Beyond numeric scales: validity of the EQ-5D-5L pain/discomfort dimension in postoperative pain assessment after minimally invasive colorectal cancer surgery

Background: This study examined the validity of the EuroQol-5 Dimension 5-Level (EQ-5D-5L) pain/discomfort dimension for acute postoperative pain assessment. Methods: This retrospective study analyzed prospectively collected data from the Korean Enhanced Recovery After Surgery (K-ERAS) registry, including adults undergoing elective minimally invasive colorectal cancer surgery at a single tertiary center between October 2023 and December 2025. Convergent validity was assessed using Spearman correlations between the EQ-5D-5L pain/discomfort dimension and numeric rating scale (NRS) scores at rest and during coughing on postoperative days (PODs) 1-3. Correlations with other EQ-5D-5L domains were compared using Steiger's Z-test. Known-group validity was evaluated by area under the curve analysis for discrimination between adjacent levels and by comparisons between ERAS and conventional groups using cumulative link mixed models. Responsiveness was assessed using standardized response means. It exhibited acceptable discriminative ability without meaningful floor or ceiling effects and responsiveness comparable to the NRS. The dimension also successfully differentiated clinical groups, with lower pain levels observed in the ERAS group. Conclusions: The EQ-5D-5L pain/discomfort dimension has potential as a valid and responsive measure for acute postoperative pain, complementing numeric scales by capturing the functional impact of pain. Further validation in diverse surgical populations is warranted.