Does pain duration and other variables measured at baseline predict re-referral of low back pain patients managed on an evidence-based pathway? A cohort study.

OBJECTIVE: To explore the association between baseline pain duration and the likelihood of re-referral of patients with low back pain (LBP) managed on the evidence-based North East of England Regional Back Pain and Radicular Pain Pathway (NERBPP). STUDY DESIGN: Longitudinal, observational cohort study. METHODS: In all, 12,509 adults with LBP were identified as having been discharged from the pathway, between May 2015 and December 2019. To quantify any association between baseline pain duration and the likelihood of re-referral, two statistical modelling approaches, were used: logistic regression models for odds ratios and generalised linear models with a binomial link function in order to quantify risk differences. RESULTS: Twenty-five percent of patients with LBP, who were discharged, re-referred for management over a 4.5-year period. A large difference in pain duration of 2 SD days was statistically associated with re-referral, with an odds ratio of 1.22 (95% CI: 1.03, 1.44) and a risk difference of 3.6% (95% CI: 0.6, 6.6). Nevertheless, the predictive value of an individual's pain duration was found to be weak for re-referral. Higher baseline disability [odds ratio of 1.40 (95% CI: 1.07, 1.83)] and a younger age at baseline [odds ratio of 0.73 (95% CI 0.61, 0.86)] were also associated with an increased risk of re-referral. CONCLUSIONS: Baseline pain duration, disability and younger age are statistically associated with re-referral onto the NERBPP. However, the value of these variables for predicting an individual's risk of re-referral is weak. CONTRIBUTION OF PAPER.

Does Duration of Pain at Baseline Influence Longer-term Clinical Outcomes of Low Back Pain Patients Managed on an Evidence-Based Pathway?

STUDY DESIGN: Nonrandomized longitudinal observational study. OBJECTIVE: The aim of this study was to evaluate the association between baseline pain duration and medium-to-long term clinical outcomes, in low back pain (LBP) patients enrolled on the North East of England Regional Back Pain and Radicular Pain Pathway (NERBPP). SUMMARY OF BACKGROUND DATA: The NERBPP is based upon National Institute for Health and Care Excellence (NICE) guidelines. These guidelines no longer differentiate management of LBP patients based on pain duration. Medium-to-long term data from the NERBPP is lacking. METHODS: Between May 2015 and December 2019, 786 and 552 LBP patients from the NERBPP returned 6-month and 12-month follow-up outcome measures, respectively. Outcomes included pain (Numerical rating scale), function (Oswestry Disability Index) and quality-of-life (EuroQol five-dimension, five-level questionnaire), analyzed using a series of covariate-adjusted models. Patients were categorized into four groups based upon baseline pain duration: <3 months, ≥3 to <6 months, ≥6 months to <12 months, ≥12 months. RESULTS: Patients with <3 months duration demonstrated clinically important improvements on all outcomes, at both follow-ups. The improvements in outcomes from this group were larger than those in the ≥12 month's duration group (P < 0.05), these group differences in change, in some cases surpassed our threshold for clinical relevance. Functional improvements in those with ≥12 month's duration were not clinically relevant at either follow-up. All patients, regardless of baseline pain duration, reported similar levels of readiness to self-manage at the 12-month follow-up. CONCLUSION: Baseline pain duration would appear to be of clinical importance. Patients with shorter baseline pain duration demonstrated better outcomes. Those with ≥12 month's duration of pain may need additional support during their management to achieve clinically relevant functional improvements in the medium-to-long term. These findings raise questions about the decision by NICE to move away from duration of pain to differentiate management of LBP patients.Level of Evidence: 3.

Does Duration of Pain at Baseline Influence Clinical Outcomes of Low Back Pain Patients Managed on an Evidence-based Pathway?

STUDY DESIGN: Longitudinal observational study. OBJECTIVE: To investigate the association between the duration of pain at baseline and the clinical outcomes of patients with low back pain (LBP) enrolled on the North East of England Regional Back Pain and Radicular Pain Pathway (NERBPP). SUMMARY OF BACKGROUND DATA: The NERBPP is a clinical pathway based upon National Institute for Health and Care Excellence (NICE) guidelines (2009) for LBP of <1-year duration. Recent changes to NICE guidelines (2016) advocate the same management for all LBP patients regardless of pain duration. METHODS: Patients with LBP referred onto the NERBPP by their General Practitioner between May 2015 and January 2017 were included. Data from 667 patients, who provided pre- and post data for pain (Numerical rating scale), function (Oswestry Disability Index), quality-of-life (EuroQol five-dimension, five-level questionnaire), anxiety (the Generalized Anxiety Disorder Screener), and depression (the Patient Health Questionnaire), were analyzed using a series of covariate-adjusted models. Patients were categorized into four groups based upon baseline pain duration: <3 months, ≥3 to <6 months, ≥6 months to <12 months, ≥12 months. RESULTS: Each group showed improved outcomes greater than the minimal clinically important difference (MCID) for each measure as defined in NICE guidelines (2016). There was a trend toward better outcomes for those with shorter pain durations. The magnitude of the differences between the groups, in most instances, was below the MCID. For example, mean improvement in function for those with baseline pain duration <3 months was 20 points and 12 points for those of pain duration ≥12 months, both above the MCID of ≥10. CONCLUSION: Patients with different durations of LBP at baseline improved on the NERBPP, supporting the recent modification to NICE guidelines. However, those with shorter durations of pain may have superior outcomes in the short term, suggesting added benefit in getting patients onto the pathway in the early stages of LBP. LEVEL OF EVIDENCE: 3.

