Send Orders for Reprints to reprints@benthamscience.net The Open Orthopaedics Journal, 2014, 8, 323-330 323 1874-3250/14 2014 Bentham Open Open Access The Effect of Pressure Pain Sensitivity and Patient Factors on Self- Reported Pain-Disability in Patients with Chronic Neck Pain Zakir Uddin *,1,5,6 , Joy C MacDermid *,1,2 , Linda J. Woodhouse 3 , John J. Triano 1,4 , Victoria Galea 1 and Anita R. Gross 1 1 School of Rehabilitation Science, McMaster University, Hamilton, Ontario, Canada 2 Clinical Research Lab, Hand and Upper Limb Centre, St. Joseph’s Health Centre, London, Ontario, Canada 3 Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada 4 Research Division, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada 5 Department of Rehabilitation Science, Bangladesh University of Health Sciences, Dhaka, Bangladesh 6 Department of Physical Therapy, College of Health and Welfare, Woosong University, Daejeon, South Korea Abstract: The study was conducted to estimate the extent to which pressure pain sensitivity (PPS) and patient factors predict pain-related disability in patients with neck pain (NP), and to determine if PPS differs by gender. Forty-four participants with a moderate level of chronic NP were recruited for this cross sectional study. All participants were asked to complete self-reported assessments of pain, disability and comorbidity and then underwent PPS testing at 4-selected body locations. Pearson`s r w was computed to explore relationships between the PPS measures and the self-reported assessments. Regression models were built to identify predictors of pain and disability. An independent sample t-test was done to identify gender-related differences in PPS, pain-disability and comorbidity. In this study, greater PPS (threshold and tolerance) was significantly correlated to lower pain-disability (r = -.30 to -.53, p≤0.05). Age was not correlated with pain or disability but comorbidity was (r= 0.42-.43, p≤0.01). PPS at the 4-selected body locations was able to explain neck disability (R 2 =25-28%). Comorbidity was the strongest predictor of neck disability (R 2 =30%) and pain (R 2 =25%). Significant mean differences for gender were found in PPS, disability and comorbidity, but not in pain intensity or rating. This study suggests that PPS may play a role in outcome measures of pain and disability but between-subject comparisons should consider gender and comorbidity issues. Keywords: Comorbidity, neck pain sensitivity, neck disability, gender, pain threshold, pain tolerance. INTRODUCTION Neck pain (NP) is a common musculoskeletal pain disorder [1, 2]. Almost everyone experiences NP at some point in his or her lifetime [3] with a yearly prevalence estimated at roughly 30-50% in the general population [4-7]. Reported incidence and prevalence figures of NP may vary according to patient factors (e.g. age, gender, and comorbidity). The prevalence of pain is reportedly greater among females and older persons [5, 8]. A recent review suggested that gender can influence pain [9] and being female might be associated with higher prevalence and pain intensity. A systematic review reported that the prevalence of NP declines after middle age [10]. Another study suggests an important association between comorbidities and NP [11]. Moreover, it has been demonstrated that accumulated *Address correspondence to these authors at the School of Rehabilitation Science, McMaster University, 1400 Main Street West IAHS (4th floor), Hamilton, Ontario L8S 1C7, Canada; Tel: 1-905-525-9140, Ext. 22524; Fax: 1-905-524-0069; E-mails: zakiru@gmail.com, uddinz2@mcmaster.ca, macderj@mcmaster.ca comorbid load is independently associated with chronic pain [12]. This provides a rationale for considering patient factors, including comorbidity, in the assessment of pain- related disability in patients with chronic NP. NP and its associated disability are a tremendous financial burden to most industrialized nations [13]. The under pinning etiology of NP can be illusive [1]. Evidence suggests it is more closely associated with sensory disturbances than degenerative and radiological findings [14- 17]. A large community based British study [18] supported the importance of neurological factors in NP. Poor recovery in NP is associated with widespread sensory hypersensitivity [19, 20]. Research studies [21, 22] and a systematic review [23] have demonstrated evidence of central hyperexcitability in musculoskeletal pain. Generalized sensory hyposensitivity (hypoesthesia) and/or hypersensitivity (hyperesthesia) is a feature in a subset of chronic NP [24]. Abnormal sensory findings are prognostic of poorer clinical outcomes for chronic pain conditions [25, 24] thereby providing substantial rationale for including sensory evaluation in the assessment of patients with NP.