Knee OA Doubles Frailty Risk After Age 60


Knee osteoarthritis can trigger a series of clinical problems that set patients on the road to early frailty, especially if both knees are involved. It's prudent for their physicians to be on high alert for it.

Misra D, Felson DT, Silliman RA, et al., Knee Osteoarthritis and Frailty: Findings From the Multicenter Osteoarthritis Study and Osteoarthritis Initiative. J Gerontol A Biol Sci Med Sci. (2014) doi: 10.1093/gerona/glu102 [First published online: July 25]

People aged 60 and older who have radiographic and symptomatic knee osteoarthritis (OA) are twice as likely to become frail as people the same age without knee OA, according to the first study to examine the issue.

Knee OA can lead to a cascade of interconnected comorbidities in older people: pain and inactivity, loss of muscle mass, impaired gait, weakness, falls, and fractures. All of these can contribute to frailty, a condition that affects 4% to 17% of people after age 60, say the researchers.

Yet without a specific assessment it's easy to miss these warnings of frailty in these patients.

The data come from a cross-sectional analysis of more than 3,700 participants in two large national studies of risk factors in knee OA. They revealed a 60% greater prevalence of frailty among those who have both knees visibly affected on X-rays -- and an almost two-fold prevalence among those with symptoms in only one affected knee.

Participants in the federally-funded Multicenter Osteoarthritis Study (MOST) and the Osteoarthritis Initiative (OAI) had bilateral knee X-rays at baseline and at each study visit, as well as assessment of symptoms such as knee pain. Women made up 60% of the group, with a median age of 68 and a body mass index (BMI) of 29, just short of obesity.

FRAIL asks if patients:
• Are fatigued
• Have trouble walking a flight of steps
• Are unable to walk more than one block
• Have more than five illnesses, or
• Have lost over 5% of their body weight in the past six months.

Three "yes" answers signals frailty.

Frailty, as defined by the Study of Osteoporotic Fracture (SOF) index, includes weight loss of over 5% between two consecutive doctor visits, poor energy, and the inability the get up from a chair five times in succession without help.

By this definition, a longitudinal analysis of the study cohort found a 45% incidence of frailty among those with bilateral radiographic knee OA and 66% among those with symptomatic knee OA.

Last year, members of six international and US medical organizations recommended that all people over age 70 be screened for physical frailty  using simple tools such as the 5-item FRAIL (Fatigue, Resistance, Ambulation, Illnesses, and Loss) questionnaire. (See sidebar).

Better understanding of the newfound link between frailty and knee OA could lead to new targets for prevention and treatment, say the authors of the study, which appears online in the Journals of Gerontology: MEDICAL SCIENCES, published by the Gerontological Society of America.

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