Exploring the clinical course of neck pain in physical therapy: a longitudinal study.
OBJECTIVE
To investigate the short-term trajectory of recovery from mechanical neck pain, and predictors of trajectory.


METHODS
Prospective, longitudinal cohort study with 5 repeated measurements over 4 weeks.


METHODS
Community-based physical therapy clinics.


METHODS
Convenience sample of community-dwelling adults (N=50) with uncomplicated mechanical neck disorders of any duration.


METHODS
Usual physical therapy care.


METHODS
Neck Disability Index (NDI), numeric rating scale (NRS) of pain intensity.


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 points 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 view 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 that suggest neck pain, and recovery thereof, is not homogenous. This may hold value for the design of clinical trials.
School of Physical Therapy, Western University, London, Ontario, Canada. Electronic address: dwalton5@uwo.ca.
David M
DM
Walton
School of Physical Therapy, Western University, London, Ontario, Canada.
Yaara
Y
Eilon-Avigdor
School of Physical Therapy, Western University, London, Ontario, Canada.
Michael
M
Wonderham
Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada.
Piotr
P
Wilk
D000293:Adolescent; D000328:Adult; D002170:Canada; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000534:rehabilitation*; D010147:Pain Measurement; D026741:Physical Therapy Modalities; D016896:Treatment Outcome
BIC; BLRT; Bayesian information criterion; CI; LCGA; Longitudinal studies; NDI; NRS; Neck; Neck Disability Index; Physical therapists; Rehabilitation; TSK-11; Tampa Scale for Kinesiophobia 11-item version; bootstrapped likelihood ratio test; confidence interval; latent class growth analysis; numeric rating scale