Mutifactorial analysis of risk factors for reduced bone mineral density in patients with Crohn’s disease

Table 1 Patient characteristics (means ± SD)

n	258 (166 F, 92 M)
Age (yr)	44.5 (± 11.5)
Postmenopausal women	67 (25.9%)
Fractures	28 (10.8%)
BMI (kg/m2)	24.7 (± 4.6)
Disease duration (yr)	14.3 (± 9.5)
Small bowel involvement	192 (74.4%)
Small bowel resection	135 (52.3%)
Large bowel involvement	173 (67.1%)
Current CS use	77(29.8%)
Previous CS use	152 (58.9%)
Duration CS use (mo)	51.0 (± 68.4)
Current smokers	83 (32.2%)

CS: Corticosteroids.

Table 2 Bone mineral density measurements (means ± SD)

Site	BMD(g/cm2)	Z score	T score	Osteopenia	Osteoporosis
Lumbar spine	0.975 ± 0.15	-0.308 ± 1.39	-0.795 ± 1.39	77 (29.8%)	30 (11.6%)
Total hip	0.860 ± 0.15	-0.675 ± 1.19	-1.181 ± 1.21	67 (25.9%)	35 (13.6%)

Osteopoenia defined as a T score of < -1 but > –2.5; Osteoporosis defined as a T score of < -2.5.

Table 3 Comparison of those patients with and without osteoporosis and the presence of risk factors (mean ± SD)

Risk factor	Osteoporosis atlumbar spineand/or hip( n = 47)	Osteopenia/normal bonemineral density(n = 211)	P
BMI (kg/m2)	22.3 ± 0.6	25.2 ± 0.3	< 0.0001
Corticosterid use (mo)	92.3 ± 16.7	34.9 ± 3.2	< 0.0001
Disease duration (yr)	18.9 ± 1.5	13.2 ± 0.6	< 0.005
Age (yr)	46.8 ± 11.4	44.1 ± 11.5	NS
Small bowel resection (Y/N)	10/37	105/106	NS
Current smokers (Y/N)	11/36	72/139	NS
Gender (M/F)	22/25	69/142	NS

Analysis was made using Student’s unpaired t-test or the chi-squared test where appropriate; NS: not significant.

Table 4 Biochemistry and markers of bone formation and resorption in patients with osteoporosis at either the lumbar spine and/or hip compared with those patients with osteopenia or normal bone density (mean ± SD)

Biochemistry(normal range)	Osteoporosis atlumbar spineand/or hip(n = 47)	Osteopenia/normal bonemineral density(n = 211)	P
Total calcium (2.12-2.55 mmol/L)	2.30 ± 0.03	2.31 ± 0.01	NS
Phosphate (0.65-1.3 mmol/L)	1.11 ± 0.03	1.11 ± 0.03	NS
BSAP (11.6-30.6 μg/L)	19.7 ± 1.4	18.6 ± 0.6	NS
DPD/creat (2.3-7.4 nmol/mmol)	5.8 ± 1.0	5.6 ± 0.4	NS
Ntx/creat (3.0-65.0 BCE)	63.7 ± 9.5	40.6 ± 3.6	P < 0.05

BSAP: Bone specific alkaline phosphatase; DPD: Deoxypyridinoline; Ntx: N-telopeptides of type 1 collagen; BCE: Bone collagen eqivalents; NS: not significant.

Table 5 Results of further bone biochemistry carried out in patients with a T score of -1.5 or less at either the lumbar spine and/or hip (n = 115) (mean ± SD)

Biochemistry (normal range)	T score < -1.5 at lumbarspine and/or hip (n = 115)
TSH (0.3-4.1 Mu/L)	1.7 ± 1.1
25 OHD (10-75 nmol/L)	45.1 ± 22.3
PTH (10-72 ng/L)	46.9 ± 62.7
1Testosterone (9-20 nmol/L)	13.5 ± 6.7
2FAI (> 0.3 nmol/nmol)	0.4 ± 0.1

¹Testosterone and SHBG only measured in men (n = 46).

²Free Androgen Index (Testosterone/SHBG).