitly represents a separating structure. While the multi-separator problem is np -hard, we identify two special cases for which it can be solved efficiently. Moreover, we define two local search algorithms for the general case and demonstrate their effectiveness in segmenting simulated volume images of foam cells and filaments.

Correspondence to: C M P Jones caitlin.jones@sydney.edu.au What you need to know Analgesics have limited effect on low back pain and some, such as opioids and benzodiazepines, have substantial risks Oral and, less certainly, topical non-steroidal anti-inflammatory drugs have small benefits that may not be outweighed by risks (particularly gastrointestinal) for short term use for low back pain Acute low back pain typically improves within a few weeks without treatment; for chronic low back pain, the focus of management should be on non-pharmacological treatments to improve function and address the broader determinates of pain Low back pain is the world’s leading cause of disability.1 At any time, half a billion (9%) adults are affected.1 Many are prescribed, or use, analgesics for pain relief.2 In this article, we review what is known about common analgesics for treating non-specific low back pain (defined as pain without an identifiable structural or disease cause). Most people recover from acute low back pain within a few weeks irrespective of any treatment.5 Some people, however, develop chronic low back pain (typically defined as symptoms lasting for over three months), either as a fluctuating/recurring or continuous problem.10 Of those who present to primary care with acute low back pain, a quarter will have some ongoing pain or functional impairment at three months (chronic pain), although the estimates from individual studies range widely from 2% to 48%.11 Who is affected? Low back pain affects all people of all ages, genders, and ethnic or racial groups, although the point prevalence is slightly higher in women than men (~10% absolute difference consistently across age groups).12 Prevalence peaks in the 40-69 years age group.12 Disability resulting from low back pain is similar in high, middle, and lower income countries113 and in urban and rural areas.12 A 2018 umbrella review identified 54 risk factors associated with low back pain.14 Examples of potentially modifiable ones include current smoking (odds ratio (OR) 1.8 (95% confidence interval 1.3 to 2.7)), sleep problems (OR 3.2 (1.9 to 5.5)), >2 hours daily spent driving (OR 4.9 (1.4 to 16.4)), prolonged standing or walking (OR 2.9 (1.5 to 5.5)), and mental distress (OR 2.2 (1.3 to 3.7)).14 How is low back pain managed? Most international guidelines advise non-drug treatment and limited, careful use of some analgesic treatments, including those endorsed by the World Health Organisation, National Institute for Health and Care Excellence (NICE), and the American College of Physicians.15161718 People with non-specific low back pain should be advised to keep active (continue usual physical activities as much as possible), avoid bed rest (as it does not aid recovery),19 and use self management strategies such as heat packs.15 About one in five people with chronic low back pain will experience major life or work limitations and may benefit from further treatment.2021 For people with chronic non-specific low back pain, optimal approaches use physical and psychological therapies that improve function and address psychosocial contributors to low back pain (see infographic and table 1).15 Table 1 Summary of current guideline recommendations for non-specific low back pain Treatment Recommendation (certainty of evidence) Acute Certain analgesics (non-steroidal ani-inflammatory drugs (NSAIDs) and muscle relaxants) Effective (moderate) Superficial heat Effective (moderate) Acupuncture and needling therapies Effective (low) Massage Effective (low) Spinal manipulation therapy Effective (low) Exercise Not effective (low) Orthotics Not effective (low) Other analgesics Not effective (low) Chronic Multicomponent biopsychosocial care Effective (moderate) Structured exercise programmes Effective (moderate) Certain analgesics (NSAIDs and topical cayenne pepper) Effective (moderate to low) Acupuncture and needling therapies Effective (low) Structured exercise advice Effective (low) Cognitive behavioural therapy Effective (very low) Massage Effective (very low) Operant therapy Effective (very low) Spinal manipulation therapy Effective (very low) Mobility assistive products No evidence, good practice recommendation only Other analgesics Not effective (moderate to low) Therapeutic ultrasound Not effective (low) Orthotics (braces, supports) Not effective (very low) Pharmacological weight loss Not effective (very low) Traction Not effective (very low) Transcutaneous electrical stimulation Not effective (very low) Certainty of evidence as measured by GRADE approach (box 1) Acute treatment as recommended by 2017 American College of Physicians guideline18 Chronic treatment as recommended by 2023 WHO guidelines16 NICE guidance22 broadly agrees with the above except it recommends against acupuncture and makes recommendations on invasive/surgical procedures (consider radiofrequency denervation or spinal decompression for chronic low back pain in limited circumstances).