What Have We Learned From Trajectory Analysis of Clinical Outcomes in Knee and Hip Osteoarthritis Before Surgery?

The past decade has seen a rapid increase in the publication of studies using trajectory analysis to describe the course of osteoarthritis (OA) symptoms. The aim of this systematic review was to describe the distinct trajectories for OA outcomes and the predictors of these trajectories.

Medline and PsycInfo databases were searched for relevant studies. Selection criteria were 1) patients ≥18 years of age, 2) patients at high risk of or diagnosed with knee or hip OA, 3) studies aiming to identify homogeneous subgroups with distinct trajectories of clinical outcomes, and 4) methodology and analysis designed to identify trajectories (longitudinal design and repeated measures). The search was limited to publications in English or French.

Of the 5,177 abstracts retrieved, 44 studies met the inclusion criteria; 21 described the disease progression before surgery. The most frequent outcomes were pain and physical function. Up to 6 trajectories of pain were found for hip and knee OA. For function, between 1 and 5 trajectories were identified for knee OA. Low educational level, high body mass index, and high number of comorbidities were the most reported predictors of bad evolution.

Although studies were heterogeneous (outcome, subgroup number, and composition), they revealed stable OA trajectories over time. This finding suggests that OA is a chronic disease that does not inevitably worsen in terms of patient-reported symptoms.