Pain catastrophizing, physiological indexes, and chronic pain severity: tests of mediation and moderation models.

Catastrophizing about pain is related to elevated pain severity and poor adjustment among chronic pain patients, but few physiological mechanisms by which pain catastrophizing maintains and exacerbates pain have been explored. We hypothesized that resting levels of lower paraspinal muscle tension and/or lower paraspinal and cardiovascular reactivity to emotional arousal may: (a) mediate links between pain catastrophizing and chronic pain intensity; (b) moderate these links such that only patients described by certain combinations of pain catastrophizing and physiological indexes would report pronounced chronic pain. Chronic low back pain patients (N = 97) participated in anger recall and sadness recall interviews while lower paraspinal and trapezius EMG and systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were recorded. Mediation models were not supported. However, pain catastrophizing significantly interacted with resting lower paraspinal muscle tension to predict pain severity such that high catastrophizers with high resting lower paraspinal tension reported the greatest pain. Pain catastrophizing also interacted with SBP, DBP and HR reactivity to affect pain such that high catastrophizers who showed low cardiovascular reactivity to the interviews reported the greatest pain. Results support a multi-variable profile approach to identifying pain catastrophizers at greatest risk for pain severity by virtue of resting muscle tension and cardiovascular stress function.