Background. Low back-related leg pain (LBLP) is clinically diagnosed as referred leg pain or sciatica. Within the spectrum of LBLP there may be unrecognised subgroups of patients. This study aimed to identify and describe clusters of LBLP patients using latent class analysis (LCA). Methods. The study population were 609 LBLP primary care consulters. Variables from clinical assessment were included in the LCA. Characteristics of the statistically identified clusters were described and compared to the clinically defined groups of LBLP patients. Results. A five cluster solution was optimal. Cluster one (n=104) had mild leg pain severity, no clinical signs suggestive of sciatica and more anxiety. Cluster two (n=122), three (n=188) and four (n=69) represented mild, moderate and severe sciatica in terms of response to clinical assessment items, pain severity and impact on function. Cluster five (n=126) was more difficult to define based on response to clinical assessment items (below knee pain and possible neural tension) and had a similar severe profile to cluster four in terms of high pain, disability, psychosocial factors, work impact and risk of poor outcome; but had longer duration pain and more comorbidities. Cluster three consistently mirrored the profile of the overall group of patients with a clinical diagnosis of sciatica. Cluster one mirrored the referred leg pain group. Conclusion. This is the first study that used LCA to classify LBLP patients, including sciatica. These clusters could represent more homogenous groups that may require different treatment approaches. Further work will describe the clinical course and longer term outcomes of these clusters. No conflicts of interest. S Stynes is supported by an NIHR/CNO Clinical Doctoral Research Fellowship (CDRF-2010-055). Dr Konstantinou is supported by a HEFCE/NIHR Senior Clinical Lectureship. Professor Hay is a NIHR Senior Investigator

Follow-up radiographs are usually used as the reference standard for the diagnosis of suspected scaphoid fractures. However, these are prone to errors in interpretation. We performed a meta-analysis of 30 clinical studies on the diagnosis of suspected scaphoid fractures, in which agreement data between any of follow-up radiographs, bone scintigraphy, magnetic resonance (MR) imaging, or CT could be obtained, and combined this with latent class analysis to infer the accuracy of these tests on the diagnosis of suspected scaphoid fractures in the absence of an established standard. The estimated sensitivity and specificity were respectively 91.1% and 99.8% for follow-up radiographs, 97.8% and 93.5% for bone scintigraphy, 97.7% and 99.8% for MRI, and 85.2% and 99.5% for CT. The results were generally robust in multiple sensitivity analyses. There was large between-study heterogeneity for the sensitivity of follow-up radiographs and CT, and imprecision about their sensitivity estimates. If we acknowledge the lack of a reference standard for diagnosing suspected scaphoid fractures, MRI is the most accurate test; follow-up radiographs and CT may be less sensitive, and bone scintigraphy less specific

Background and purpose. Over the past decade, it has become apparent that more often than not musculoskeletal pain occurs in more than one site in an individual, and traditional approaches, where pain has been studied as a narrow site-specific problem, are often not feasible. The overall aim of this study is to describe clusters of pain using a large population-based sample. This presentation will focus specifically on musculoskeletal co-complaints in back pain sufferers. Methods and results. The Danish National Institute of Public Health has since 1987 conducted national representative health interview surveys of the adult Danish population some of which have included questions on musculoskeletal complaints. We used latent class analysis to identify latent classes of musculoskeletal complaints that occurred alongside a primary complaint of back pain. In addition, probabilities that specific sites occurred as co-complaints were determined. Three latent classes were identified and they exhibited quite different patterns of musculoskeletal co-complaints. The most commonly occurring class had a low probability of any co-complaints, the second most commonly occurring class had a high probability of pain in the neck, shoulders and mid-back, while the least commonly occurring class had very high probabilities of pain at all other body sites. Conclusions. Latent class analysis can be used to identify distinctly different groups of pain patterns in persons primarily complaining of back pain. The three groups identified likely have very different prognoses. Conflicts of Interest. None. Source of Funding. None. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

