Comparison of T- and Z-score in identifying risk factors of osteoporosis in inflammatory bowel disease patients.

OBJECTIVE Most studies have shown contradictory results regarding predictive factors of osteoporosis in inflammatory bowel disease (IBD). Since in these studies either T- or Z-scores has been used, our aim was to compare T- and Z-score in identifying risk factors of osteoporosis in IBD patients. MATERIALS AND METHODS Bone density was measured by dual X-ray absorptiometry (DXA) at L2-L4 of the spine and femoral neck in 122 patients. Twenty-two clinical parameters were recorded prior to DXA and evaluated by univariate and multivariate analysis. RESULTS On multivariate analysis, cumulative steroid dose was a predictive factor of femoral neck T-score (p<0.001) and Z-score (p=0.001). Age was a predictive factor of femoral neck T-score (p<0.001). BMI was a predictive factor of femoral neck Z-score (p=0.03). None of the other 19 variables tested had any predictive value for bone density. Age >or=55 years was a risk factor of low femoral neck T-score (OR 5.08, 95% CI 1.90-13.57, p=0.001), as was cumulative dose of prednisolone >or=5 g (OR 3.41, 95% CI 1.50-7.73, p=0.004). CONCLUSIONS There is a discordance of results depending on whether T- or Z-scores are used in analysis. Among 22 parameters, cumulative steroid dose and age proved to be the most important factors.