Reliability Estimates and Changes in Total Bone Mineral Density in Adults

Abstract

2057 Osteoporosis and low bone mineral density are serious health issues affecting 44 million people in the United States. Considered a disease of aging, osteoporosis is responsible for over 250,000 hip fractures per year. Proper measurement of bone mineral density is crucial in the diagnosis and treatment of osteoporosis. Dual Energy X-ray Absorptiometry (DEXA) is considered the Gold Standard for the measurement of Total Bone Mineral Density (TBMD); however, few researchers have evaluated the reliability of DEXA to measure TBMD. PURPOSE: To determine the reliability of TBMD measures from DEXA and whether there was a significant difference in pre-post TBMD measures over a 12 week period. METHODS: The participants (N = 22) participants were (mean ± sd) 30.9 ± 13.5 yrs of age had their TBMD measured twice over a 12 week duration with the same DEXA. The sample included 8 males and 14 females. TBMD was determined by DEXA. The DEXA was calibrated prior to each test utilizing standardized procedures. Repeated Measures Analysis of Variance (ANOVA) was utilized to determine the reliability estimates and whether there was a significant change in TBMD measures. RESULTS: Descriptive statistics (mean ± sd) of TBMD for the pre and post-test measures were 1.288 ± 0.099 g/cm2 and 1.259 ± 0.103 g/cm2, respectively. Repeated Measures ANOVA revealed a high reliability for both measures (R = .973). Reliability estimates for a single treatment were also high (R = .947). There was a statistically significant (F(1,21) = 76.8, p = .0001) decrease in TBMD over the 12 week duration of the study. CONCLUSIONS: This data reveals that further investigation is warranted to evaluate the reliability of measures of total body mass density from the DEXA. An important finding in this study is the systematic decrease in TBMD. Most researchers report no significant changes in TBMD over short periods of time (less than 6 months). Considering the size of the sample, finding a significant and systematic decrease in TBMD demonstrates the need for studies with larger sample sizes.