Chen Yu-ming. / "January 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 177-197). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Objectives. beta-blockers can alter bone turnover and increase bone formation in animals. It is unknown whether beta-blockers have similar bone protective effects in humans. We aimed to estimate the effects of beta-blockers on bone mineral density (BMD) and fractures using data from the Canadian Multicentre Osteoporosis Study, a large prospective cohort study. / Methods. All medications, including beta-blockers, taken at baseline and after five years of follow-up were recorded. BMD was measured at baseline. During the five years of follow-up, incident minimal trauma fractures were documented by yearly questionnaires. To compare users of beta-blockers to non-users while controlling for possible confounders, multiple linear regression was utilized to estimate between group differences in BMD and multivariate logistic regression was employed to estimate differences in fracture risk. / Results. Of the 9423 participants, 236 of 2884 males (8.2%) and 600 of 6539 females (9.2%) used beta-blockers at some point during the study. In men, beta-blocker users had differences of +1.1% (95% confidence interval [CI] -0.9%, 3.0%) and +1.2% (95% CI -0.5%, 4.0%) in baseline BMD at the total hip and at the lumbar spine, respectively, compared to non-users. In women, beta-blocker users had differences of +0.05% (95% CI -1.2%, 1.3%) and +0.2% (95% CI -1.3%, 1.7%) for the BMD of the total hip and the lumbar spine, respectively, compared to non-users. For users of beta-blockers at baseline, the adjusted odds ratio (OR) for any minimal trauma fracture was 1.23 (95% CI 0.67--2.25) in men and 1.02 (95% CI 0.76--1.35) in women. Chronic use (user at baseline and year 5) in men had an OR for any minimal trauma fracture of 2.1 (95% CI 1.0--4.3). In women who used beta-blockers at baseline but not at year 5, the OR for hip fracture was 6.3 (95% CI 2.0--19.3). The risk of fractures for other sites was inconclusive owing to wide confidence intervals. / Conclusion. Despite relatively large numbers of subjects, wide confidence intervals do not permit strong conclusions with regards to the effect of beta-blockers on BMD in men. Using a 2% limit of clinical importance for BMD, there appears to be no effect of beta-blockers on BMD in women. There is some evidence from our study that beta-blockers may be associated with an increased risk of fractures in certain subsets of users.

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