The Prospective Prognostic Value of Biopsychosocial Indices of Sensitivity to Physical Activity Among People With Back Pain

Objectives: Many people living with musculoskeletal pain conditions experience a range of negative biopsychosocial responses to physical activity, referred to as increased sensitivity to physical activity (SPA), that may undermine successful rehabilitation. This exploratory study aims to provide the first prospective analysis of the potential prognostic value of 3 biopsychosocial indices of SPA in relation to rehabilitation outcomes. This study also aimed to shed light on the cross-sectional interrelationships between these 3 biopsychosocial indices of SPA. Materials and Methods: Adults with back pain were evaluated upon starting physical therapy and then again 3 months later. The initial testing session consisted of self-reported pain-related questionnaires and assessment of activity-related changes in pressure pain thresholds (SPA-Sensory), pain intensity ratings (SPA-Pain), and situational catastrophizing (SPA-Psych). The 3-month follow-up consisted of self-reported disability and pain questionnaires. Correlational and hierarchical linear regression analyses were conducted. Results: A total of 97 participants completed both the initial visit and 3-month follow-up. The SPA-Pain index and the SPA-Psych index were significantly intercorrelated, but neither were correlated with the SPA-Sensory index. The SPA-Sensory index was not correlated with outcomes. The SPA-Pain index was correlated only with cross-sectional disability and pain outcomes. The SPA-Psych index was the only SPA index significantly correlated with outcomes both cross-sectionally and at 3-month follow-up. After controlling for baseline pain/disability and pain catastrophizing, SPA-Psych was no longer a significant prognostic factor for pain, but remained a significant prognostic factor for disability at 3-month follow-up (beta=0.272, t=2.674, P=0.008, R (2) Delta=5.60%). Discussion: This study highlights the importance of conceptualizing and measuring SPA as a biopsychosocial (rather than unidimensional) construct and points toward the added prognostic value of this construct. Implications for future research and practice are discussed.