Characterising Pain in Post-COVID-19 Syndrome: An Observational Study of Intensity and Sensitivity

Background/Objectives: Post-COVID-19 syndrome (PCS) is frequently accompanied by pain, which may coexist with alterations in multiple health domains. However, pain in PCS has rarely been explored from a multidimensional approach combining subjective and objective measures. Objective: To describe pain in subjects with PCS using pain intensity and the pressure pain threshold (PPT), and to examine the associations between these measures and descriptive characteristics as well as health status. Methods: A cross-sectional observational study was conducted in 45 previously hospitalised adults with PCS. Pain intensity was assessed using the visual analogue scale and PPT was assessed by algometry. Health status included fatigue, dyspnoea, anxiety, depression, quality of life, functionality, frailty, physical activity, muscle quality, muscle strength, physical performance, and functional capacity. Analyses were conducted using SPSS v30.0. Results: Participants showed moderate pain intensity and variability in PPT, with a significant inverse association between both measures. Bivariate analyses showed that higher pain intensity and lower PPT were associated with worse physical, psychological, and functional outcomes. In regression analyses, pain intensity was associated with sex, length of hospital stay, PPT, and quality of life; PPT was associated with sex, pain intensity, and grip strength. Model explanatory capacity varied, and some models were not statistically significant. Conclusions: Subjects with PCS exhibited moderate pain intensity and variability in pain sensitivity, with an association between subjective and objective pain measures. Pain measures were associated with multiple health domains at the bivariate level, while regression analyses identified a limited number of associations with variable explanatory capacity. These findings support comprehensive pain assessment in PCS.