Do L5 and s1 nerve root compressions produce radicular pain in a dermatomal pattern?

STUDY DESIGN: Observational case series. OBJECTIVE: To compare the pattern of distribution of radicular pain with published dermatome charts. SUMMARY OF BACKGROUND DATA: Dermatomal charts vary and previous studies have demonstrated significant individual subject variation. METHODS: Patients with radiologically and surgically proven nerve root compression (NRC) caused by prolapsed intervertebral disc completed computerized diagrams of the distribution of pain and pins and needles. Ninety-eight patients had L5 compressions and 83 had S1 compressions. RESULTS: The distribution of pain and pins and needles did not correspond well with dermatomal patterns. Of those patients with L5 NRC, only 22 (22.4%) recorded any hits on the L5 dermatome on the front, and only 60 (61.2%) on the back with only 13 (13.3%) on both. Only 1 (1.0%) patient placed more than 50% of their hits within the L5 dermatome. Of those patients with S1 NRC, only 3 (3.6%) recorded any hits on the S1 dermatome on the front, and only 64 (77.1%) on the back with only 15 (18.1%) on both. No patients placed more than 50% of their hits within the S1 dermatome. Regarding pins and needles, 27 (29.7%) patients with L5 NRC recorded hits on the front alone, 27 (29.7%) on the back alone, and 14 (15.4%) on both. Nineteen (20.9%) recorded more than 50% of hits within the L5 dermatome. Three (3.6%) patients with S1 NRC recorded hits on the front alone, 44 (53.0%) on the back alone, and 18 (21.7%) on both. Twelve (14.5%) recorded more than 50% of hits within the S1 dermatome. CONCLUSION: Patient report is an unreliable method of identifying the anatomical source of pain or paresthesia caused by nerve root compression. LEVEL OF EVIDENCE: 4.

Reliability of clinical assessment in diagnosing cauda equina syndrome.

Cauda equina syndrome (CES) is a neurological syndrome presenting with non-specific symptoms and signs that often leads to diagnostic confusion and delay. Acute onset CES is a surgical emergency. The common aetiology is a prolapsed lumbar disc. If the diagnosis is missed, it can have devastating consequences for the patient and a high financial cost to healthcare providers. The objective of this study was to evaluate the efficacy of clinical assessment in clinching the diagnosis. Eighty patients who underwent urgent clinical assessment and magnetic resonance imaging (MRI) for suspected CES over a 1-year period (from January 1st 2008 to 31 December 2008) were included in the study. Fifteen of these patients had a CES and underwent urgent lumbar discectomy and decompression. Medical notes and MRI scans of all these patients were reviewed. The presenting symptoms and signs were analysed against a positive MRI scan. Chi-square test with Yates correction was used to test association of each clinical symptom and sign for a positive MRI. In this study, only 18.8% of assessed patients had a CES producing compression seen on the MRI. Presence of saddle sensory deficit was the only clinical feature with a statistically significant association with MRI positive CES (p = 0.03). This series shows that saddle sensory deficit has a higher predictive value than other clinical features in diagnosing a CES. However, as there is no symptom or sign which has an absolute predictive value in establishing the diagnosis of CES, any patient in whom a reasonable suspicion of CES arises must undergo urgent MRI to exclude this diagnosis.

EMG analysis of lumbar paraspinal muscles as a predictor of the risk of low-back pain.

Studies of EMG power spectra have established associations between low-back pain (LBP) and median frequency (MF). This 2-year prospective study investigates the association of LBP with EMG variables over time. 120 health care workers underwent paraspinal EMG measurements and assessment of back pain disability. The EMG recordings were performed under isometric trunk extension at 2/3 maximum voluntary contraction and acquired from erector spinae muscles at the level of L4/L5. 108 (90%) subjects were reviewed at a minimum 2-year follow up. 16 out of 93 subjects with no history of chronic low-back pain became worse as measured by time off work, disability, reported pain and self-assessment rating. The value of the EMG variable half-width at inception demonstrated significant association with changes in subject's outcome measure and their own assessment of their LBP at follow up (p < 0.05). Based on self-assessment data, subjects with no history of chronic LBP with half-width of greater than 56 Hz were at threefold greater risk of developing back pain compared with the remainder of the population (p = 0.045). The value of the initial median frequency (IMF) and MF slope at inception were also associated with the subjects' own assessment of LBP at follow up. Subjects with an IMF greater than 49 Hz were at 5.8-fold greater risk of developing back pain compared with the remainder of the population (p = 0.014). EMG variables recorded from lumbar paraspinal muscles can identify a sub group of subjects at increased risk of developing low-back pain in the future.

