Sub-grouping patients with non-specific low back pain based on cluster analysis of discriminatory clinical items

OBJECTIVE

To identify potential subgroups amongst patients with non-specific low back pain based on a consensus list of potentially discriminatory examination items.

DESIGN

Exploratory study.

PARTICIPANTS

A convenience sample of 106 patients with non-specific low back pain (43 males, 63 females, mean age 36 years, standard deviation 15.9 years) and 7 physiotherapists.

METHODS

Based on 3 focus groups and a two-round Delphi involving 23 health professionals and a random stratified sample of 150 physiotherapists, respectively, a comprehensive examination list comprising the most "discriminatory" items was compiled. Following reliability analysis, the most reliable clinical items were assessed with a sample of patients with non-specific low back pain. K-means cluster analysis was conducted for 2-, 3- and 4-cluster options to explore for meaningful homogenous subgroups.

RESULTS

The most clinically meaningful cluster was a two-subgroup option, comprising a small group (n = 24) with more severe clinical presentation (i.e. more widespread pain, functional and sleeping problems, other symptoms, increased investigations undertaken, more severe clinical signs, etc.) and a larger less dysfunctional group (n = 80).

CONCLUSION

A number of potentially discriminatory clinical items were identified by health professionals and sub-classified, based on a sample of patients with non-specific low back pain, into two subgroups. However, further work is needed to validate this classification process.

Inter-tester reliability of discriminatory examination items for sub-classifying non-specific low back pain

OBJECTIVE

To investigate the inter-tester reliability of a non-specific low back pain examination procedure, for sub-classifying non-specific low back pain.

DESIGN

Reliability study.

PARTICIPANTS

Thirty patients with non-specific low back pain (12 males, 18 females, mean age: 27.7 years (standard deviation 10.3) and 7 physiotherapists (raters).

METHODS

Based on a health professionals' consensus via focus groups and a Delphi servey, an examination procedure was developed comprising 206 items discriminatory for non-specific low back pain, 108 of which were from the History (clinical questions) and 98 from the Physical Examination (clinical tests) section. Utilizing this procedure, each patient was examined by a blinded pair of raters.

RESULTS

Moderate to excellent agreement was obtained in 125 (61%) items (77 History and 48 Physical Examination items), 47 of which obtained substantial or excellent agreement (kappa >0.61), 37 moderate agreement (kappa between 0.41 and 0.6), and 41 excellent percentage agreements. Poor reliability (kappa < 0.41) was yielded in the remaining 81 items (31 History and 50 Physical Examination items).

CONCLUSION

Satisfactory reliability was obtained in nearly two-thirds of History and half of the Physical Examination items on a non-specific low back pain assessment list generated through consensus agreement. These findings provide clinicians and researchers with valuable information regarding which items are considered reliable and can be utilized in non-specific low back pain patient evaluation/assessment procedures, classification attempts and clinical trials.

Dorsal root ganglion neurons innervating pelvic organs in the mouse express tyrosine hydroxylase

Previous studies in rat and mouse documented that a subpopulation of dorsal root ganglion (DRG) neurons innervating non-visceral tissues express tyrosine hydroxylase (TH). Here we studied whether or not mouse DRG neurons retrogradely traced with Fast Blue (FB) from colorectum or urinary bladder also express immunohistochemically detectable TH. The lumbar sympathetic chain (LSC) and major pelvic ganglion (MPG) were included in the analysis. Previously characterized antibodies against TH, norepinephrine transporter type 1 (NET-1) and calcitonin gene-related peptide (CGRP) were used. On average, ∼14% of colorectal and ∼17% of urinary bladder DRG neurons expressed TH and spanned virtually all neuronal sizes, although more often in the medium-sized to small ranges. Also, they were more abundant in lumbosacral than thoracolumbar DRGs, and often coexpressed CGRP. We also detected several TH-immunoreactive (IR) colorectal and urinary bladder neurons in the LSC and the MPG, more frequently in the former. No NET-1-IR neurons were detected in DRGs, whereas the majority of FB-labeled, TH-IR neurons in the LSC and MPG coexpressed this marker (as did most other TH-IR neurons not labeled from the target organs). TH-IR nerve fibers were detected in all layers of the colorectum and the urinary bladder, with some also reaching the basal mucosal cells. Most TH-IR fibers in these organs lacked CGRP. Taken together, we show: (1) that a previously undescribed population of colorectal and urinary bladder DRG neurons expresses TH, often CGRP but not NET-1, suggesting the absence of a noradrenergic phenotype; and (2) that TH-IR axons/terminals in the colon or urinary bladder, naturally expected to derive from autonomic sources, could also originate from sensory neurons.