Date

April 2009

Document Type

Dissertation

Degree Name

Ph.D.

Institution

Oregon Health & Science University

Abstract

Objectives: Emerging evidence suggests that chronic low back pain, chronic neck pain, widespread pain (WSP), and fibromyalgia (FM) share a common underlying mechanism, namely central sensitization. Research demonstrates that a majority of individuals with WSP and FM and some people with chronic low back or neck pain (termed chronic regional spinal pain, CRSP) exhibit altered pain processing which is characteristic of the neuroplastic changes of central sensitization. Perhaps due to this shared pathophysiology, recent studies have demonstrated that a subset of individuals with chronic low back or neck pain develop WSP and/or FM over time. Less clear are the specific risk factors that predispose a person with chronic low back or neck pain to the development of these widespread pain disorders. The purpose of this study was to determine the frequency with which patients with chronic low back or neck pain develop WSP or FM and to determine the risk factors which place a person at risk for this transition. Knowing the predictive factors for the development of WSP and FM in patients with CRSP is critical in that numerous studies have demonstrated that WSP and FM are associated with more severe clinical outcomes as compared to CRSP. Identifying a group of patients with CRSP who are at a higher risk of developing WSP or FM would provide an opportunity for the nursing and medical community to intervene in this downward trajectory. Methods: 2,256 patients previously seen by a multidisciplinary pain clinic in 2001 or 2002 for evaluation and treatment of a chronic low back or neck pain disorder were invited to participate in this study in 2007. The researchers used data collected on two questionnaires, one completed by the patients in 2001 or 2002 and one sent to them by the study team in 2007. Predictive factors investigated in this study fell broadly into three categories; features thought to influence the development of central sensitization, risk factors known to precede WSP and FM, and clinical features that frequently co-occur with WSP and FM. Both questionnaires included a body drawing, allowing the study team to determine which participants, who had CRSP in 2001 or 2002, had developed WSP by 2007. Those participants who had developed WSP by 2007 were invited to undergo an examination to evaluate the presence of a FM diagnosis. The 2001/2002 questionnaire was used to determine participant status on proposed risk factors prior to their development of WSP or FM. Results: Out of the 512 participants who had presented with CRSP in 2001/2002, 114 (22.3%) had developed WSP by 2007. Risk factors present in 2001/2002 that were associated with the development of WSP included moderate or severe pain intensity, female gender, history of abuse, family history of WSP, severe interference with general activity, morbid obesity, having one or more central sensitivity syndromes, and using more pain management strategies. Out of the 23.6% of subjects with WSP who were willing to report to the study site for an examination, 22 (75.9%) were diagnosed with FM. These 22 participants were added to the 18 participants who had been diagnosed with FM by their health plan provider between 2003 and 2007 for a total of 40 study participants who had presented with chronic low back or neck pain in 2001/2002 and developed FM by 2007. Risk factors present in 2001/2002 that were associated with a transition to FM included moderate or severe pain intensity, female gender, history of abuse, having a sibling with WSP, having one or more central sensitivity syndromes, and using more pain management strategies. Risk factors from 2001/2002 that did not significantly predict the development of WSP or FM in these participants with CRSP included depression, age, pain duration, number of back or neck surgeries, number of medication classes used to treat pain, tobacco pack year history, or receipt of disability benefits. Conclusions: This study demonstrated that nearly a quarter of patients with CRSP developed WSP over a six-year period. Interestingly, 75.9% if those participants who were willing to be examined also had FM. Several risk factors were shown to be predictive of the development of WSP and FM which allows practitioners to identify a group of patients with CRSP who are at increased risk for progression to a worsening clinical condition. Information gained from this study can guide the management of this group of high risk patients in an attempt to mitigate this progression. The identification of clinical features that are characteristic of this high risk group could also inform future studies that investigate individual differences in pain processing and prospective investigations into the development of other central sensitivity syndromes. Overall, this study has advanced the understanding of the relationship between CRSP, WSP, and FM in several ways.

Identifier

doi:10.6083/M4K0727Q

School

School of Nursing

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