Purpose <p>This study aims to psychometrically validate the Psychache Scale (PAS) and investigate its prognostic value in predicting postoperative outcomes.</p> Methods <p>This is a prospective single-center study. Adults undergoing lumbar or thoracolumbar surgery were recruited. Participants completed PAS preoperatively and patient-reported outcome measures 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. PAS prognostic utility was evaluated by assessing its association with short- and longer-term surgical outcomes.</p> Results <p>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 correlations with PHQ-9 (<i>r</i> = 0.64), PROMIS anxiety (<i>r</i> = 0.64), pain catastrophizing scale (PCS) (<i>r</i> = 0.7), and its helplessness (<i>r</i> = 0.72), magnification (<i>r</i> = 0.59), and rumination (<i>r</i> = 0.59) subscales. However, it shows weak to moderate correlations with non-mental health-related metrics (0.07 &lt; <i>r</i> &lt; 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.</p> Conclusions <p>Our study suggests PAS may be a valuable tool for assessing psychological distress in this patient population. Further research is needed to understand its relevance in spine surgery practice.</p> Level of Evidence <p>II.</p>