PubMed · 1346873
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J Studd. 1992-02-22. Dependence and oestrogen replacement.. https://pubmed.ncbi.nlm.nih.gov/1346873/
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BACKGROUND: In a great many of observational studies, whether there is a relevance of resistin levels on bone mineral density (BMD) and fracture occurrence has been inconsistently reported, and the causality is unclear. METHODS: We aim to assess the resistin levels on BMD and fracture occurrence within a Mendelian randomization (MR) analysis. Exposure and outcome data were derived from the Integrative Epidemiology Unit (IEU) Open genome wide association studies (GWAS) database. Screening of instrumental variables (IVs) was performed subject to conditions of relevance, exclusivity, and independence. Inverse variance weighting (IVW) was our primary method for MR analysis based on harmonized data. Weighted median and MR-Egger were chosen to evaluate the robustness of the results of IVW. Simultaneously, heterogeneity and horizontal pleiotropy were also assessed and the direction of potential causality was detected by MR Steiger. Multivariable MR (MVMR) analysis was used to identify whether confounding factors affected the reliability of the results. RESULTS: After Bonferroni correction, the results showed a suggestively positive causality between resistin levels and total body BMD (TB-BMD) in European populations over the age of 60 [β(95%CI): 0.093(0.021, 0.165), P = 0.011]. The weighted median [β(95%CI): 0.111(0.067, 0.213), P = 0.035] and MR-Egger [β(95%CI): 0.162(0.025, 0.2983), P = 0.040] results demonstrate the robustness of the IVW results. No presence of pleiotropy or heterogeneity was detected between them. MR Steiger supports the causal inference result and MVMR suggests its direct effect. CONCLUSIONS: In European population older than 60 years, genetically predicted higher levels of resistin were associated with higher TB-BMD. A significant causality between resistin levels on BMD at different sites, fracture in certain parts of the body, and BMD in four different age groups between 0-60 years of age was not found in our study.
BACKGROUND: HMG Co-A reductase inhibitors (statin lipid-lowering drugs) have been associated with a reduced rate of fractures in some studies, but not in others. We examined the relationship between statin use and bone density among postmenopausal women. METHODS: We conducted a cross-sectional survey at one academic medical center. Postmenopausal women who underwent bone densitometry and agreed to a telephone interview were surveyed about osteoporosis risk factors, use of hormone replacement therapy and osteoporosis medications and statin exposure. We then developed linear regression models adjusting for known counfounders to assess the relationship between statin use and bone mineral density (BMD). RESULTS: Of 339 women studied, 162 were current or past users of statins, and 177 were not. Statin users and non-users were similar with respect to age, race, prior fracture history, the presence of medical conditions associated with osteoporosis, use of medications for osteoporosis, use of tobacco and use of oral glucocorticoids. Statin users had significantly higher body mass index (BMI) and rates of thiazide use, and were more likely to abstain from alcohol. After adjusting for important confounders, we found that statin use was associated with a significantly higher t-score at the total hip (-0.53 +/- 0.17) compared with non-users (-0.83 +/- 0.18; p = 0.02). At the lumbar spine, there was a trend toward higher t-scores in statin users (-0.91 +/- 0.24) compared with non-users (-1.21 +/- 0.23; p = 0.08). CONCLUSIONS: These results support the hypothesis that statin use is associated with higher BMD. While it is unclear whether their relationship is causal, further controlled studies examining bone formation and resorption would help determine the clinical implications of these findings.
OBJECTIVE: To evaluate the reproducibility of imaging and analysis for bone mineral density (BMD) determination using digital computer-assisted X-ray radiogrammetry (DXR; Pronosco X-posure, version V.2, Sectra Pronosco, Denmark); to verify potential factors that influence BMD extrapolation such as tube voltage, film-focus distance (FFD), film quality and brand (Kodak T-MAT-Plus, Konika SRH, Agfa Scopix), imaging technology (conventional, digital), imaging system (Kodak, Agfa) and exposure level (mAs); and to clarify whether DXR analysis based on printouts of digital images is comparable to analysis of conventional images. DESIGN AND PATIENTS: The hand of a cadaver was X-rayed using varied parameters: 4-8 mAs, 40-52 kV, 90-130 cm FFD. Radiographs under standardised conditions were performed 10 times using a conventional machine (Philips Super 80 CP) and the printouts of a digital system (Digital Diagnost Philips Optimus) for the analysis of reproducibility. One image was scanned and analysed 10 times additionally for imaging reproducibility. RESULTS: Reliability error of the system for the imaging process using conventional radiographs-rays was 0.49% (standard conditions: 6 mAs, 40 kV, 1 m FFD), using printouts of digital images was 2.89% (4 mAs, 42 kV, 1 m FFD) and regarding the analysis process was 0.22%. BMD calculation is not affected by alterations in FFD (precision error 1.21%), mAs (0.83%) or film quality/brand (0.38%), but differs significantly depending on tube voltage (2.70%). The system was not able to analyse conventional images with tube voltages of 49/52 kV. CONCLUSION: DXR technology is stable with most of the tested parameters. Normative data should exclusively be used for calculations using similar tube voltage or correction factors. All other parameters had no significant influence on the BMD calculation. Reproducibility is high. For technical reasons it is not recommended to use the printouts of digital images for BMD determination.