Effect of Transcutaneous Electrical Nerve Stimulation on Multidimensional Pain Outcomes After Thoracic Surgery: A Secondary Analysis of a Randomized Controlled Trial.

Background and Objectives: Postoperative pain after thoracic surgery is a multidimensional experience that includes both sensory, evaluative, and affective components. While transcutaneous electrical nerve stimulation (TENS) has demonstrated benefits for postoperative pain management, its association with affective pain outcomes remains less explored. This study aimed to explore the affective dimension of postoperative pain through a secondary analysis of data from a previously conducted randomized controlled trial. Materials and Methods: Data were derived from a randomized controlled trial investigating the effects of TENS on postoperative recovery after thoracic surgery. A total of 109 patients were included and allocated into three groups: experimental (TENS + physiotherapy, n = 37), placebo (sham TENS + physiotherapy, n = 37), and control (physiotherapy alone, n = 35). The main outcome of interest in this exploratory secondary analysis was the affective dimension of pain, assessed using the Pain Rating Index-Affective (PRI-A) subscale of the McGill Pain Questionnaire before and after the 3-week rehabilitation program. Results: Improvements were observed across several pain-related variables during the intervention period. For the affective dimension of pain, the experimental group demonstrated greater reduction in PRI-A scores than the placebo and control groups. The mean reduction in PRI-A was 0.97 in the experimental group, compared to 0.27 in the placebo group and 0.57 in the control group (p < 0.0001). Between-group comparisons showed moderate to large standardized effect sizes favoring the experimental group, although the absolute magnitude of PRI-A changes was modest. Conclusions: This secondary exploratory analysis suggests that TENS combined with physiotherapy may contribute to improvements in the affective dimension of postoperative pain following thoracic surgery. These findings support further investigation of multidimensional pain outcomes within postoperative rehabilitation settings.