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

ArticleinAmerican Journal of Epidemiology 163(8):754-61 · May 2006with18 Reads
DOI: 10.1093/aje/kwj100 · Source: PubMed
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; NCT01539863, February 22, 2012.
    Full-text · Article · Dec 2016
    • "The determinant characteristics for cluster membership were pain intensity and disability at baseline as well as pain reduction during the first week, which were used for the development of a clinical rule to predict unfavorable recovery. This study did not reveal a separate cluster with fluctuating pain, which is in contrast to other studies in the field.[6,[8][9][10]20] The homogeneity of the patient population established by the rigorous inclusion criteria of the present study might explain this difference, as previous episodes were the main distinction criterion between fluctuating pain and rapid recovery.[10] "
    [Show abstract] [Hide abstract] ABSTRACT: Purpose: To identify recovery patterns in patients with a first episode of acute low back pain (LBP) and to define risk factors for unfavorable outcome. Methods: One hundred and eight patients (55 male, 53 female; mean age = 40.8, SD 14.2 years) rated pain (NRS) and disability [Oswestry Disability Index (ODI)] before the first treatment and 1 week, 1, 3, 6, and 12 months later. Hierarchical cluster analysis identified recovery patterns based on NRS data. Clusters were compared for age, NRS and ODI at baseline, pain reduction in the first week, gender, radicular signs and traumatic onset using one-way ANOVA (post hoc Bonferroni) and χ² tests. Results: The cluster analysis revealed four clusters: moderate baseline pain/fast recovery; high baseline pain/fast recovery; high baseline pain/persistent mild pain; high baseline pain/persistent high pain. These clusters differed in baseline NRS [F(3,104) = 39.61, p < 0.001], baseline ODI [F(3,104) = 12.17, p < 0.001], pain reduction in the first week [F(3,104) = 11.51, p < 0.001] and in radicular signs [χ²(3) = 9.20, p = 0.027]. Conclusions: These results suggest that an initial and regularly repeated assessment of pain intensity and functional disability is important. Initial pain intensity does not seem to be a prognostic factor per se, as it did not negatively affect recovery provided that it decreased early in treatment. • Implications for Rehabilitation • Prediction of outcome is particularly important in patients with a first episode of acute LBP as one third did not completely recover. • Pain intensity and functional disability should be initially assessed and regularly repeated in the first phase of treatment. • High initial pain intensity and disability combined with small pain reduction during the first week might predict unfavorable outcome and require adequate treatment.
    Full-text · Article · Oct 2016
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