A longitudinal study

Walton DM, et al.
Arch Phys Med Rehabil. 2013 Sep 18. pii: S0003-9993(13)00909-X. doi: 10.1016/j.apmr.2013.09.004. [Epub ahead of print]

Abstract
OBJECTIVE: To investigate the short-term trajectory of recovery from mechanical neck pain, and predictors of trajectory.

DESIGN: Prospective longitudinal cohort study with 5 repeated measurements over 4 weeks.

SETTING: Community-based physiotherapy clinics in Canada.

PARTICIPANTS: Convenience sample of community-dwelling adults (N=50) with non-complicated mechanical neck disorders of any duration.

INTERVENTIONS: Usual physiotherapy care.

MAIN OUTCOME MEASURES: Neck Disability Index (NDI), Numeric Rating Scale of pain intensity (NRS).

RESULTS: A total of 50 consecutive subjects provided 5 data points over 4 weeks. Exploratory modeling using latent class growth analysis revealed a linear trend in improvement, at a mean of 1.5 NDI point and 0.5 NRS points per week. Within the NDI trajectory, 3 latent classes were identified each with a unique trend: worsening (14.5%), rapid improvement (19.6%) and slow improvement (65.8%). Within the NRS trajectory 2 unique trends were identified: stable (48.0%) and improving (52.0%). Predictors of trajectory class suggest that it may be possible to predict the trajectory. Results are described in light of the sample size.

CONCLUSIONS: The mean trajectory of improvement in neck pain adequately fits a linear model and suggests slow but stable improvement over the short term. However, up to 3 different trajectories have been identified which suggest neck pain, and recovery thereof, is not homogenous. This may hold value for design of clinical trials.

Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

PubMed Abstract:  http://www.ncbi.nlm.nih.gov/m/pubmed/24055783/