Psychosocial, Physical, and Neurophysiological Risk Factors for Chronic Neck Pain: A Prospective Inception Cohort Study

By Jacky Au PhD, CPT

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation:

Shahidi, B., Curran-Everett, D., and Maluf, K. S. (2015). Psychosocial, physical, and neurophysiological risk factors for chronic neck pain: a prospective inception cohort study. The Journal of Pain, 16(12), 1288-1299. ABSTRACT

Introduction:

Research has demonstrated that neck pain is experienced by 30-50% of the general population (1). Although systematic reviews have identified a variety risk factors across multiple domains (2,3), consensus has yet to be reached regarding causes or contributing factors. This 12-month prospective study published in 2015 by American researchers followed 167 office workers to identify correlations between chronic neck pain (CNP) and psychosocial, physical, and neurophysiological risk factors. The study demonstrated that decreased cervical extensor endurance, diffuse noxious inhibitory control (a type of endogenous pain inhibition), and greater feelings of a depressed mood or stress increased the risk of developing CNP.

Study Summary

Study Design	Prospective Cohort
Level of Evidence	Levels of Evidence: III Evidence from prospective, observational research.
Participant Characteristics	Demographics Participants were retrospectively separated into two groups: Chronic Neck Pain (CNP): Participants who developed neck pain; as defined by a score greater than or equal to 5 on the Neck Disability Index (NDI) for 3 or more months during the 12-month study period. No CNP: A score of less than 5 for all 12 months. Chronic Neck Pain: Sample size: 35 participants Age: 29.8 +/- 6.8 years Gender: 31 females, 4 males Computer time: 33.0 +/- 8.1 hours per week No Chronic Neck Pain: Sample size: 132 participants Age: 30.2 +/- 8.3 years Gender: 102 females, 30 males Computer time: 32.7 +/- 6.4 hours per week Inclusion Criteria: New hires (within 3 months) at an office job requiring 30+ hours per week, in which at least 75% of their workday required using a computer. No reported neck pain or related disorders within the past 12-months (NDI score < 5) No current cervical pathology Exclusion Criteria: Examination revealed a structural shoulder pathology; including bursitis, impingement, tendonitis, fracture, cervical nerve/disc impairment, radiculopathy, loss of upper extremity sensory or motor function History of fibromyalgia or musculoskeletal pain in more than 4 body regions Self-reported systemic illness including cancer, rheumatic, cardiovascular, or neurological disease Previous surgery involving the cervical spine or shoulders Acute injury of the neck or shoulders within 12-weeks of study enrollment Untreated psychiatric condition Uncontrolled hypertension (>150/90 mmHg) Pregnancy Inability to type or comprehend English
Methodology	Summary Participants had a thorough initial assessment for the presence of hypothesized psychosocial, physical, and neurophysiological risk factors for CNP. Patients were than asked to resume their normal activity except for filling out a monthly version of the Neck Disability Index (NDI) Questionnaire. Initial Assessments: Psychosocial Risk Factors Depressed Mood Generalized anxiety Perceived stress Catastrophization Job satisfaction Job-related mental strain Physical Risk Factors Forward head posture Cervical active range of motion Cervical strength Cervical endurance Scapular strength Scapular muscle length Physical activity Job-related physical strain Neurophysiological Risk Factors Cold pain threshold Cold pain tolderance Pressure pain threshold Diffuse noxious inhibitory control Monthly Follow-up Assessments: Neck Disability Index (NDI) Questionnaire
