[Association between serum copper concentration and hypertension in knee osteoarthritis patients]

To examine the association between serum copper concentration and the prevalence of hypertension in patients with knee osteoarthritis (OA).
 Methods: A total of 935 patients who were aged ≥40 years and underwent routine checkups from October 2013 to November 2014 at the Health Management Center of Xiangya Hospital, Central South University were included. They were diagnosed as knee OA by weight-bearing bilateral anteroposterior radiography. Serum copper concentration was measured using the chemiluminescence method. Blood pressure was measured by an electronic sphygmomanometer. The association between serum copper concentration and hypertension was evaluated by conducting multivariable adjusted logistic regression.
 Results: Compared with the lowest quintile, the multivariable-adjusted odds ratio (OR) and related 95% confidence interval (95% CI) of hypertension were 1.46 (95% CI 1.02 to 2.09, P for trend=0.035) and 1.47 (95% CI 0.77 to 2.78, P for trend=0.032) in the total population and female subgroup of the highestest quintile, respectively. There was no significant association between serum copper and hypertension in male subgroup among OA patients (OR=1.21, 95% CI 0.76 to 1.93, P for trend=0.354).
 Conclusion: The serum copper concentration was significantly associated with the prevalence of hypertension in total population and female subgroup, but may not in male subgroup among patients with knee OA.