Hip disability and Osteoarthritis Outcome Score trajectories and prognostic factors for functional decline: A 3-year follow-up study

Background: Hip osteoarthritis (OA) can cause pain, restricted locomotor activity and functional impairments but it remains difficult to predict functional decline over time. Objectives: The aims of this study were to identify functional decline trajectories in people with hip OA using the Hip disability and Osteoarthritis Outcome Score (HOOS) domains and to determine radiological and gait predictors of typical trajectories. Methods: Consecutive people with hip OA with no indication for total hip replacement at baseline were included. Radiological, clinical (HOOS) and gait analyses were collected at baseline, and clinical follow-up was carried out every 6 months for 3 years. HOOS trajectories were estimated by group-based trajectory modeling. Predictive factors were identified by multivariate logistic regression, and their discriminatory power was assessed using the area under the ROC (receiver operating characteristic) curve. Results: Two distinct trajectories were highlighted for all HOOS domains: Traj1 (progressor) and Traj2 (nonprogressor). Using a multivariate analysis, gait speed was found to be predictive of Traj1 for HOOS symptoms/stiffness (odds ratio [OR] 0.61, 95 % CI 0.45 to 0.83, AUC (area under the curve) = 75 %) and for HOOS pain (OR = 0.72, 95 % CI 0.53 to 0.97, AUC = 72 %). Moreover, maximum hip extension was found to be predictive of Traj1 for HOOS sports and leisure (OR = 0.78, 95 % CI 0.69 to 0.89, AUC = 81 %) and HOOS quality of life (OR = 0.84, 95 % CI 0.73 to 0.95, AUC = 66%). Conclusion: This study identified 2 typical trajectories of functional decline (progressor/non-progressor) for the 5 HOOS domains. It also demonstrated the predictive validity of 2 gait parameters (gait speed and maximum hip extension) for functional decline. Database registration: NCT02042586 (c) 2024 The Authors. Published by Elsevier Masson SAS. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)