Background: Pre-operative identification of reliable predictors of post-operative pain may lead to improved pain management strategies. We investigated the correlation between pre-operative pain, psychometric variables, response to heat stimuli and post-operative pain following a laparoscopic tubal ligation procedure.
Methods: Assessments of anxiety, mood, psychological vulnerability and pre-operative pain were made before surgery using the State-Trait Anxiety Inventory (STAI), the Hospital Anxiety Depression Scale (HADS), a psychological vulnerability test and the Short-Form McGill Pain Questionnaire (SF-MPQ), respectively. Pre-operative assessments of thermal thresholds and pain response to randomized series of heat stimuli (1 s, 44-48 degrees C) were made with quantitative sensory testing technique. Post-operative pain intensity was evaluated daily by a visual analogue scale during rest and during standardized dynamic conditions for 10 days following surgery. Univariate and multivariate regression analyses were used to construct prediction models.
Results: Fifty-nine patients completed the study. Post-operative pain was significantly correlated with pre-operative pain (SF-MPQ), heat pain perception, psychological vulnerability, STAI and HADS. In the multiple regression model pre-operative pain and heat pain perception were significant predictive factors (R=0.537-0.609).
Conclusion: The study indicates that pre-surgical pain and heat pain sensitivity are important pre-operative indicators of post-operative pain intensity, while psychological factors like vulnerability and anxiety seem to contribute to a lesser degree after laparoscopic tubal ligation. The prediction model accounted for 29-43% of the total variance in post-operative movement-related pain.