Osteoporosis: Epidemiology, Diagnosis, and Treatment

Mohammad Masud Iqbal, MD, MPH, MSPH, Department of Epidemiology and International Health, School of Public Health, University of Alabama at Birmingham.

South Med J. 2000;93(1) 

In This Article

Epidemiology

As the average age of the world's population shifts upward, the incidence and prevalence of osteoporosis and its economic burden on society will increase further. Surveys based on data from developed countries show that the number of individuals aged 45 years and older increased from about 155 million in 1960 to 206 million in 1980. This number can be expected to rise to 257 million by the year 2000.[1] This trend is true not only for industrialized countries, but also in the developing countries. The world population of women older than 45 is therefore set to more than double in this time. More than 200 million women worldwide have osteoporosis. Estimates indicate that the number of osteoporotic hip fractures occurring in the world each year will rise from 1.66 million to 6.26 million by the year 2050, thereby implying an urgent need for preventive strategies.[2]

In the United States, osteoporosis is a major public health threat for 24 million Americans,[3] 80% of whom are women. Ten million individuals already have osteoporosis, and 14 million more have low bone mass, placing them at increased risk for this disease. Osteoporosis is responsible for more than 1.5 million fractures annually, among them more than half a million vertebral fractures, 300,000 hip fractures, 200,000 wrist fractures, and 300,000 fractures of other sites. Approximately 37,500 people die each year after complications related to osteoporotic fracture. Osteoporosis also caused more than 44 million patient-days in nursing homes and an estimated $13.8 billion in annual health care expenditures in 1995.[4,5] The direct medical costs associated with hip fractures among men and women have been estimated to be between $5.4 billion and $7.4 billion.[4] Costs will escalate as the proportion of elderly in the population increases; costs of hip fractures are projected to reach $62 billion in the United States by the year 2020.[4] According to one projection, demographic changes alone could lead to an increase in the number of hip fractures annually to 840,000 by the year 2040.[4]

In the United States, roughly 1 in 4 women more than age 50 has osteoporosis. The overall prevalence of osteoporotic fractures rises dramatically in menopausal women. Bone loss is more abrupt for the first decade after the onset of menopause, followed by more gradual loss thereafter.[6] With increasing age, fracture incidence increases. The frequency of hip fractures increases exponentially with age, particularly after age 70, and is more commonly seen in white women.

About 32% of women who live to age 80 have hip fractures.[7,8] A woman's risk of a hip fracture equals the combined risk of breast, uterine, and ovarian cancer, and the risk of dying of hip fracture is equal to breast cancer mortality.[9] The prevalence of vertebral fractures is 42% in women of advanced age and/or who have decreased bone mass.[8] In women, a rapid rise of vertebral fractures, which is initially associated with the onset of menopause, is followed by an increase in the frequency of wrist and hip fractures due to age-related bone loss.

Osteoporosis develops less often in men than women because bone loss starts later and progresses more slowly in men, and there is no period of rapid hormonal change and accompanying rapid bone loss. Differences in bone geometry and remodeling also contribute to the lower rate of fractures in men.[10] However, in the past few years, the problem of osteoporosis in men has become recognized as an important public health issue, particularly in light of estimates that the number of men older than 70 will double between 1993 and 2050 according to the US National Osteoporosis Foundation.

Roughly 1 in 8 men more than 50 years old has osteoporosis. Presently, more than 2 million men in the United States are affected by osteoporosis, and another 3 million are at risk for this disease. Each year, men have one third of all hip fractures that occur, and one third of these men will not survive more than a year. The frequency of hip fracture increases exponentially with age, particularly after age 70, and 17% of men who live to age 80 have hip fractures.[7,8] In addition to hip fracture, men also have painful and debilitating fractures of the spine, wrist, and other bones due to osteoporosis.

In the elderly, use of psychotropic agents, the high rate of orthostatic hypotension (frequently due to antihypertensive drug therapy), and the wide use of polypharmacy contribute to the increasing incidence of falls and consequent fractures. In 90% of hip fractures with falling involved, only 5% or less of these falls resulted in subsequent fractures.[11]

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