Data Collection and Analysis	Data Collection Psychosocial measures were collected via the following questionnaires: Beck Depression Inventory-II Spielberger State-Trait Anxiety Index Perceived Stress Scale Pain Catastrophization Scale Minnesota Satisfaction Questionnaire (Job Satisfaction) Job Content Questionnaire-Psychological subscale (Job-related mental strain) Physical measures were largely assessed by clinical examination and are described in detail elsewhere (4). Physical activity and job-related physical strain were measured via the following questionnaires: Baecke Physical Activity Index Job Content Questionnaire-Physical Demand subscale Neurophysiological measures were tested by assessing the following: Cold pain threshold Cold pain tolerance Pressure pain threshold Diffuse noxious inhibitory control (DNIC) Data Analysis: Logistic regression analysis was used to estimate odds ratios and likelihood of each risk factor for predicting the development of CNP. Significance level was set to p ≤ 0.05 The effects of age, sex, and BMI were reduced by matching participants in the two groups. In addition to the primary analysis, several sensitivity analyses were run to test the robustness of results. Primary Analysis The dependent variable was analyzed via binary regression, and was categorized as CNP (NDI ≥ 5 for 3+ months) or (NDI < 5 for 10+ months) not CNP. Sensitivity Analysis 1 Absence of CNP was recategorized as NDI < 5 for all 12 months (n=90) Sensitivity Analysis 2 Presence of CNP was recategorized as NDI ≥ 5 for 3+ consecutive months Sensitivity Analysis 3 (12-month follow-up) Presence of CNP was recategorized as NDI ≥ 5 at month 12 only. Used to facilitate comparison with studies that only have a single end point.
Outcome Measures	Neck Disability Index (NDI) Used to define presence or absence of CNP Odds Ratio (OR) Calculated for each potential risk factor in order to predict the odds of developing CNP Interpreted as increased odds of developing CNP for each single unit increase in the potential risk factor (e.g., Odds ratio of 3.36 for depressed mood suggests 3.36 times greater odds of developing CNP for every point scored on the BDI-II).
Results	Incidence of CNP 21% (n=35) met criteria for CNP (NDI ≥ 5 for at least 3 months) Primary Results Significant risk factors with odds ratio, 95% confidence interval, and p-value: Depressed mood (OR=3.36, CI=1.1-10.31, p=0.03) Cervical extensor endurance (OR=0.92, CI=0.87-0.97, p=0.001) DNIC (OR=0.9, CI=0.83-0.98, p=0.02) Sensitivity Analysis 1 Depressed mood (OR = 8.73, CI=1.27-59.99, p=03) Cervical extensor endurance (OR=0.83, CI=0.74-0.94, p=0.002) Sensitivity Analysis 2 Perceived stress (OR=1.01, CI=1.01-1.21, p=0.03) Marginal effect of DNIC (OR = 0.89, CI=0.79-1.01, p=0.08) Sensitivity Analysis 3 (12-month follow-up) Cervical extensor endurance (OR=0.9, CI=0.86-0.96, p<0.001)
Researchers' Conclusions	Across several analyses, risk factors for developing CNP included depressed mood, decreased cervical extensor endurance, inhibited DNIC, and higher perceived stress levels. A decrease in cervical extensor endurance was the most robust effect, being exhibited by the most participants with CNP and demonstrating significance in the widest range of sensitivity analyses. However, depressed mood demonstrated the largest effect size. That is, even small increases in depression scores greatly increased the odds of developing CNP. Importantly, very few study participants scored high enough on the depression questionnaire to be suspected of clinical depression. These findings suggest that optimizing cervical function, strength, and endurance, as well as identifying changes in mood may be key interventions for the prevention and treatment of CNP.

How this Study Contributes to the Body of Research:

Previous studies (2,3) have failed to reach consensus regarding the risk factors correlated with the development of chronic neck pain (CNP). This study is one of a few published prospective studies that follows a large cohort of individuals who were all asymptomatic at baseline. Prospective studies that monitor individuals from asymptomatic at baseline to the development of CNP, are essential for identifying factors that may be addressed for prevention or treatment. Congruent with previous research, depressed mood had a large effect on pain, including modest, sub-clinical changes significantly increasing the likelihood of developing CNP. More pertinent to human movement professionals, poor cervical extensor endurance was a more robust factor, reported by more individuals in the CNP group and appearing in more of the sensitivity analyses. Future research should investigate the efficacy of addressing depressed mood and cervical extensor endurance to reduce the likelihood of developing CNP.

