The Osteoarthritis Prevention Study

Osteoarthritis (OA), the leading cause of disability among adults, is without a cure and is associated with significant comorbidities. OA ranks as the third most common diagnosis for hospital inpatient stays with 1.25 M per year, with the knee the most commonly affected weight-bearing joint. This study will address knee OA disease prevention in adult females because prevention of OA is preferable to treatment, females are affected at nearly twice the rate as males, and to date interventions designed to slow or stop knee OA progression have failed. Dietary weight loss, with and without exercise, has level 1 evidence of effective treatment for adults with knee OA and overweight and obesity. Reduced degenerative cartilage changes are also associated with weight loss, making it a possible preventive therapy for people at risk for knee OA. The objective of this Phase III, multi-site (Boston, MA, Chapel Hill, NC, Sydney, Australia, and Winston-Salem, NC) randomized clinical trial is to establish the efficacy of an intervention of dietary weight loss, exercise, and weight-loss maintenance for knee OA prevention. We will establish efficacy in structural, symptomatic, and mechanistic outcomes compared to attention control, and determine the cost-effectiveness of this non-pharmacologic, non-surgical intervention in preventing incident knee OA in adult females aged ≥ 50 years with obesity and no or infrequent knee pain, a cohort at high risk for knee OA.

Participants will be 1,230 ambulatory, community dwelling females with obesity (BMI ≥ 30 kg/m2), and aged ≥ 50 years. Structural and symptomatic eligibility will be determined at the individual knee level. The eligible knee will have no radiographic (Kellgren Lawrence (KL) score ≤ 1) and no MRI knee OA with no or infrequent knee pain (< 15 days/month) in the same knee. The primary aim is to compare the effects of a 48-month intervention of dietary weight loss, exercise, and weight-loss maintenance to an attention control group in preventing the development of structural (MRI) knee OA using the MRI OA Knee Score (MOAKS). Secondary aims will determine the intervention effects on the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain, mobility (6 minute walk distance), and health-related quality of life (SF-36). Mechanistic secondary outcomes include knee joint compressive forces as a measure of joint loading, IL-6 as an inflammatory measure, and weight loss and exercise self-efficacy. A cost-effectiveness analysis will establish the value of the 48-month D+E (diet and exercise) intervention.

This study is significant in that it will test a critically needed primary prevention intervention of dietary weight loss, exercise, and weight-loss maintenance for females at risk for the development of knee OA designed to reduce incident structural knee OA compared to an attention control group, and intended to maximize health benefits at a reasonable cost.