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Table 3 Association between serum copper and knee chondrocalcinosis (n = 12,362)

From: Association between serum zinc and copper concentrations and copper/zinc ratio with the prevalence of knee chondrocalcinosis: a cross-sectional study

 Tertiles of serum copper (μmol/L)P for trend
1 (≤ 14.7)2 (14.8–17.5)3 (≥ 17.6)
Total
 Knee chondrocalcinosis (%)0.81.11.9
 N for knee*839081908141
 Model 1 (95% CI)1.00 (reference)1.26 (0.77, 2.05)2.01 (1.25, 3.24)0.003
 Model 2 (95% CI)1.00 (reference)1.26 (0.78, 2.06)1.94 (1.21, 3.12)0.004
 Model 3 (95% CI)1.00 (reference)1.24 (0.76, 2.02)2.00 (1.24, 3.23)0.003
 Model 4 (95% CI)1.00 (reference)1.27 (0.78, 2.07)2.11 (1.31, 3.38)0.001
 Model 5 (95% CI)1.00 (reference)1.22 (0.75, 1.99)1.95 (1.21, 3.12)0.004
Model 6 (95% CI)1.00 (reference)1.24 (0.76, 2.02)2.00 (1.24, 3.22)0.003
  1. Model 1 included age (40–49, 50–59, 60–69, ≥ 70 years), body mass index (< 28, ≥ 28 kg/m2) and sex (n = 12,362);
  2. Model 2 added serum iron (tertiles) on the basis of model 1 (n = 12,357);
  3. Model 3 added serum calcium (tertiles) on the basis of model 1 (n = 12,264);
  4. Model 4 added serum magnesium (tertiles) on the basis of model 1 (n = 12,362);
  5. Model 5 added serum zinc (tertiles) on the basis of model 1 (n = 12,362);
  6. Model 6 added serum phosphorus (tertiles) on the basis of model 1 (n = 12,264)
  7. *Three right knees with K-L 4 grade were excluded for analysis (data from the contralateral knees were retained)
  8. N, number; CI, confidence interval