Pain Experience in Individuals With Chronic Low Back Pain

Low Back Pain (LBP) is considered a common condition consisting of a set of complains (pain, muscle tension, or stiffness), manifesting primarily to the lower back region (below the costal margin and above the inferior gluteal folds). LBP may or may not include radiating pain to the lower limb and can be caused by a number of underlying pathologies with varying levels of severity [1]. The condition can be the result of complex interactions between multiple physical and psychological factors including osteoarthritis (OA), degenerated discs, disc herniation, muscle dysfunction, obesity, poor posture, mental illness, negative affect (stress, anxiety, depression) [2].

LBP lifespan incidence appears to be 58-84% while it is estimated that 11% of males and 16% of females suffer from chronic LBP at any point in time [3]. It is expected that 40-50% of individuals suffering from acute LBP will continue to experience pain at three months and will demonstrate little or none further improvement, while 60-70% of those who improve will relapse within a year [4]. The global prevalence of LBP demonstrates continuously growing trends with a 17.3% increase in the last 10 years [5].

Self-management (SM) support is a portfolio of techniques and tools to help patients choose healthy behaviours as well as a fundamental transformation of the patient-caregiver relationship into a collaborative partnership [6]. Self-management support has to incorporate in its approach elements that aim to increase patients' self-efficacy, develop problem-solving, decision-making and goal-setting skills as well as to promote partner-like behaviour between patients and health professionals [7]. SM interventions pose as ideal rehabilitation strategies for chronic low back pain (CLBP) as they aim to address biological (neurophysiological, deconditioning, lifestyle) and psychosocial (self-efficacy, maladaptive beliefs, anxiety/depression) factors that have been identified as risk factors for poor outcome [8, 9] and are negatively affected by central sensitisation (CS) [10]. SM interventions are designed to be cost-effective by reducing health care utilisation associated with LBP [11].

Self-management programs (SMP) for CLBP demonstrate only small to moderate effects for long-term improvements in pain and disability. Currently, it is not known what factors predict effective self-management. Evidence of CS varies between individuals with chronic pain, and may contribute to the relatively poor efficacy of SMPs.

CS is a marker of widespread and centrally augmented pain that refers to those neurophysiological processes that can occur throughout the central nervous system (CNS) distribution, leading to changes in the spinal cord as well as in the brain [12]. The presence of CS increases the complexity of the clinical picture [13] and negatively affects a range of outcomes (e.g. pain, disability, negative affect, quality of life) following treatment [14]. CS is not present within all patients with chronic pain [15] rendering identification of those patients and decision-making for the right management approach even harder [16]. Patients with potential development of CS should receive treatment that address the full biopsychosocial clinical spectrum consisting of cognitive behavioural therapy (CBT) as well as therapeutic pain neuroscience education [17]. Changes in pain mechanisms may explain the moderate levels of evidence for the effectiveness of self-management (SM) interventions in LBP populations [7] as CS has been shown to negatively affect the perception of back pain, pain-related disability and lead to poor physical and mental health-related quality of life as well as to greater levels of depression and anxiety [10].

Quantitative Sensory Testing (QST) is a reliable [18] and valid [19] method to assess for the presence of CS and demonstrates predictive capacity in relation to musculoskeletal (MSK) treatment outcomes [20]. The testing consists of pressure pain threshold (PPT), punctate thresholds, temperature sensitivity, temporal summation (TS) and conditioned pain modulation (CPM) used to quantify noxious or innocuous stimuli within healthy individuals and patients alike [21]. QST has been used, among others, as a screening and assessment tool for sensory abnormalities in patients with pain disorders [21], as well as to assist in the stratification of patients [22] and evaluate the clinical aspects of peripheral and CS [23].

The STarT Back screening tool [24] was developed for individuals of LBP with the aim to identify prognostic indicators that could potentially assist decision making concerning initial treatment options in primary care [25]. Start Back has been formally validated, displaying satisfactory reliability, and has demonstrated that a stratified management approach displays higher health gains for patients with LBP than a non-stratified one [26]. Nevertheless, the tool's predictive performance has not been examined when other biomarkers (CS) are included as prognostic indicators.

Findings from this research will have an impact on differential diagnosis of chronic pain and CS identification as potential prognostic indicators for self-management. The results will assist effective patient subgrouping (stratification) based on CS measurements, aid appropriate self-management approaches in CLBP and potentially other chronic musculoskeletal pain states.