European Journal of Pain 2022 (Feb); 26 (2): 531–542
P Irgens, B L Myhrvold, A Kongsted, K Waagan, K B Engebretsen, N K Vøllestad, H S Robinson,
Department of Interdisciplinary Health Sciences,
Institute of Health and Society,
University of Oslo,
P.O. Box 1089,
Blindern, 0317, Oslo, Norway.
Background:   Recent studies with data-driven approaches have established common pain trajectories. It is uncertain whether these trajectory patterns are consistent over time, and if a shorter measurement period will provide accurate trajectories.
Methods   : We included 1,124 patients with non-specific neck pain in chiropractic practice. We classified patients into pre-defined trajectory patterns in each of four quarters of the follow-up year (Persistent, Episodic, and Recovery) based on measures of pain intensity and frequency from weekly SMS. We explored the shifts between patterns, and compared patients with stable and shifting patterns on baseline characteristics and clinical findings.
Results:   785 (70%) patients were in the same pattern in 1st and 4th quarter. Patients with Episodic pattern the 1st quarter shifted to other patterns more frequently than patients in the other patterns. A stable Persistent pattern was associated with reduced function and higher scores on psychosocial factors. There was a decreased frequency of patients classified as Persistent pattern (75% to 63%) and an increase of patients in Recovery pattern (4% to 15%) throughout the four quarters. The frequency of patients classified as Episodic remained relatively stable (21% to24 %).
Conclusions:   We found an overall stability of the Persistent pattern, and that Episodic patterns have more potential for shifts. Shifts mostly occurred between patterns closest in pain variation. The deviation in pattern distribution compared with previous studies suggests that the duration of measurement periods has an impact on the results of the classification.