Stress Characteristics and Their Associations With Pain Intensity: An Ecological Momentary Assessment Study

This study aimed to understand the associations between stress intensity, characteristics that trigger a physiological stress responses (Sense of lack of control, social evaluative Threat, Unpredictability, Novelty; STUN) and the experience of momentary pain intensity and its variability among adults living with chronic low back pain.

Participants (n = 181) completed electronic diaries three times daily for 7 days that measured pain and stress intensity (Numeric Rating Scale-11) and the extent to which stressors were attributable to the STUN characteristics. Data was analysed using a Mixed-Effects Location Scale Model.

A 1-point increase in between-subject (BS) stress intensity was associated with a 0.70 point (p < 0.001) increase in pain intensity. For every 1-point increase in BS and within-subject (WS) perceived lack of control, pain intensity increased respectively by 0.128 and 0.040 point (p < 0.01). A 1-point increase in WS novelty was associated with a 0.05-point decrease in pain intensity (p < 0.001). There was more homogeneity in pain scores across participants at higher levels of WS stress intensity, WS perceived lack of control (β = -0.032) and BS perceived novelty (β = -0.243) (p < 0.05). Participants' own pain intensity ratings were not more or less consistent or erratic as a function of their stress levels.

Stress intensity is associated with pain intensity and with BS variance in pain ratings. STUN characteristics were inconsistently associated with pain variance, but lack of perceived control and novelty might be associated with pain intensity. Future research should clarify the role of STUN characteristics, above stress intensity, in pain intensity and pain variability.

This study advances understanding of stress-pain dynamics by applying the integrative STUN framework to chronic low back pain. Findings reveal that perceived lack of control amplifies pain, whereas novel experiences reduce it. By identifying specific stress characteristics influencing pain variability, this work highlights innovative intervention targets, emphasising the potential of fostering novelty and re-evaluating control perceptions in chronic pain management.