Characterizing the Course of Low Back Pain: A Latent Class Analysis

ArticleinAmerican Journal of Epidemiology 163(8):754-61 · May 2006with17 Reads
DOI: 10.1093/aje/kwj100 · Source: PubMed
Abstract
Understanding the course of back pain is important for clinicians and researchers, but analyses of longitudinal data from multiple time points are lacking. A prospective cohort study of consecutive back pain consulters from five general practices in the United Kingdom was carried out between 2001 and 2003 to identify groups defined by their pain pathways. Patients were sent monthly questionnaires for a year. Longitudinal latent class analysis was performed by using pain intensity scores for 342 consulters. Analysis yielded four clusters representing different pathways of back pain. Cluster 1 ("persistent mild"; n = 122) patients had stable, low levels of pain. Patients in cluster 2 ("recovering"; n = 104) started with mild pain, progressing quickly to no pain. Cluster 3 ("severe chronic"; n = 71) patients had permanently high pain. For patients in cluster 4 ("fluctuating"; n = 45), pain varied between mild and high levels. Distinctive patterns for each cluster were maintained throughout follow-up. Clusters showed statistically significant differences in disability, psychological status, and work absence (p < 0.001). This is the first time, to the authors' knowledge, that latent class analysis has been applied to longitudinal data on back pain patients. Identification of four distinct groups of patients improves understanding of the course of back pain and may provide a basis of classification for intervention.
    • "Low back pain (LBP) is a prevalent condition [1, 2] often with an intermittent course [3, 4] with episodic flare-ups [5, 6] and periods without pain [7, 8]. A definition of what constitutes an episode of LBP is fundamental for the study of new episodes, risk factors, resolution, persistence and recurrence [9]. "
    [Show abstract] [Hide abstract] ABSTRACT: Background: It has been proposed that an episode of low back pain (LBP) be defined as: "a period of pain in the lower back lasting for more than 24 h preceded and followed by a period of at least 1 month without LBP". Previous studies have tested the definition in the general population and in secondary care populations with distinctly different results. The objectives of this study (in a primary care population) were to investigate the prevalence of 1) the number of consecutive weeks free from bothersome LBP, 2) the prevalence of at least four consecutive weeks free from bothersome LBP at any time during the study period, and 3) the prevalence of at least four consecutive weeks free from bothersome LBP at any time during the study period among subgroups that reported >30 days or ≤30 days of LBP the preceding year. Method: In this prospective multicentre study subjects with LBP (n = 262) were consecutively recruited from chiropractic primary care clinics in Sweden. The number of days with bothersome LBP was collected through weekly automated text messages. The maximum number of weeks in a row without bothersome LBP and the number of periods of at least four consecutive weeks free from bothersome LBP was counted for each individual and analysed as proportions. Results: Data from 222 recruited subjects were analysed, of which 59 % reported at least one period of four consecutive weeks free from bothersome LBP. The number of consecutive pain free weeks ranged from 82 (at least one) to 31 % (9 or more). In subjects with a total duration of LBP of ≤ 30 days the previous year, 75 % reported a period of 4 consecutive weeks free from bothersome LBP during the study period whereas this was reported by only 48 % of subjects with a total duration of LBP of >30 days the previous year. Conclusion: Prevalence of four consecutive pain free weeks is found in the majority of subjects in this population logically reflects duration of LBP within the sample and may be applied on patients in primary care to demarcate a LBP episode.
