Utility of the Psychache Scale in Patients Undergoing Surgery for Degenerative Lumbar Disease

Introduction: The impact of mental health in patients with lumbar and thoracolumbar disease has been well studied. However, psychological pain is a distinct concept that has not been evaluated in detail in the spine surgery population. This study aims to psychometrically validate the Psychache Scale (PAS) and investigate its prognostic value in predicting postoperative outcomes.

Methods: Our study is a secondary analysis of a prospective single-center study. Adults aged 21 to 85 undergoing lumbar or thoracolumbar surgery were recruited. Participants completed PAS preoperatively and other patient-reported outcome measures (PROMs) evaluating mental health, pain, physical function, and disability preoperatively and at one and six months postoperatively. PAS internal consistency was evaluated by Cronbach's alpha coefficient, and factor structure was evaluated using confirmatory factor analysis. Construct validity was assessed by examining correlations between PAS and measures of mental and physical health. The prognostic utility of PAS was evaluated by assessing its association with short- and longer-term surgical outcomes.

Results: We included 166 patients. Mean (SD) age was 59.7 (12) years, with 55% females. PAS reliability was high (Cronbach’s alpha = 0.95), and factor analysis confirmed the hypothesized one-factor structure. PAS showed strong associations with PHQ-9 (r=0.64), PROMIS anxiety (r=0.64), and pain catastrophizing scores (r=0.7), and weak to moderate correlations with non-mental health-related metrics (0.07 < r < 0.44). Preoperative PAS was moderately correlated with one-month pain interference, and six-month PHQ-9 and PROMIS anxiety scores. In predicting outcomes, the addition of PAS to models including baseline values improved the prediction of all outcomes except for PROMIS physical function.

Conclusion : Our study suggests PAS may be a valuable tool for assessing psychological distress in patients with lumbar and thoracolumbar disease. Further research is needed to fully understand its relevance in spine surgery research and practice.