How the Findings Apply to Practice:

This study identified key factors that may be identified and addressed to aid in the prevention and treatment of CNP. Perhaps most pertinent to human movement professionals, a decrease in cervical extensor endurance was a correlated factor and may be assessed and treated using techniques within the scope of movement professionals. Further, human movement professionals may use outcome measure questionnaires to identify changes in mood and stress levels that may affect pain and warrant a referral to a mental health professional.

Strengths

In contrast to most similar studies, this study used an initially asymptomatic cohort, affording human movement professionals critical insight into CNP development.
This study included mechanical, psychosocial and neurophysiological measures as potential risk factors, which may provide a more complete assessment of contributing factors.
The statistical model controlled for known covariates of CNP such as age, sex, and body-mass index, which was crucial for reducing noise in heterogenous literature.

Weaknesses

The cohort consisted primarily of highly educated, white, female office workers who ended up developing relatively mild neck pain. Results of this study may not generalize to other demographics, or to the development of more severe symptoms.
Participants may have been aware of the study’s purpose, which could have induced a response bias when filling out the self-report questionnaires.
Despite the relatively large overall sample size, the subgroup analyses include much smaller samples (as few as 17 in one group), suggesting failure to refute the null or demonstrate a trend should be interpreted with knowledge the study may be underpowered.

How the Study Relates to Brookbush Institute Content?

The Brookbush Institute (BI) continues to develop and refine our library of cervical assessment and strengthening techniques, as seen in Upper Body Dysfunction (UBD). This study demonstrated the relationship between inhibited cervical extensor endurance and development of chronic neck pain (CNP). The BI has integrated this prospective study with others to add to refine our model of cervical dysfunction and recommended assessments and interventions. The BI will continue to pursue optimal practice by refining our knowledge of preventative exercises using the aggregated results of all available relevant research.

Videos:

The following videos illustrate common assessments and interventions used to address cervical dysfunction:

Cervical Extensor Self-administered Static Release

Cervical Fascia Instrument-Assisted Soft Tissue Mobilization

Cervical Spine Manipulation

Deep Cervical Flexor Activation:

Deep Cervical Flexor Progression for Range of Motion (ROM)

Additional Readings

Bibliography:

Hogg-Johnson S, van der Velde G, Carroll LJ, Holm LW, Cassidy JD, Guzman J, et al. (2009): The Burden and Determinants of Neck Pain in the General Population: Results of the Bone and Joint Decade 2000–2010 Task Force on Neck Pain and Its Associated Disorders. Journal of Manipulative and Physiological Therapeutics 32: S46–S60.
da Costa BR, Vieira ER (2010): Risk factors for work-related musculoskeletal disorders: A systematic review of recent longitudinal studies. Am J Ind Med 53: 285–323.
Paksaichol A, Janwantanakul P, Purepong N, Pensri P, Beek AJ van der (2012): Office workers’ risk factors for the development of non-specific neck pain: a systematic review of prospective cohort studies. Occup Environ Med 69: 610–618.
Shahidi B, Johnson CL, Curran-Everett D, Maluf KS (2012): Reliability and group differences in quantitative cervicothoracic measures among individuals with and without chronic neck pain. BMC Musculoskelet Disord 13: 215.
Linton SJ (2000): A review of psychological risk factors in back and neck pain. Spine (Phila Pa 1976) 25: 1148–1156.
Carroll LJ, Cassidy JD, Côté P (2004): Depression as a risk factor for onset of an episode of troublesome neck and low back pain. Pain 107: 134–139.

Questions, comments, and criticisms are welcomed and encouraged -

Psychosocial, Physical, and Neurophysiological Risk Factors for Chronic Neck Pain: A Prospective Inception Cohort Study