Time Course and Risk Profile of Work-Related Neck Disability: A Longitudinal Latent Class Growth Analysis

Abstract

Objective: Given the economic burden of work-related neck pain and disability, it is important to understand its time course and associated risk factors to direct better management strategies. This study aimed to identify the 1-year trajectories of work-related neck disability in a high-risk occupation group such as sonography and to investigate which baseline biopsychosocial factors are associated with the identified trajectories.

Methods: A longitudinal study was conducted among 92 sonographers with neck disability assessed at 3 time points-baseline, 6 months, and 12 months-using the Neck Disability Index. Baseline biopsychosocial measures included individual characteristics (demographics and physical activity levels), work-related physical and psychosocial factors (eg, ergonomic risk, workplace social support, job satisfaction), general psychological features (depression, anxiety, pain catastrophizing, and fear-avoidance beliefs), and quantitative sensory testing of somatosensory function (cold and pressure pain thresholds at neck and tibialis anterior, and temporal summation).

Results: Two distinct trajectories of neck disability were identified, including a "low-resolving disability" trajectory showing slow improvement toward no disability (64.8%) and a "moderate-fluctuating disability" trajectory characterized by persistent moderate disability with a small fluctuation across time (35.2%). The trajectory of moderate-fluctuating disability was associated with more severe symptoms, lower vigorous physical activity, higher ergonomic risk, remote cold hyperalgesia, widespread mechanical hyperalgesia, heightened pain facilitation, and several psychosocial factors such as anxiety, depression, lower job satisfaction, and lower workplace social support at baseline.

Conclusion: Over one-third of sonographers were at risk of developing a moderate-fluctuating disability trajectory. This unfavorable trajectory was associated with low physical activity level, poor ergonomics, psychosocial distress, and central sensitization at baseline.

Impact: This study has important implications for the management of neck disability in workers. Addressing modifiable factors including low vigorous physical activity, poor ergonomics, anxiety, depression, and lack of workplace social support may improve the trajectory of work-related neck disability.

Keywords: Biopsychosocial Risk; Central Sensitization; Disability Trajectory; Neck Pain; Prospective Study; Quantitative Sensory Testing.

Figure

Identified trajectories of neck disability as measured with the Neck Disability Index (NDI). The y-axis represents NDI scores, and the x-axis represents the 3 time points over 12 months. The red and green lines represent individual trajectories within class 1 (low-resolving disability) and class 2 (moderate-fluctuating disability), respectively. The black line within each class represents the mean trajectories.