Metabolic syndrome not associated with knee osteoarthritis
Metabolic syndrome (MetS) or its components show no relationship with incident knee osteoarthritis (OA), although there may be an association with high blood pressure that requires further investigation, according to the results of the Framingham OA study.
The study included 991 individuals (mean age 54.2 years; 55.1 percent female). OA evaluations were conducted in 1992 to 1995 and in 2002 to 2005, while MetS component assessment was done right after the baseline visit.
Incident radiographic OA (ROA) was defined as having a Kellgren and Lawrence grade ≥2 at follow-up, whereas incident symptomatic OA (SxOA) was described as the development of the new combination of ROA and knee pain.
Binary regression analysis with generalized estimating equations was used to test the association of MetS (according to the Adult Treatment Panel III criteria) and its components with the risk of incident ROA and SxOA before and after adjustment for body mass index (BMI).
Results showed that 26.7 percent of men and 22.9 percent of women had MetS. Initially, MetS and many of its components were associated with both incident ROA and SxOA. However, these associations were substantially attenuated and became nonsignificant after controlling for BMI and body weight.
Of note, an association between high blood pressure, particularly diastolic pressure, and SxOA persisted in both men and women.
MetS ups the risk of cardiovascular disease and mortality. Its components include central obesity, dyslipidaemia, impaired fasting glucose and hypertension. Several studies have reported an association between central obesity and BMI, which is a well-known risk factor for knee OA. Other mechanisms by which MetS components may influence the occurrence of OA are low-grade inflammation, alteration of the microvasculature of subchondral bone and neuromuscular impairment. [Cardiol Res Pract 2014;2014:21; Curr Opin Rheumatol 2010;22:533-7; Rheumatology (Oxford) 2007;46:1763-8; Ann Rheum Dis 2011;70:1354-6]