Differences in clinical characteristics in patients with extremes of discordance in bone mineral density in the hips

Background/Aims Osteoporosis is a clinical condition which is characterised by low bone mineral density (BMD) and is associated with increased risk of fractures and subsequent increased morbidity and mortality. Usually BMD is measured at either the spine or the non-dominant hip (usually the left hip). However, our DEXA scanner routinely measures BMD at both hips and enables discordance in terms of BMD to be measured. This study aimed to ascertain whether patients with extremes of discordance in their BMD between both hips are more likely to have certain clinical characteristics and different risk for fractures. Methods Data from a dual-energy X-ray absorptiometry (DEXA) scanner in the North West of England were used. Patients who were referred between 2004-2011 were studied. Patients had both hips scanned as well as risk factors and presence of fracture recorded. Those that had a BMD T-score difference from 0 and upwards formed the positive discordance group. Those that had a BMD T-score difference of either less than or equal to -1SD formed the negative discordance group. These two groups were compared using independent sample t-tests for continuous variables and chi-squared tests for categorical variables. Logistic models were then fitted to look at the odds of fracture in each group. Results The hip BMD T-scores of 10,335 patients were measured. Mean age was 62.41 (12.99) with 82.61% being female. The odds ratio for the measured risk factors and the association with fracture are shown in Table 1 below. Significant risk factors are highlighted Conclusion Patients that had a positive discordance had lower weight and BMI. Also, there was a higher proportion of females in the positive discordance group. These are important risk factors used in fracture risk assessment. It is possible that if BMD is only measured in one hip, patients may be misclassified as not having osteoporosis. However, if BMD is measured in both hips, discordance might be present suggesting osteoporosis in the right hip. This discordance in BMD in our study is associated with some risk factors like age and sex which may increase future fracture risk. Disclosure A. Saeed: None. M. Bukhari: None.