The relation of hand skin-fold thickness to bone mineral density in patients with Crohn's disease.

OBJECTIVES

In healthy postmenopausal women, the association of skin-fold thickness (SFT) with bone mineral density (BMD) is well described, and a low SFT is a useful predictor of osteoporosis. In this study the association between hand SFT and BMD in patients with Crohn's disease was assessed; and the potential for hand SFT as a screening test for osteoporosis evaluated.

DESIGN/

METHODS

In a cross-sectional study, BMD was measured at the hip and lumbar spine by dual energy x-ray absorptiometry (DEXA). SFT was measured on the dorsum of the right hand using Holtain Tanner Whitehouse calipers. One hundred and seventeen patients (48 male) with Crohn's disease and 50 (25 male) controls were studied.

RESULTS

There was a significant correlation between hand SFT and BMD (expressed as t scores) at all four measured sites (lumbar spine r = 0.41, P < 0.0001, 95% CI 0.25-0.55, Ward's triangle r = 0.38, P < 0.0001, 95% CI 0.21-0.53, trochanter r = 0.33, P < 0.0001, 95% CI 0.16-0.48, femoral neck r = 0.38, P < 0.0001, 95% CI 0.21-0.53). On stepwise regression analysis, the association remained significant after correcting for age, weight, menstrual status and current steroid use (P < 0.05). Hand SFT was significantly lower in patients with Crohn's disease than controls (difference in means 0.51 mm, 95% CI 0.3-0.72, P < 0.0001). Mean hand SFT was significantly lower in patients with osteoporosis compared to patients with normal BMD (difference in means 0.74 mm, 95% CI 0.33-1.15, P < 0.001), as was that of osteopenic patients compared to patients with normal BMD (difference in means 0.28 mm, 95% CI 0.01-0.55, P < 0.05). In the diagnosis of osteoporosis, the sensitivity of hand SFT ranged from 29% to 93%, with specificities of 54% to 95%.

CONCLUSIONS

Hand SFT is independently associated with BMD in Crohn's disease and is lower than in age-matched healthy subjects. Hand SFT in combination with other easily measurable confounding variables might be useful in screening for osteoporosis in patients with Crohn's disease.