Radiographic assessment employing a Kellgren and Lawrence score at baseline is a strong predictor of progression of hip osteoarthritis (OA), particularly among patients who present with hip pain, according to a new study in the British Medical Journal.¹

Dutch researchers report that in a study of more than 1900 patients (mean age 66.2 years), a Kellgren and Lawrence score of 2 or higher identified 13.1% of subjects (odds ratio 5.8) at high risk for progression of OA of the hip. Notably, the odds ratio of hip OA progression increased substantially to 24.3 (P < 0.0001) among patients who complained of hip pain.

"The main implication is the value of an x-ray in case of the presence of hip pain," lead author Max Reijman, clinical epidemiologist at the Erasmus Medical Center in Rotterdam, The Netherlands, tells CIAOMed. "If a patient of 55 years or older visits a general practitioner because of the presence of hip pain, an additional x-ray can be rewarding [because] in combination with radiographic acetabular dysplasia, there is an increased risk of developing an incident hip OA, and secondly, in combination with radiographic evidence of hip OA, there is an increased risk of progression."

The population-based cohort study comprised 1904 men and women aged 55 years and older with the presence of visible osteoarthritic signs on radiography at baseline, defined as a Kellgren and Lawrence score >e; grade 1. In the study, radiological progression of hip OA was defined as a decrease of joint space width (>e;1.0 mm) at follow-up or the presence of a total hip replacement.

As comparative predictive models of OA progression, the researchers also used questionnaires (at-home interviews on medical history, personal demographic characteristics, risk factors for chronic diseases, use of medications, and presence of pain and morning stiffness) and detailed physical examination data (height, weight, body mass index, and external rotation, flexion, and extension of the hips).

The investigators also report that those patients with more than a 20% restriction of flexion of the hip also were at high risk of progression (odds ratio 3.1).

Identifying patients at high risk of rapid progress of OA will help stratify those in need of disease-modifying drugs. "It seems reasonable that [disease] modifying therapies will be more effective in the early stage of OA," Reijman tells CIAOMed. "Hence, the primary target group of such therapies will be those patients with hip pain combined with minimal radiographic signs of hip OA." He notes, however, "that the efficacy of structural modifying interventions needs to be investigated more thoroughly."

Reference:

Reijman M, Hazes JMW, Pols HAP, et al. Role of radiography in predicting progression of osteoarthritis of the hip: prospective cohort study. BMJ. 2005;330:1183-1188.