Effect of Doxycycline on Osteoarthritis (OA) Progression

This study is a double-blind, multicenter randomized controlled trial of doxycycline on osteoarthritis (OA) progression. Our previous research suggests that doxycycline might help prevent or slow OA development by reducing breakdown of cartilage in joints. The target population is one that is at high risk for the development of bilateral knee OA: overweight middle-aged women with unilateral knee OA at baseline. We hypothesize that doxycycline will decrease the severity or rate of progression of OA. We are recruiting 432 study participants across six clinical centers and randomizing them to treatment or placebo groups (N=216/group). Participants will receive either doxycycline (treatment) or placebo for 30 months. We will use several strategies to maximize compliance with the study medications and retention of participants in the study, including a "faintness-of-heart" test, which will be used at the outset to eliminate people unlikely to comply, and use of a computerized medicine cap to provide information on compliance with the prescribed dosing regimen between visits. These strategies will permit study personnel to aim their efforts to enhance compliance at those participants who can best benefit from these efforts. The primary outcome variable is minimum joint space width (or joint space narrowing, JSN) in the medial tibiofemoral compartment of the knee that is normal at baseline. In addition, we will examine changes in an algofunctional index (WOMAC), global arthritis activity, general health status (SF-36), and use of health services in the two treatment groups.