Osteoarthritis (OA) of the hip is a growing problem that will continue to increase as the population ages. Previous studies have reported on risk factors for developing OA, but few have examined the factors that might predict its prognosis. A new study examined patients with hip pain to determine their disease progression and to find out how many underwent total hip replacement (THR) over the course of several years.
Led by Sita M.A. Bierma-Zeinstra and Annet M. Lievense of Erasmus Medical Center, Rotterdam, The Netherlands, the study included 227 patients who visited their general practitioners in 1996 because of hip pain. Patients were questioned about the severity of their hip pain and their general health, underwent a physical exam, had X-rays of the pelvic area and sonograms of the hip area.
Three years later, the same patients underwent follow-up, during which they were interviewed in person about the progression of their hip pain and whether or not they received a THR. In addition, their OA was assessed using the WOMAC Osteoarthritis Index. After another three years, a comparable follow-up was carried out using a survey that was mailed to the patients.
The results showed that after three years, 12 percent of the patients underwent a THR because of severe pain and/or disability due to hip OA. After six years, this number increased to 36 percent. In addition, another 3 percent to 5 percent had severe pain or disability due to the condition. Being at least 60 years old, morning stiffness, pain in the groin, restricted extension and painful rotation of the hip joint were all associated with an increased risk for undergoing THR.
The researchers note that while an earlier analysis of their data did not indicate an association between age and progression of hip pain, the current study did find the two were connected. "The difference might be attributed to selection for surgery: if a patient is relatively young, physicians tend to postpone surgery to avoid the risk of re-surgery after 10-20 years," the authors point out.
Earlier studies reported a connection between baseline hip pain and progression of OA, but the current study did not find this to be the case. The authors suggest this may be because all of the patients in their study already had hip pain. Also, obese patients tended to have a decreased risk of THR after three years, which may be attributable to the fact that these patients are typically advised to lose weight before undergoing the surgery.
"With information obtained from history taking, physical examination, and radiology, we are now better able to identify persons who are at high risk for progression of hip OA," the authors conclude. "This can be helpful not only to inform patients more precisely about the course of their hip pain, but also for future clinical trials."
Journal article: "Prognosis of Hip Pain in General Practice: A Prospective Followup Study," Annet M. Lievense, Bart W. Koes, Jan A.N. Verhaar, Arthur M. Bohnen, Sita M.A. Bierma-Zeinstra, Arthritis Care & Research, December 2007.
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