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Epidemiology Study










The Osteoporotic Fractures in Men Study (MrOS) was initially designed to determine the risk factors for fractures and osteoporosis in men age 65 and older. The scope of the project expanded over time, to broadly include healthy aging, comprising extensive assessments about musculoskeletal aging (e.g. physical performance, falls, osteoarthritis, and sarcopenia). Additional information was collected about sleep, cardiovascular outcomes (in a subset), incident prostate cancer and lower urinary tract symptoms. The study was funded by the following components of the National Institutes of Health (NIH): the National Institute of Aging (NIA); the National Institute of Arthritis, Musculoskeletal, and Skin Disease (NIAMS); National Heart, Lung and Blood Institute (NHLBI) and the National Cancer Institute (NCI).


Osteoporosis has often been associated with older women, but men also face an increased risk of bone loss as they age. However, prior to MrOS, there was a lack of information concerning osteoporosis in older men. The deficit of information made it difficult to develop methods to diagnose, assess, and prevent male osteoporosis. MrOS was established to identify the risk factors associated with osteoporosis and bone fracture in older men.

Study Design

MrOS, a multi-center longitudinal, observational study, was established in 1998. The U.S. clinical sites were located at the University of Alabama at Birmingham; Oregon Health and Science University; Stanford University; University of Minnesota; University of Pittsburgh; and University of California, San Diego. Each site was expected to enroll at least 950 men and the enrollments were required to reflect the race and age demographics of the site’s geographic area. In total, 5,994 U.S. participants were enrolled in MrOS between March 2000 and April 2002. In 2001, the study expanded internationally to collaborate with sites in Hong Kong and Sweden. The Hong Kong site enrolled 2,000 men and the sites in Sweden enrolled approximately 3,000 men.

MrOS U.S. study participants had to be men aged 65 and older; ambulatory; live near the clinical site during the study period; able to adhere to study procedures; and had not had bilateral hip replacement or another condition that would prevent or interfere with study participation. After enrollment, participants were required to complete a baseline examination, which included the evaluation of bone mineral density and structure, physical function, quality of life, diet, and medical history. During the follow-up period, questionnaires were used to capture information about the occurrence of back pain, falls, fractures, newly diagnosed prostate cancer and recent prostate biopsies. Participants completed the regular questionnaires every four months and a more extensive questionnaire periodically. At approximately 5-year intervals, participants underwent a comprehensive assessment at the clinic site. Most baseline evaluations were repeated during the comprehensive assessments. Follow-up clinical assessments included detailed measures of sleep health (including overnight polysomnography in ~3000 men), osteoarthritis, and expanded assessment of physical function and performance.

Interventions/Treatment Groups

No interventions or treatment groups were used for this study.


Participants underwent clinic evaluations, in addition to interviewer-administered and self-administered questionnaires at regular intervals during the study period. Information about incident fractures was collected through the questionnaires and verified via medical records obtained from the participant’s primary healthcare provider. The incidences of falls, back pain, prostate cancer, prostate biopsies were also evaluated. Incident cardiovascular events over several years were adjudicated in a subset of participants.


MrOS has provided much insight into healthy aging in older men, which has led to hundreds of research publications based on MrOS data. Study findings have shown that bone loss in men accelerates with age and low bone density, especially when accompanied by other risk factors, is correlated to an increased incidence of bone fracture in older men. A variety of additional risk factors for falls, fracture and physical disability have also been identified.