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

Introduction. Pain related to knee osteoarthritis (OA) is a complex phenomenon that cannot be fully explained by radiographic disease severity. We hypothesized that pain phenotypes are likely to be derived from a confluence of factors across multiple domains: knee OA pathology, psychology, and neurophysiological pain processing. The purpose of this study was to identify distinct phenotypes of knee OA, using measures from the proposed domains. Methods. Data from 3494 subjects participating in the Osteoarthritis Initiative (OAI) study was analyzed. Variables analyzed included: radiographic OA severity (Kellgren-Lawrence grade), isometric quadriceps strength, Body Mass Index (BMI), comorbidities, CES-D Depression subscale score, Coping Strategies Questionnaire Catastrophizing subscale score, number of pain sites, and knee tenderness on physical examination. Variables used for comparison across classes included pain severity, WOMAC disability score, sex and age. Latent Class Analysis was performed. Model solutions were evaluated using the Bayesian Information Criterion. One-way ANOVAs and post hoc least significance difference tests were used for comparison of classes. Results. A four-class model was identified. Class 1 (57% of study population) had lesser radiographic OA, little psychological involvement, greater strength, and less pain sensitivity. Class 2 (28%) had higher rates of knee joint tenderness. Class 3 (10%) had greater psychological distress and more bodily pain sites. Class 4 (4%) had more comorbidities. Additionally, Class 1 was the youngest, had the lowest disability, and least pain. Class 4 was the oldest. Class 2 had a higher proportion of females. Class 3 had the worst disability and most pain. Conclusions. Four distinct pain phenotypes for knee OA were identified. Psychological factors, knee tenderness, and comorbidities appear to be important in defining phenotypes of OA-related pain. Therapies in knee OA should take a multicomponent approach, recognizing the factors most relevant to an individual's experience of pain

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

A prospective study was performed to develop a clinical prediction rule that incorporated demographic and clinical factors predictive of a fracture of the scaphoid. Of 260 consecutive patients with a clinically suspected or radiologically confirmed scaphoid fracture, 223 returned for evaluation two weeks after injury and formed the basis of our analysis. Patients were evaluated within 72 hours of injury and at approximately two and six weeks after injury using clinical assessment and standard radiographs. Demographic data and the results of seven specific tests in the clinical examination were recorded.

There were 116 (52%) men and their mean age was 33 years (13 to 95; sd 17.9). In 62 patients (28%) a scaphoid fracture was confirmed. A logistic regression model identified male gender (p = 0.002), sports injury (p = 0.004), anatomical snuff box pain on ulnar deviation of the wrist within 72 hours of injury (p < 0.001), and scaphoid tubercle tenderness at two weeks (p < 0.001) as independent predictors of fracture. All patients with no pain at the anatomical snuff box on ulnar deviation of the wrist within 72 hours of injury did not have a fracture (n = 72, 32%). With four independently significant factors positive, the risk of fracture was 91%.

Our study has demonstrated that clinical prediction rules have a considerable influence on the probability of a suspected scaphoid fracture. This will help improve the use of supplementary investigations where the diagnosis remains in doubt.

A suspected fracture of the scaphoid remains difficult to manage despite advances in knowledge and imaging methods. Immobilisation and restriction of activities in a young and active patient must be balanced against the risks of nonunion associated with an undiagnosed and undertreated fracture of the scaphoid.

The assessment of diagnostic tests for a suspected fracture of the scaphoid must take into account two important factors. First, the prevalence of true fractures among suspected fractures is low, which greatly reduces the probability that a positive test will correspond with a true fracture, as false positives are nearly as common as true positives. This situation is accounted for by Bayesian statistics. Secondly, there is no agreed reference standard for a true fracture, which necessitates the need for an alternative method of calculating diagnostic performance characteristics, based upon a statistical method which identifies clinical factors tending to associate (latent classes) in patients with a high probability of fracture.

The most successful diagnostic test to date is MRI, but in low-prevalence situations the positive predictive value of MRI is only 88%, and new data have documented the potential for false positive scans. The best strategy for improving the diagnosis of true fractures among suspected fractures of the scaphoid may well be to develop a clinical prediction rule incorporating a set of demographic and clinical factors which together increase the pre-test probability of a fracture of the scaphoid, in addition to developing increasingly sophisticated radiological tests.

The December 2012 Wrist & Hand Roundup³⁶⁰ looks at: the imaging of scaphoid fractures; splinting to help Dupuytren’s disease; quality of life after nerve transfers; early failure of Moje thumbs; electra CMCJ arthroplasty; proximal interphalangeal joint replacement; pronator quadratus repair in distal radius fractures; and osteoporosis and wrist fractures.