Table 1.

Mean serum 25-hydroxyvitamin D (25-OHD) and proportion of serum 25-OHD deficiency^a in patients with knee osteoarthritis (OA) compared^b with controls according to age

Serum 25-OHD	All OA (n = 148) vs. controls (n = 150)	<60 years OA (n = 73) vs. controls (n = 76)	≥60 years OA (n = 75) vs. controls (n = 74)
Mean serum 25-OHD (ng/ml)	34.1 ± 32.4 vs. 38.5 ± 32.4 P = 0.28	23.8 ± 18.8 vs. 34.5 ± 29.6 P = 0.01	44.1 ± 39.2 vs. 42.8 ± 39.3 P = 0.83
Serum 25-OHD deficiency, n (%)	59 (39.8) vs. 48 (32) P = 0.18	39 (53.4) vs. 27 (35.5) P = 0.041	20 (26.6) vs. 21 (28.3) P = 0.8
OR (95% CI)	1.44 (0.89–2.3)	2.08 (1.07–4)	2.05 (0.92–4.57)

OA osteoarthritis, OR odds ratio, CI confidence interval

^a Serum 25-OHD deficiency <20 ng/ml

^b Mann-Whitney U test and chi-square test were used for comparisons of means and proportions, respectively