Abstract
Background It has been suggested that low back pain (LBP) is a condition with an unpredictable pattern of exacerbation, remission, and recurrence. However, there is an incomplete understanding of the course of LBP and the determinants of the course.
Objective The purposes of this study were: (1) to identify clusters of LBP patients with similar fluctuating pain patterns over time and (2) to investigate whether demographic and clinical characteristics can distinguish these clusters.
Design This study was a secondary analysis of data extracted from a randomized controlled trial.
Methods Pain scores were collected from 155 participants with chronic nonspecific LBP. Pain intensity was measured monthly over a 1-year period by mobile phone short message service. Cluster analysis was used to identify participants with similar fluctuating patterns of pain based on the pain measures collected over a year, and t tests were used to evaluate if the clusters differed in terms of baseline characteristics.
Results The cluster analysis revealed the presence of 3 main clusters. Pain was of fluctuating nature within 2 of the clusters. Out of the 155 participants, 21 (13.5%) had fluctuating pain. Baseline disability (measured with the Roland-Morris Disability Questionnaire) and treatment groups (from the initial randomized controlled trial) were significantly different in the clusters of patients with fluctuating pain when compared with the cluster of patients without fluctuating pain.
Limitations A limitation of this study was the fact that participants were undergoing treatment that may have been responsible for the rather positive prognosis observed.
Conclusions A small number of patients with fluctuating patterns of pain over time were identified. This number could increase if individuals with episodic pain are included in this fluctuating group.
Footnotes
Dr Macedo, Dr Maher, Dr Latimer, Dr McAuley, and Dr Hodges provided concept/idea/research design. Dr Macedo, Dr Maher, Dr McAuley, and Dr Hodges provided writing and data collection. Dr Macedo, Dr Maher, Dr Hodges, and Dr Rogers provided data analysis. Dr Macedo, Dr Maher, and Dr Latimer provided project management. Dr Latimer and Dr Hodges provided fund procurement. Dr Latimer provided facilities/equipment and institutional liaisons. Dr Macedo and Dr Latimer provided consultation (including review of the manuscript before submission).
The study design, procedures, and informed consent were approved by the human research ethics committees of the University of Sydney and the University of Queensland.
The original trial was funded by the Australian National Health and Medical Research Council. Dr Macedo holds a postdoctoral fellowship from the Canadian Institutes for Health Research and receives a stipend incentive from Alberta Innovates Health Solutions. Dr Latimer's and Dr Maher's research fellowships are funded by the Australian Research Council. Dr Hodges holds a research fellowship funded by the Australian National Health and Medical Research Council.
The trial was registered at the Australian New Zealand Clinical Trial Registry (ACTRN12607000432415).
- Received October 22, 2012.
- Accepted September 23, 2013.
- © 2014 American Physical Therapy Association
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