Characterising the
clinical course of
back pain by mean
pain scores over time may not adequately reflect the complexity of the
clinical course of acute
low back pain. We analysed
pain scores over 12 weeks for 1585 patients with acute
low back pain presenting to primary care to identify distinct
pain trajectory groups and baseline patient characteristics associated with membership of each cluster. This was a secondary analysis of the PACE trial that evaluated
paracetamol for acute
low back pain. Latent class growth analysis determined a 5 cluster model, which comprised 567 (35.8%) patients who recovered by week 2 (cluster 1, rapid
pain recovery); 543 (34.3%) patients who recovered by week 12 (cluster 2,
pain recovery by week 12); 222 (14.0%) patients whose
pain reduced but did not recover (cluster 3, incomplete
pain recovery); 167 (10.5%) patients whose
pain initially decreased but then increased by week 12 (cluster 4, fluctuating
pain); and 86 (5.4%) patients who experienced high-level
pain for the whole 12 weeks (cluster 5, persistent high
pain). Patients with longer
pain duration were more likely to experience delayed recovery or nonrecovery. Belief in greater risk of persistence was associated with nonrecovery, but not delayed recovery. Higher
pain intensity, longer duration, and workers' compensation were associated with persistent high
pain, whereas older age and increased number of episodes were associated with fluctuating
pain. Identification of discrete
pain trajectory groups offers the potential to better manage acute
low back pain.