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Ann Rheum Dis doi:10.1136/annrheumdis-2013-205012
  • Clinical and epidemiological research
  • Extended report

The relative contribution of mechanical stress and systemic processes in different types of osteoarthritis: the NEO study

  1. 1Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
  2. 2Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
  3. 3Department of Medical Statistics and Bio-informatics, Leiden University Medical Center, Leiden, The Netherlands
  4. 4Department of Endocrinology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
  5. 5Department of Thrombosis and Hemostasis, Leiden University Medical Center, Leiden, The Netherlands
  1. Correspondence to A Willemien Visser, Department of Rheumatology, Leiden University Medical Center, C1-R, P.O. Box 9600, Leiden 2300 RC, The Netherlands; a.w.visser{at}lumc.nl
  • Received 3 December 2013
  • Revised 21 March 2014
  • Accepted 1 May 2014
  • Published Online First 20 May 2014

Abstract

Objective To study the relative contribution of surrogates for mechanical stress and systemic processes with osteoarthritis (OA) in weight-bearing and non-weight-bearing joints.

Methods The Netherlands Epidemiology of Obesity study is a population-based cohort including 6673 participants (range 45–65 years, 56% women, median body mass index 26 kg/m2). Weight (kg) and fat mass (kg) were measured, fat-free mass (kg) was calculated. The metabolic syndrome was defined following the Adult Treatment Panel III criteria. Knee and hand OA were defined according to the American College of Rheumatology clinical criteria.

Logistic regression analyses were performed to associate surrogates for mechanical stress (such as weight, fat-free mass) and systemic processes (such as metabolic syndrome) with OA in knees alone, knees and hands or hands alone, adjusted for age, sex, height, smoking, education and ethnicity, and when appropriate for metabolic factors and weight.

Results Knee, knee and hand, and hand OA were present in 10%, 4% and 8% of the participants, respectively. Knee OA was associated with weight and fat-free mass, adjusted for metabolic factors (OR 1.49 (95% CI 1.32 to 1.68) and 2.05 (1.60 to 2.62), respectively). Similar results were found for OA in knees and hands (OR 1.51 (95% CI 1.29 to 1.78) and 2.17 (95% CI 1.52 to 3.10) respectively). Hand OA was associated with the metabolic syndrome, adjusted for weight (OR 1.46 (95% CI 1.06 to 2.02)).

Conclusions In knee OA, whether or not in co-occurrence with hand OA, surrogates for mechanical stress are suggested to be the most important risk factors, whereas in hand OA alone, surrogates for systemic processes are the most important risk factors.