L. AlRashed AlHumaid1,2, D. Falla3, M. Barbero4, F. O’Shea5, F. Wilson1
1Trinity College Dublin, School of Medicine, Discipline of Physiotherapy, Dublin, Ireland, 2King Saud University, Department of Health Rehabilitation Sciences, Riyadh, Saudi Arabia, 3University of Birmingham, Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, Birmingham, United Kingdom, 4University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Rehabilitation Research Laboratory (2rLab), Department of Business Economics, Health and Social Care, Manno, Switzerland, 5St. James’s Hospital, Department of Rheumatology, Dublin, Ireland

Background: Inflammatory low back pain (ILBP) is a key clinical symptom and a significant problem in ankylosing spondylitis (AS). AS-related ILBP (AS-ILBP) prevalence is increasing among the chronic low back pain population. Yet, an initial misdiagnosis with chronic non-specific low back pain (CNSLBP) is not uncommon among individuals with AS-ILBP. This misdiagnosis has led to AS diagnostic delays which are associated with disability, poor treatment response and subsequent high socioeconomic costs. Pain among individuals with AS-ILBP is not well characterised, and the difference in pain extent (i.e. spread) and location between individuals with AS-ILBP and CNSLBP is not clear; this may influence diagnosis and add to the issue of delayed diagnosis.

Purpose: The aims of this study were:
(1) to compare pain extent and location between adults with AS-ILBP and those with CNSLBP, and
(2) to examine the relationship between pain extent and functional, psychological and condition-specific factors in those with AS-ILBP.

Methods: The pain extent and location of adults with AS-ILBP (n=27) or CNSLBP (n= 22) were objectively quantified and compared using a digital pain drawing analysis considering frontal, dorsal and lateral body regions. Relationships between pain extent and perceived LBP intensity and disability, pain-related cognitive factors (back beliefs, fear of movement, pain catastrophising, pain coping and self-efficacy), psychological distress and AS-specific features (disease activity, physical function, global well-being and quality of life) were explored in those with AS-ILBP.

Results: The extent of pain was 4.2% (IQR 4.4) of the dorsal body region in the AS-ILBP group, which was significantly greater than the CNSLBP group at 3.1% (IQR 3.3) (P < 0.05). For those with AS-ILBP, the most prevalent pain location was the lumbar region (88.9%), followed by the buttock region (70.4%); the frequencies of reported pain in these regions were similar between groups (P > 0.05). The AS-ILBP group more frequently reported pain in the thoracic (70.4%) and cervical/shoulder (51.8%) regions. In the AS-ILBP group, larger pain extent was moderately associated with more negative back beliefs (total body chart area: r = -0.44, P ˂ 0.05; dorsal body chart: r = -0.41, P ˂ 0.05), lower self-efficacy (total body chart area: r = -0.58, P ˂ 0.01; dorsal body chart: r = -0.42, P < 0.05). Larger pain extent was also associated with higher disease activity and fatigue levels (P < 0.05).

Conclusion(s): Adults with AS-ILBP perceive more spread of axial pain (i.e. spinal and buttock pain) than those with CNSLBP. In individuals with AS-ILBP, larger pain extent is associated with negative back beliefs, lower self-efficacy and higher disease activity. Larger studies investigating the difference in pain extent and location between males and females with AS-ILBP are recommended.

Implications: Pain drawings may be used to help in differentiating between AS-ILBP and CNSLBP; widespread axial pain observed on the body pain charts of CLBP patients may point to the need for a referral to rheumatology for further assessments for AS. Pain drawings may also be beneficial to advise screening of negative pain beliefs, low self-efficacy and active symptomatic state in individuals with AS-ILBP.

Funding, acknowledgements: This research was funded by a scholarship grant from King Saud University, Saudi Arabia.

Keywords: Ankylosing spondylitis-related inflammatory low back pain, Non-specific low back pain, Pain drawings

Topic: Musculoskeletal: spine

Did this work require ethics approval? Yes
Institution: Tallaght University Hospital / St. James's Hospital
Committee: Tallaght University Hospital / St. James's Hospital Joint Research Ethics Committee
Ethics number: 2017 List 33 (11)

All authors, affiliations and abstracts have been published as submitted.

Back to the listing