Association of preoperative functional disability with chronic postsurgical pain: A prospective observational study

Background Chronic postsurgical pain negatively affects postoperative recovery. We aimed to assess the association between preoperative functional disability and chronic postsurgical pain. Methods This secondary analysis of a prospective observational study included 920 inpatients aged >= 55 years undergoing elective abdominal surgery. We assessed functional disability using the 12-item World Health Organization Disability Assessment Schedule 2.0 before surgery and measured postoperative pain using a numerical rating scale at a postanaesthetic clinic 3 months and 1 year after surgery. We performed multiple logistic regression analysis to determine associations with chronic postsurgical pain 1 year after surgery. We analysed the sequential pain score using a mixed-effects model in patients with and without preoperative functional disability. The primary outcome in this study was chronic postsurgical pain and its associated factors with a focus on preoperative functional disability. The secondary outcome was pain trajectories in patients with and without preoperative functional disability. Results Of the 899 patients included in the analysis, 11.9% had chronic postsurgical pain 1 year later. The multiple logistic regression analysis revealed that preoperative functional disability was associated with this outcome (OR 2.80, 95% CI 1.70-4.59) as well as use of preoperative pain medication (OR 2.74, 95% CI 1.24-6.03) and pain numerical rating scale at the postanaesthetic clinic (OR 1.19, 95% CI 1.10-1.29). The pain trajectories were different in the presence or absence of functional disability (p < 0.001) and the time of measurement (p < 0.001). Conclusions Preoperative functional disability was associated with chronic postsurgical pain and pain trajectories. Significance Our study showed that in patients who undergo elective abdominal surgery, 12% with preoperative functional disability experience chronic postsurgical pain after 1 year. Preoperative functional disability is associated with chronic postsurgical pain, use of preoperative pain medications and acute postoperative pain. Patients with preoperative functional disability have higher pain numerical rating scale scores at any postoperative measurement point.