    Full-text · Article · Dec 2016
    • "The vast majority of people will experience LBP at some point in their life and about two-thirds will experience recur- rences [4]. The individual course of LBP may follow a number of different trajectories678 and rather than the common categories of acute, sub-acute or chronic [1] LBP could be described as a long-term recurrent condition. In about 90 % of patients suffering from LBP, no underlying spinal pathology or red flags can be identified , and their LBP is classified as non-specific [4]. "
    [Show abstract] [Hide abstract] ABSTRACT: Background: To investigate if psychological and behavioral factors (as determined by the Swedish version of the West Haven-Yale Multidimensional Pain Inventory, MPI-S) can predict the early clinical course of Low Back Pain (LBP). Methods: MPI-S data from patients (18-65 years of age) seeking chiropractic care for recurrent and persistent LBP were collected at the 1st visit. A follow-up questionnaire was administered at the 4th visit. The predictive value of the MPI-S subgroups Adaptive Copers (AC), Interpersonally Distressed (ID) and Dysfunctional (DYS) was calculated against the subjective improvement at the 4th visit and clinically relevant difference in pain intensity between the 1st and 4th visit. Results: Of the 666 subjects who were included at the 1st visit, 329 completed the questionnaire at the 4th visit. A total of 64.7 % (AC), 68.0 % (ID) and 71.3 % (DYS) reported a definite improvement. The chance of "definite improvement", expressed as relative risk (95 % CI) with the AC group as reference, was 1.05 (.87-1.27) for the ID and 1.10 (.93-1.31) for the DYS groups, respectively. The DYS and ID groups reported higher values in pain intensity both at the 1st and the 4th visit. The proportion of subjects who reported an improvement in pain intensity of 30 % or more (clinically relevant) were 63.5 % AC, 72.0 % ID and 63.2 % DYS. Expressed as relative risk (95 % CI) with the AC group as reference, this corresponded to 1.26 (.91-1.76) for the ID and 1.09 (.78-1.51) for the DYS groups, respectively. Conclusions: The MPI-S instrument could not predict the early clinical course of recurrent and persistent LBP in this sample of chiropractic patients. Trial registration: Clinical trials.gov; NCT01539863, February 22, 2012.
    Full-text · Article · Dec 2016
    • "Finally, we recruited a mixed population of asymptomatic individuals classified as such since they did not report pain in the low-back within the last 7 days prior to the experiment and had no history of low back injury or/and surgery. However, pain is usually fluctuating as Is One Trial Sufficient to Obtain Excellent Pressure Pain Threshold Reliability in the Low Back? reported by recent studies [50,51,52]. Further, the present results should not be generalized to specific population or gender as gender differences are reported in pressure pain sensitivity [33,53,54]. "
    [Show abstract] [Hide abstract] ABSTRACT: The assessment of pressure pain threshold (PPT) provides a quantitative value related to the mechanical sensitivity to pain of deep structures. Although excellent reliability of PPT has been reported in numerous anatomical locations, its absolute and relative reliability in the lower back region remains to be determined. Because of the high prevalence of low back pain in the general population and because low back pain is one of the leading causes of disability in industrialized countries, assessing pressure pain thresholds over the low back is particularly of interest. The purpose of this study study was (1) to evaluate the intra- and inter- absolute and relative reliability of PPT within 14 locations covering the low back region of asymptomatic individuals and (2) to determine the number of trial required to ensure reliable PPT measurements. Fifteen asymptomatic subjects were included in this study. PPTs were assessed among 14 anatomical locations in the low back region over two sessions separated by one hour interval. For the two sessions, three PPT assessments were performed on each location. Reliability was assessed computing intraclass correlation coefficients (ICC), standard error of measurement (SEM) and minimum detectable change (MDC) for all possible combinations between trials and sessions. Bland-Altman plots were also generated to assess potential bias in the dataset. Relative reliability for both intra- and inter- session was almost perfect with ICC ranged from 0.85 to 0.99. With respect to the intra-session, no statistical difference was reported for ICCs and SEM regardless of the conducted comparisons between trials. Conversely, for inter-session, ICCs and SEM values were significantly larger when two consecutive PPT measurements were used for data analysis. No significant difference was observed for the comparison between two consecutive measurements and three measurements. Excellent relative and absolute reliabilities were reported for both intra- and inter-session. Reliable measurements can be equally achieved when using the mean of two or three consecutive PPT measurements, as usually proposed in the literature, or with only the first one. Although reliability was almost perfect regardless of the conducted comparison between PPT assessments, our results suggest using two consecutive measurements to obtain higher short term absolute reliability.
    Full-text · Article · Aug 2016
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