title: A prediction model for length of stay after total and unicompartmental knee replacement.
abstract: Early and accurate prediction of hospital length-of-stay (LOS) in patients undergoing knee replacement is important for economic and operational reasons. Few studies have systematically developed a multivariable model to predict LOS. We performed a retrospective cohort study of 1609 patients aged ≥ 50 years who underwent elective, primary total or unicompartmental knee replacements. Pre-operative candidate predictors included patient demographics, knee function, self-reported measures, surgical factors and discharge plans. In order to develop the model, multivariable regression with bootstrap internal validation was used. The median LOS for the sample was four days (interquartile range 4 to 5). Statistically significant predictors of longer stay included older age, greater number of comorbidities, less knee flexion range of movement, frequent feelings of being down and depressed, greater walking aid support required, total (versus unicompartmental) knee replacement, bilateral surgery, low-volume surgeon, absence of carer at home, and expectation to receive step-down care. For ease of use, these ten variables were used to construct a nomogram-based prediction model which showed adequate predictive accuracy (optimism-corrected R(2) = 0.32) and calibration. If externally validated, a prediction model using easily and routinely obtained pre-operative measures may be used to predict absolute LOS in patients following knee replacement and help to better manage these patients.
authors.affiliation: Singapore General Hospital, Department of Physiotherapy, Outram Road, Singapore 169608, Singapore.
authors.forename: P-H
authors.initials: PH
authors.lastname: Ong
authors.forename: Y-H
authors.initials: YH
authors.lastname: Pua
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D015331:Cohort Studies; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007902:Length of Stay / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology*; D012044:Regression Analysis; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012846:Singapore; D013997:Time Factors
keywords: Arthroplasty; Knee; Length of stay; Prediction modelling; TKR