Multicenter Osteoarthritis Study Overview and Objectives

Osteoarthritis (OA) is the most common form of arthritis and the major cause of activity limitation and physical disability in older people, and more than half of them have radiological evidence of osteoarthritis in at least one joint. By 2030, 20 percent of Americans (about 70 million people) will have passed their 65th birthday and will be at increased risk for the disease. Today, 35 million people (13 percent of the U.S. population) are 65 and older, and more than half of development of OA.

The Multicenter Osteoarthritis Study (MOST) is a longitudinal, prospective observational study of knee osteoarthritis (OA). MOST is comprised of two clinical centers, a data coordinating center, and an analysis center.

MOST has completed three study visits: baseline and follow-up at 15 and 30 months. At each visit, clinical assessment and radiological data (x-ray and magnetic resonance) was collected.

The overall aims of MOST are to identify novel and modifiable biomechanical factors (including physical activity-related factors), bone and joint structural factors (including those assessed by MRI of the knee) and nutritional factors that affect the occurrence and progression of OA-related knee symptoms, radiographic knee OA and symptomatic knee OA, and to determine whether risk factors for new disease differ from those for progression, in a population-based cohort of men and women either with disease or at increased of developing it.

To achieve these aims, we recruited a community-based sample of 3,026 (101% of goal) men and women aged 50 to 79 drawn from the general population but selected so as to be likely to either have preexisting OA or be at high risk as indicated by overweight, knee symptoms or a history of knee injuries or operations. 15.3% of the cohort are African American and 60.1% are women. The baseline examination included an assessment of risk factors and disease characteristics, knee radiographs and knee MRIs and a musculoskeletal examination to identify knee symptoms that do not emanate from the knee or hip joint.

Baseline exams took place from 4/2003 to 4/2005. Knee MRI were acquired with a 1.0 T dedicated extremity MR scanner (OrthOne, ONI Medical Systems Inc, Wilmington, MA). Two follow-up visits were completed at 15 and 30 months. The 15-month phone contacts (with an examination, knee x-ray and MRI for 635 subjects with new knee pain and matched controls) took place from 2/2005 to 5/2006 and the 30-month exam for assessment of clinical, x-ray and MRI endpoints in all subjects occurred from 1/2006 to 11/2007. Participant retention success has been excellent, as summarized below.

Retention success in MOST (percentages do not include subjects lost to follow-up)

Subjects lost to follow-up in MOST (death or withdrew consent)

At 30-month follow-up, knee MRIs were obtained in all eligible subjects. Baseline blood and urine specimens were obtained and archived for 97.7% and 99.6% of the cohort, respectively. Blood and urine specimens were collected at 30 months in 42% of the cohort. Access to biospecimens is by submission of a MOST ancillary study proposal to the MOST Executive Committee.

Longitudinal readings of baseline, 15 month, and 30 month knee x-rays have been completed. Semiquantitative reading of selected baseline, 15 month and 30 month knee MRI have been completed.

MOST is funded through grants from the National Institutes of Health / National Institute on Aging (NIA). In late 2009 the study was funded for longitudinal follow-up for three additional time points: 60 month visit; 72 month phone contact; and 80 month visit. This rich database will provide valuable information to help identify and define modifiable biomechanical, bone and structural, nutritional, and other risk factors for new disease and progression of existing disease.

See Study Design Protocol for a description of the study plan.