Predictive Validity and Patterns of Change Over Time of the Sensitivity to Pain Traumatization Scale: A Trajectory Analysis of Patients Seen by the Transitional Pain Service Up to Two Years After Surgery

Purpose: The Sensitivity to Pain Traumatization Scale (SPTS-12) was developed to assess the propensity to develop a traumatic stress response to pain. The SPTS-12 is a reliable and valid scale with a one-factor structure. The aim of the present study is to further examine the psychometric properties of the SPTS-12 by evaluating its criterion validity and how scores change over time in a sample of postsurgical patients at the Toronto General Hospital Transitional Pain Service.

Participants and methods: 361 adults (55% male; M _age = 50.6 years, SD _age = 14.3) completed questionnaires assessing symptoms of pain, anxiety, depression, and trauma at multiple visits to the Transitional Pain Service after surgery. Latent-class growth mixture modeling defined prototypical longitudinal patterns (latent trajectories) of SPTS-12 scores up to two years after surgery. One-way ANOVAs examined how trajectory classes differed over time on measures of daily opioid use (mg morphine equivalents (MME)), average pain intensity, pain interference, and depressive symptoms.

Results: The final model consisted of five SPTS-12 trajectory groups; two characterized by a flat and unchanging pattern and three showing a small but statistically significant decrease over time. Analysis of pain-related outcomes predicted by SPTS-12 trajectories provided evidence of criterion validity of the SPTS-12. SPTS-12 trajectories did not significantly differ on daily MME at any time. Average pain, pain interference, and depression scores significantly differed across SPTS-12 trajectory groups at two or more postsurgical visits (all p < 0.05).

Conclusion: The SPTS-12 shows fairly stable patterns and predicts important pain-related and psychosocial outcomes over time. Two SPTS-12 trajectories (#2 and #5) with high scores, comprising ~28% of the total sample, are associated with problematic outcomes on several pain and psychosocial measures. Targeting patients with high SPTS-12 scores for presurgical psychological treatment may prove beneficial in reducing the impact of CPSP.