Research Review By Dr. Paul S. Nolet©

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Date Posted:

May 2012

Study Title:

The association between a lifetime history of a work-related neck injury and future neck pain: A population based cohort study

Authors:

Nolet PS, Côté P, JD Cassidy, Carroll LJ.

Author's Affiliations:

Canadian Memorial Chiropractic College, Toronto; University of Toronto; University of Alberta, Canada

Publication Information:

Journal of Manipulative and Physiological Therapeutics 2011; 34: 348-355.

Background Information:

Neck injury and future neck pain is a controversial topic in both clinical practice and in the medical literature. Clinicians are often faced with this question in practice when a patient asks if their current neck pain could be related to their neck injury several years prior. This is a complex issue and there are not many risk studies from the general population to help answer this question. Many studies are cross-sectional in nature and cannot address issues of temporality – that is: Did the injury precede the neck pain?

The Bone and Joint Task Force on Neck Pain and Its Associated Disorders (2000-2010) found that neck pain in workers had diverse risk factors such as age, previous musculoskeletal pain, high demand jobs, low social support, job insecurity, low physical capacity, poor job satisfaction, working in awkward positions, poor physical work environment and the worker’s ethnicity (1).

Two cohort studies from the general population have examined the association between neck injuries and future episodes of neck pain. In 2001, Croft et al. (2) followed 3034 adults without neck pain and found that a history of neck injury was associated with an episode of neck pain a year later (risk ratio, 1.7; 95% CI, 1.2-2.5). In 2010, Nolet et al. (3) published the results of a cohort study of 919 individuals from Saskatchewan who reported no or mild neck pain at baseline. Those who reported a prior history of a neck injury in a motor vehicle collision were about twice as likely to develop an episode of troublesome neck pain compared to those without a history of neck injury in a motor vehicle collision (adjusted HRR = 2.14; 95% CI 1.12-4.10). To date, very little is known about the association between a prior history of a work-related neck injury.

Pertinent Results:

We studied 866 individuals with no or mild neck pain and followed them for one year to determine the association between a history of work-related neck injury and future troublesome neck pain. Ninety seven subjects reported a prior work-related neck injury. We found a positive crude association between a history of work-related neck injury and the development of troublesome neck pain (HRR = 2.3; 95% CI 1.2-4.3). Age and gender did not confound this association (adjusted HRR = 2.4; 95% CI 1.3-4.7).

Clinical Application & Conclusions:

This study provides clinicians with evidence that a past work-related neck injury may have a significant role in the development of future episodes of troublesome neck pain and disability. This finding agrees with two population based studies published previously (2, 3).
  • Patients who report a prior history of a work-related neck injury are more than twice as likely to experience future episodes of clinically significant neck pain.
  • These findings add support to the hypothesis that prior neck injury may predispose individuals to future neck pain and disability.

Study Methods:

This study used data from the Saskatchewan Health and Back Pain Survey (1995-96). The population at risk was 866 subjects with no or mild neck pain at baseline as measured with the Chronic Pain Grade Questionnaire (grade 0 or grade I neck pain). The outcome of interest was the presence of troublesome neck pain (grade II-IV). The exposure was a self-reported prior history of a work-related neck injury. The Cox proportional hazard model was used to measure the association between a history of work-related neck injury and future troublesome neck pain while controlling for the confounding effects of age and gender. We compared baseline characteristics of responders and non-responders at follow-up to look for attrition bias.

Study Strengths / Weaknesses:

This study was a phase II risk study, according to the criteria described in the Bone & Joint Decade Task Force on Neck Pain and Its Associated Disorders (2000-2010). The strengths of this study inclouded the use of a large, prospective population-based random sample of Saskatchewan adults, a valid measure of neck pain, and controlling for the confounding effects of age and gender.

This study also had some limitations. The analysis of attrition found that a higher percentage of women responded to the follow-up survey in the group without a history of work-related neck injury, and women are more likely to report neck pain than men. It is also likely that our result may be biased by residual confounding. We chose in this study not to control for the potential confounding effects of many sociodemographic, general health and comorbidities measured in the baseline survey. Because a confounder cannot be an outcome of the work-related neck injury, we felt that it would not be appropriate to include variables such as health-related quality of life, comorbidities and general health variables such as the body mass index (BMI) in our analysis. These variables could be all be made worse as a result of the neck injury and therefore be on the causal pathway between neck injury and a future episode of troublesome neck pain. For example, a neck injury may cause a person to become less active due to pain leading to weight gain (increased BMI) which then leads to future neck pain. Therefore we only controlled for the confounding effects of age and gender which are clearly not on the causal pathway. Finally, the results may have been underestimated as our study included only subjects at baseline with no or mild neck pain. It is possible that some of the subjects excluded at baseline that had troublesome neck pain may have developed the neck pain some time between the time of the work-related neck injury and the baseline survey.

Future research should aim to understand the complex pathways related to the development of neck pain. Neck pain should continue to be researched within the biopsychosocial model of pain.

Additional References:

  1. Côté P, van der Velde G, Cassidy JD, Carroll LJ, Hogg-Johnson S, Holm LW, et al. The burden and determinants of neck pain in workers: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. Spine 2008; 33(Suppl): S60-74.
  2. Croft PR, Lewis M, Papageorgiou AC, Thomas E, Jayson MI, Macfarlane GJ, et al. Risk factors for neck pain: a longitudinal study in the general population. Pain 2001; 93: 317-25.
  3. Nolet PS, Côté P, Cassidy JD, Carroll LJ. The association between a lifetime history of a neck injury in a motor vehicle collision and future neck pain: a population based cohort study. Eur Spine J 2010; 19: 972-81.