Trait characteristics of centrally sensitised people with nonspecific chronic low back pain: relationships between sensory profiles, trait anxiety‐related personality types, the extent of central sensitisation symptoms and pre‐morbid lived experiences

Central sensitisation (CS) is a pain mechanism common to many chronic musculoskeletal pain conditions, the aetiology of which remains unclear. There is a paucity of evidence observing trait characteristics of sensory sensitivity, trait anxiety and personality types in people with non‐specific chronic low back pain (NSCLBP). The aim of this thesis was to identify pre‐morbid trait characteristics in people with NSCLBP and CS and to explore their possible role in the development of CS pain. The objectives were to 1) observe the range of CS symptom scores using the Central Sensitisation Inventory (CSI), 2) identify four trait sensory profiles (Sensory Sensitive, Sensation Avoiding, Low Registration and Sensation Seeking), trait anxiety and four personality types (defensive high anxious, high anxious, repressor and low anxious), 3) investigate the relationships between these trait characteristics and the extent of CS symptoms; and 4) explore the context of pre‐morbid lived experiences in which CS pain developed in light of individual trait characteristics. An international cross‐sectional observational study using a mixed methods design was carried out, with a core quantitative study using questionnaires and a concurrent nested qualitative study using semi‐structured interviews. Results showed that in a NSCLBP population with CS predominant pain 1) there were positive correlations between the Sensory Sensitive, Sensation Avoiding and Low Registration sensory profiles and a) the extent of CS symptoms and b) high trait anxiety; 2) the extent of CS symptoms could be predicted by trait anxiety, extreme defensive high anxious personality type and the two sensory profiles with a passive adaptive response (Sensory Sensitive and Low Registration); 3) there was a significantly high prevalence of high extreme, a) Sensory Sensitive, Sensation Avoiding, Low Registration scores and the defensive high anxious personality type in the high CSI sub‐group (CSI ≥ 40); and b) Low Registration scores and repressors in the low CSI sub‐group (CSI < 40). The themes from the qualitative study exploring the pre‐morbid lived experiences of people with NSCLBP and CS were: sensitivity, developmental learning differences, trauma and personal characteristics of low confidence and control, which highlighted the context in which CS pain developed. The results of this thesis lead to a proposal that pre‐morbid contexts and characteristics of trait anxiety and sensory processing may lead to heightened sensitivity and physiological arousal to stressors, and a personality type‐dependent response. A response of attention towards, and interpretation for, threat‐related stimuli may lead to CS symptoms in people with NSCLBP and CS. A longitudinal study from a premorbid baseline is recommended to confirm the predictive role of these trait characteristics in the development of CS pain.