Psychological Factors Are Related to Pain Intensity in Back-Healthy People Who Develop Clinically Relevant Pain During Prolonged Standing: A Preliminary Study

Background: An induced-pain paradigm has been used to examine risk factors for the development of low back pain (LBP) during prolonged standing in back-healthy people (standing paradigm). Previous studies that used induced-pain methods suggest that pain intensity may be related to psychologic factors. It is not currently known, however, whether pain intensity reported during the standing paradigm is related to psychologic factors. Objective: To examine the relationship between LBP symptom intensity and psychological factors (fear of pain and pain catastrophizing) in back-healthy people who develop LBP during prolonged standing. We hypothesized that symptom intensity during standing would be positively related to initial levels of fear of pain and pain catastrophizing in people who developed LBP during standing. Design: Cross-sectional. Setting: Movement science research center at an academic medical center. Participants: Fifty seven back-healthy participants. Methods: Participants completed the Fear of Pain Questionnaire-III (FPQ-III) and Pain Catastrophizing Scale (PCS) before a 2-hour standing protocol. Participants rated LBP intensity on a 100-mm visual analogue scale (VAS) throughout standing and were classified as pain developers (PDs) or nonpain developers (NPDs). Relationships between LBP intensity and psychological measures were examined in PDs that did and did not have a >= 20 mm maximum VAS score. Main Outcome Measurements: FPQ-III and PCS total scores, maximum and average VAS scores during standing. Results: There were 24 (42%) PDs. Five PDs reported a maximum VAS score >= 20 mm. For PDs with a maximum VAS score <20 mm, correlations between average VAS scores and each psychological measure were small and nonsignificant (FPQ-III: r = 0.16, P = .50; PCS: r = 0.27, P = .26). For PDs with a maximum VAS score >= 20 mm, correlation between average VAS scores and FPQ-III was large and significant (r = 0.91, P = .03), and large for PCS but nonsignificant (r = 0.87, P = .06). Conclusion: These preliminary data suggest that if pain exceeds a clinically meaningful threshold (20 mm) during standing, pain intensity is related to psychological factors. Understanding factors that modulate acute pain response can inform early intervention strategies.