Osteoporosis is a major public health threat that affects more than half of persons older than 50 years. The most common bone disease in humans, osteoporosis is associated with pain, disability, and increased risk of mortality.
The primary reference that clinicians use in managing osteoporosis is the National Osteoporosis Foundation’s (NOF) Clinician’s Guide to Prevention and Treatment of Osteoporosis, published in 1999 and updated in 2003. The guidelines in this publication represented the standard of care but did not adequately address some populations that may be affected by osteoporosis. For example, little guidance was offered on how to treat men with osteoporosis or how to approach the variations associated with ethnicity.
Many clinicians welcomed the comprehensive revised NOF guidelines released in February 2008, appreciating the new practice parameters that addressed previous areas of concern not mentioned in the 2003 document. The NOF guidelines were complemented by release of the World Health Organization’s (WHO) fracture risk assessment tool (FRAX), which helped physicians and patients gain a better understanding of a specific patient’s 10-year absolute risk of an osteoporosis-related fragility fracture. The primary goal of treatment is to reduce the incidence and the morbidity and mortality associated with osteoporosis-related fragility fractures. Treatment often includes lifestyle modifications, such as performance of weight-bearing exercises. A number of pharmacological therapies are currently available, although gaining patients’ adherence to therapy remains a challenge. Several new agents are under investigation.
This 2-part article provides an overview of osteoporosis diagnosis and management. In this first part, we interpret and summarize recent publications in this field; pool the data that are of greatest relevance to primary care physicians, including the epidemiology; review technologies available for diagnosis; and help decipher whom to test and to treat. The second part, to appear in a later issue of this journal, will discuss the current therapies for osteoporosis, their adverse effects, and reasonable approaches to monitoring.
Osteoporosis is a threat to an estimated 44 million Americans. Ten million Americans are thought to already have the disorder and an estimated 34 million more to have low bone mass.1
Significant risk has been reported in all ethnicities. An estimated 20% of white and Asian women older than 50 years are thought to have osteoporosis; in a similar age-group, 5% of African American women and 10% of Hispanic women are thought to have the disease.
Osteoporosis risk is increasing most rapidly among Hispanic women.1 Some studies have shown that they consume less calcium than the recommended dietary allowance in all age-groups. Also, Hispanic women are twice as likely as white women to have diabetes mellitus, which may increase their risk of osteoporosis.2 Although osteoporosis is largely thought of as a disease that affects women, its prevalence is 7% in white men, 5% in African American men, and 3% in Hispanic men.3
Research into the diagnosis and management of osteoporosis continues to expand; the disease is projected to affect an even larger portion of the US population over the next 15 years as the average age increases. The economic burden is estimated to rise to more than $17 billion annually in the United States alone.4 By 2025, the costs of osteoporotic-related fractures are expected to rise to about $25 billion.1 The economic consequence is proposed to increase by about 50%.
A dramatic reality is that 1 of 2 women and 1 of 4 men 50 years and older probably will have an osteoporosis-related fracture in their lifetime. Therefore, clinicians should be well aware of osteoporosis and have a good understanding of its diagnosis and appropriate management.
The NOF defines osteoporosis as a disease characterized by low bone mass and structural deterioration of bone tissue that lead to bone fragility and an increased susceptibility to fractures (especially of the hip, spine, and wrist, although any bone can be affected).1 The WHO defines osteoporosis as a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fractures.5
The WHO further defines osteoporosis through radiographic parameters obtained from dual-energy x-ray absorptiometry (DXA) on the basis of its 1994 classification (Table 1).5 T-score refers to the standard deviation between a patient’s bone mineral density (BMD) and that of a young adult in the reference population. The Z-score is a comparison of the patient’s BMD with an age-matched population.5
Osteopenia is now generally accepted as being synonymous with low bone mass. Note that patients with low bone mass are not necessarily at high risk for fracture.6
A diagnosis of osteoporosis may be made clinically by the occurrence of fragility fractures. In their absence, however, the gold standard test for low BMD and osteoporosis is DXA. A fragility fracture is defined as a pathological fracture that occurs as a result of a fall from a standing height or lower. Fractures in this context suggest weakness of the bony skeleton.
However, bone strength reflects not only BMD—the amount of calcium hydroxyapatite per square centimeter of bone—but also integration of bone density with bone quality (the architecture, turnover, damage accumulation [eg, microfractures], and mineralization of bone).7 Despite widespread use of DXA for measurement of BMD, currently there is no simplistic way to measure bone quality that also can affect overall bone strength.
Clinical experience has highlighted a number of risk factors related to the development of osteoporosis and fragility fractures (Table 2). Some are modifiable, but others, such as genetic and ethnic predisposition, are beyond the control of the patient and clinician.
Fluctuating hormone levels in both men and women are known risk factors. Low estrogen levels in women (menopause and amenorrhea) and low levels of testosterone in men are both implicated. There is an increased risk with older age, a history of previous fracture, and a family history of osteoporosis or family history of previous fracture. Other reported variables that influence osteoporosis development include low body mass index; inactivity; cigarette smoking; excessive alcohol(Drug information on alcohol) intake (defined as 3 or more drinks per day); and a diet low in calcium and vitamin D but high in protein, sodium, and caffeine(Drug information on caffeine).
The use of a number of medications has been associated with an increased risk of osteoporosis. Systemic corticosteroids, heparin(Drug information on heparin), levothyroxine replacement therapy, and anticonvulsant therapy are among the most common.1 Diseases that may result in an increased risk of secondary osteoporosis include endocrinopathies, malabsorptive GI conditions, congestive heart failure, blood dyscrasia, osteogenesis imperfecta, amyloidosis, and inflammatory arthropathies.1 Read The Full Report