Table 2.

Comparison of biochemical index and BMD in different groups (AS patients were divided into groups according to different clinical factor).

AS group	n	25(OH)D (nmol/L)	ICTP (ug/L)	Lumbar spine BMD (T-score)	Hip BMD (T-score)
Gender
Male	127	56.81 ± 22.79	6.07 ± 4.05	−1.64 ± 1.24	−0.90 ± 0.94
Female	23	64.08 ± 31.90	3.84 ± 1.96**	−1.51 ± 1.69	−1.01 ± 0.86
Clinical type
AAS	134	58.90 ± 25.19	5.27 ± 3.65	−1.58 ± 1.35	−0.88 ± 0.90
JAS	16	49.78 ± 14.81	9.52 ± 3.79**	−1.96 ± 1.03	−1.21 ± 1.08
Disease duration
>4 y	100	58.44 ± 27.58	5.78 ± 4.05	−1.54 ± 1.36	−1.02 ± 0.91
≦4 y	50	56.88 ± 16.56	5.62 ± 3.55	−1.79 ± 1.23	−0.71 ± 0.93
HLA-B27
Positive	129	56.98 ± 25.25	5.95 ± 4.03	−1.60 ± 1.34	−0.93 ± 0.93
Negative	21	63.72 ± 17.96	4.32 ± 2.37	−1.78 ± 1.36	−0.82 ± 0.92
CRP (mg/L)
>6	109	58.00 ± 21.65	5.94 ± 3.96	−1.71 ± 1.40	−0.99 ± 0.94
≦6	41	57.72 ± 30.92	5.16 ± 3.66	−1.37 ± 1.03	−0.72 ± 0.88
25(OH)D (nmol/L)
>50	91		4.75 ± 2.23	−1.53 ± 1.35	−0.75 ± 0.86
≦50	59		7.23 ± 5.21**	−1.77 ± 1.26	−1.18 ± 0.97**
BASDAI
>4	29	50.93 ± 17.25	6.70 ± 5.47	−2.21 ± 1.42	−1.31 ± 0.86
≦4	121	59.60 ± 25.62	5.49 ± 3.38	−1.51 ± 1.27*	−0.82 ± 0.92*

Note: independent-sample t-test was used between groups.

Values are in means ± SD.

C-reactive protein (CRP), bone mineral density (BMD), Bath AS Disease Activity Index (BASDAI), 25-hydroxyvitamin D (25(OH)D); pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP).

The comparison between the two groups.

^∗Statistically significant correlation P < 0.05.

^∗∗Statistically significant correlation P < 0.01.