November 7, 2011 (Chicago, Illinois) — Postmenopausal women with osteoarthritis of the knee have a 21% greater risk for fractures and a 27% greater risk for falls than similarly aged women without osteoarthritis, according to research presented here at the American College of Rheumatology 2011 Annual Meeting.
Researchers used data from the Global Longitudinal Study of Osteoporosis in Women (GLOW) — a prospective, multinational, observational cohort study in which more than 50,000 women submit detailed health information each year — to evaluate the risk for fractures in women with osteoarthritis.
The study was launched after several small studies reported a greater risk for fractures in this population, despite the fact that such women tend to have larger bones and less evidence of low bone mineral density than women without osteoarthritis, said lead author Daniel Prieto-Alhambra, MD, PhD, from Hospital del Mar/IMIM in Barcelona, Spain.
Approximately 20,000 women (mean age, 68 years) reported a diagnosis of osteoarthritis, which was approximately 40% of those in the database. The unadjusted hazard ratio (HR) for fracture was 1.40 (95% confidence interval [CI], 1.32 to 1.48; P < .0001) for women with osteoarthritis, compared with women without osteoarthritis. After adjustment for age and other risk factors, the risk for fracture decreased to a still significant 21% (HR, 1.21; 95% CI, 1.13 to 1.30; P < .0001). Women with osteoarthritis were also 27% more likely to have experienced a fall (adjusted HR, 1.27; 95% CI, 1.23 to 1.30; P < .0001), an association that remained significant even after adjustment for baseline falls (HR, 1.16; 95% CI, 1.08 to 1.25; P < .0001).
The fractures were unlikely to be related to osteoporosis, said Dr. Prieto-Alhambra, because the researchers controlled for the condition in their study. Instead, the severity of the fall and the way the women fell, likely the result of poor body mechanics and excess weight, probably contributed to the fractures.
"We propose that strategies to prevent falls in this population may prevent fractures," said Dr. Prieto-Alhambra. These include assessing an individual's environment for fall risks, such as throw rugs, slippery floors, and clutter. Bright lighting, night lights in the bedroom and bathroom, and placing furniture to create a clear path through rooms can also reduce falls. In addition, Dr. Prieto-Alhambra recommended studies to evaluate the potential benefits of antiosteoporotic medication in this population. Indeed, he and his team published a study earlier this year in which bisphosphonate use in women with osteoarthritis who underwent a total hip replacement significantly reduced the risk for fracture after surgery (Arthritis Rheum. 2011;63:992-1001).
"The message is that bone mineral density is falsely reassuring," said coauthor Nigel K. Arden, from the University of Oxford, United Kingdom. Dr. Arden has conducted other research demonstrating a high fracture risk in women with osteoarthritis who also have normal bone mineral density (Arthritis Rheum. 1999;42:1378-1385).
"What it really means is that we are obliged to talk to patients about home safety and functional limitations and activities of daily living," said Eric L. Matteson, MD, chair of the Department of rheumatology at the Mayo Clinic in Rochester, Minnesota. "We talk about osteoarthritis in terms of weight loss and improving general strength, but we don't do enough counseling of patients about falling."
Dr. Arden reports relationships with Merck, MSD, Roche, Novartis, Smith and Nephew, Q-MED, Nicox, Servier, Schering-Plough, Pfizer, and Rottapharm.
American College of Rheumatology (ACR) 2011 Annual Meeting: Abstract 829. Presented November 6, 2011.
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