Histoire naturelle de l’arthrose des membres inférieurs. Que nous a appris la cohorte KHOALA ?

The KHOALA (Knee and Hip OsteoArthritis Long term Assessment) cohort is a multi-regional cohort of 878 subjects with symptomatic knee and/or hip OA, representative of the general population, constituted from 2007 to 2009. It provides an accurate phenotyping of patients to study the evolution and predictive factors of OA. The evolution of hip and/or knee osteoarthritis is stable for the vast majority of patients and no groups have been identified that include patients showing rapid progression of osteoarthritis. These results are consistent with those of studies in the literature. However, 16 % of the patients included in the KHOALA cohort underwent arthroplasty at 5 years. This proportion is not negligible and still reflects some progression of osteoarthritis in these patients. The stability of the clinical trajectories found in our studies and in the literature could be explained by the fact that annual measurements may not be sufficient to reveal significant fluctuations. Quarterly or semi-annual measurements could therefore highlight the occurrence of relapses more easily, which could indicate a worsening of the disease. It is also the persistence of pain or reduced functional capacity that could play a major role in the decision regarding hip or knee replacement surgery. Finally, these subjects whose progression is substantial may not belong to a sufficiently large, and therefore, easily identifiable subgroup. Patients with the most severe symptoms were more likely to be female, elderly, have a high body mass index, a high Kellgren & Lawrence stage, engage in low-intensity physical activity (PA), experience significant psychosocial distress and have a low vitality score. The impact of PA is modest in the cohort. It is the intensity and type of PA (weight-bearing activities or not) at inclusion that has an impact on physical function scores at 5 years. This effect is not mediated by body composition. The impact of co-morbidities in the clinical course is significant and is well reflected by its impact in the health care consumption of patients followed for osteoarthritis. The cohort, because it offers an accurate phenotyping of patients with a large and representative number of OA subjects in the general population, is a powerful means of studying the evolution of OA and its predictive factors.