Pain catastrophising as a risk factor for hospitalisation and readmissions in fast-track hip and knee arthroplasty, an observational multicentre cohort study

Background A preoperative pain catastrophising scale (PCS) of >20 is associated with increased postoperative pain, development of chronic pain, and impaired function after hip and knee arthroplasty. However, whether PCS >20 is associated with prolonged length of hospital stay (LOS), readmissions, and reduced likelihood of same-day discharge is unknown.The primary aim of this study was to investigate the association between a preoperative PCS of >20 and a LOS >2 days Secondary aims were to investigate the association of PCS >20 with 90-day readmission rate and admission postoperatively. Methods This prospective cohort study is from eight Danish arthroplasty departments with similar fast-track protocols. Data on preoperative PCS, patient characteristics, and prescribed medications were collected. Postoperative follow-up was conducted through patient records and self-reported questionnaires. Binary multilevel logistic regression was used to investigate the association between PCS >20 and hospital LOS of >2 days, 90-day readmission rate due to pain or insufficient mobilisation, and immediate admission despite scheduled same-day surgery. Results The study period ran from September 2022 to June 2025. Of 15 965 procedures, 6728 (43%) were total hip arthroplasties (THA), 5992 (38%) were total knee arthroplasties (TKA), and 2974 (19%) were unicompartmental knee arthroplasties (UKA). Of these, 5225 (33%) reported a preoperative PCS >20. Median hospital LOS was 1 day, 90-day readmission rate was 7.3%, and 5464 (35%) of patients were scheduled for same-day discharge. For the total cohort, PCS > 20 was associated with LOS >2 days (odds ratio [OR]: 1.54; 95% confidence interval [CI]: 1.29–1.83; P <0.001), 90-day all-cause readmissions (OR: 1.18; CI:1.03–1.35; P =0.02), hospitalisation due to pain or insufficient mobilisation (OR: 1.38; CI: 1.11–1.72; P =0.004), and admission despite planned same-day discharge (OR: 1.25; CI: 1.06–1.40; P =0.005). However, procedure-specific analysis did not find associations with LOS after UKA (OR: 0.59; CI: 0.30–1.17; P =0.129), or readmission after TKA (OR: 1.02; CI: 0.82–1.26; P =0.890). Conclusions A preoperative pain catastrophising scale of >20 was associated with increased hospital length of stay and increased 90 day readmission rate despite planned same-day discharge after fast-track total hip arthoplasty, total knee arthoplasty and unicompartmental knee arthroplasty surgery.