Short-term prospective memory deficits in chronic back pain patients.

OBJECTIVE: Chronic pain, particularly low back pain, is widespread. Although a great deal is known about the impact that this has on quality of life and physical activity, relatively little has been established regarding the more cognitive effects of pain. This study aims to find out whether individuals with chronic pain experience memory deficits in prospective memory (PM), the process of remembering to do things at some future point in time. Examples of PM include remembering to keep an appointment, such as a visit to a clinic, or to perform a particular task, such as paying a bill on time. METHODS: The PM of 50 participants with chronic pain was compared with 50 pain-free participants. Each participant completed the Prospective Memory Questionnaire, which assesses three aspects of prospective memory (short-term habitual, long-term episodic, and internally cued), and records the use of strategies to aid remembering. RESULTS: In comparison to those not in pain, participants with chronic pain had significantly impaired short-term prospective memory, an effect which was evident even after co-varying use of analgesics and other drugs. CONCLUSIONS: These findings provide new insights into prospective memory dysfunction in people with chronic pain. Possible mechanisms for this dysfunction are discussed and suggestions for future research given.

Outcome assessment: recommendations for daily practice.

The choice of instruments for the assessment of outcome in spinal surgery is bewildering. For day-to-day practice, however, consideration of the purpose for which information is required allows construction of simple strategies for data collection. Recommendations are made for short and convenient data sets for use in personal audit, clinical governance, benchmarking, patient selection and business planning. No simple data set can measure in detail every aspect of practice, but use of these recommendations will provide information that will be of great value to the spinal surgeon and ultimately to his patients.

Back related outcome assessment instruments.

A literature review of the most widely used condition specific, self administered assessment questionnaires for low back pain had been undertaken. General and historic aspects, reliability, responsiveness and minimum clinically important difference, external validity, floor and ceiling effects, and available languages were analysed. These criteria, however, are only part of the consideration. Of similar importance are the content, wording of questions and answers in each of the six questionnaires and an analysis of the different score results. The issue of score bias is discussed and suggestions are given in order to increase the construct validity in the practical use of the individual questionnaires.

The value of electromyography of the lumbar paraspinal muscles in discriminating between chronic-low-back-pain sufferers and normal subjects.

The authors studied the surface electromyographic (EMG) spectrum of the paraspinal muscles of 350 subjects. They were classified by their history as normal (n=175), chronic low back pain (n=145), or past history (n=30). They pulled upwards on a floor-mounted load cell at two-thirds of their maximum voluntary contraction for 30 s, while the EMG was measured from the paraspinal muscles at the L4/L5 level. From the EMG signal the root-mean-square (RMS) was calculated. Power spectrum analysis allowed calculation of the median frequency slope, the initial median frequency (IMF), modal frequency, peak amplitude and spectral width at half peak amplitude (half-width). All of the variables of the chronic group were significantly different from the normal group, except the median frequency slope, RMS slope and mode. Half-width, age and maximum voluntary contraction were shown to be independent predictors of back pain classification. Half-width classified the subjects with a sensitivity of 0.65 and a specificity of 0.75.

The reliability of the Low Back Outcome Score for back pain.

STUDY DESIGN: A prospective test-retest study was conducted to investigate both new and follow-up patients with low back pain presenting to an orthopedic surgeon specializing in back pain. OBJECTIVES: To further validate the internal consistency and test-retest reliability of the Low Back Outcome Score, and to compare these results with other condition-specific disability scales. SUMMARY OF BACKGROUND DATA: To be useful in clinical practice, health-specific questionnaires must demonstrate reliability and validity. Several disease-specific questionnaires for low back pain have been validated to different extents. METHODS: In this study, 102 new and 42 follow-up patients consecutively attending a consultant clinic completed the Low Back Outcome Score on their visit, then again after an interval of 1 week in postal form. This instrument also was completed by 230 patients presenting to a physiotherapist. RESULTS: A response rate of 90% was achieved for the postal questionnaire. A test of internal consistency conducted with the study sample achieved a Cronbach alpha coefficient of 0.85. Overall agreement for test-retest reliability was 84%, and the reliability coefficient (K) reached a range of 0.51 to 0.86 (P < 0.05). A Bland/Altman plot was calculated, demonstrating that only 5% of patient scores change by more than 11.6 scale points between test and retest, which is not sufficient to change outcome categories. CONCLUSION: The Low Back Outcome Score appears to have good internal consistency and test-retest reliability for use in clinical practice.