The National Institutes of Health (NIH) has released a consensus statement on the prevention, diagnosis, and therapy of osteoporosis. The statement was prepared by a nonfederal, nonadvocate panel of experts in the field and is an independent panel report, not an official document of the NIH or the federal government. The conference, the Consensus Development Conference on Osteoporosis Prevention, Diagnosis, and Therapy, was sponsored by the NIH in March 2000. The complete text of the consensus statement can be found on the internet atwww.consensus.nih.gov.

Osteoporosis is a disorder of the skeletal system characterized by weakened bone strength, which results in an increased risk of fracture. In the United States, approximately 10 million people are estimated to have osteoporosis, and another 18 million are at increased risk as a result of low bone mass. Although osteoporosis was once thought to be a disorder that struck primarily elderly women, it is no longer considered to be a natural part of aging or dependent on age or sex. Research efforts have resulted in great progress in understanding the causes, diagnosis, and treatment of osteoporosis. It is now understood that optimizing the bone health of men and women early in life is crucial in preventing osteoporosis later in life.

The NIH consensus panel addressed the following questions: What is osteoporosis and what are its consequences? How do risks vary among different segments of the population? What factors are involved in building and maintaining skeletal health throughout life? What is the optimal evaluation and treatment of osteoporosis and fractures?

The panel also identified several areas for future research, including maximizing peak bone mass in girls and boys, assessing patients for risk factors, linking osteoporosis and its impact to quality of life, and treating neuro-psychiatric disorders, such as depression and anorexia nervosa, that are associated with osteoporosis later.

Diagnosing and Preventing Osteoporosis

Patients with osteoporosis have decreased bone strength, lack of bone density and bone quality, and are more prone to fractures. Although osteoporosis is linked with bone loss, which often occurs as people age, people who fail to develop adequate bone density while they are young may develop osteoporosis without experiencing bone loss. Suboptimal bone growth in childhood and adolescence is as important as bone loss to the development of osteoporosis. Because osteoporosis is associated with elderly women, it often goes unrecognized in other populations.

The costs of osteoporosis are financial, physical, and psychosocial. Direct financial expenditures for treatment of osteoporotic fracture are estimated at $10 to $15 billion annually. A fracture can be the result of a traumatic event, such as falling, or it can be the result of normal, everyday activities. Osteoporotic fractures, particularly vertebral fractures, can be associated with chronic and disabling pain. Almost one third of patients with hip fractures are placed in nursing homes within one year after a fracture. One in five of such patients is no longer living one year later.

Osteoporosis integrates two main features: bone density (usually expressed as grams of mineral per area or volume) and bone quality (architecture, damage accumulation, and mineralization of the bone). There is no consensus or standardized way to measure overall bone strength, although for young white adult women, the World Health Organization defines osteoporosis as bone density 2.5 standard deviations below the mean. Osteoporosis may be primary or secondary. Primary osteoporosis occurs mainly in post-menopausal women and in older men. Secondary osteoporosis is a result of medications, other conditions, or diseases (e.g., glucocorticoid-induced osteoporosis, hypogonadism, and celiac disease).

Although residents of nursing homes and other long-term care facilities are at particularly high risk of osteoporosis-related fracture, men and women experience an age-related decline in bone mineral density (BMD) starting in midlife. Women experience more rapid bone loss in the early years after menopause, which places them at earlier risk for fractures. An important risk factor in men is hypogonadism. Men and perimenopausal women with osteoporosis more commonly experience secondary osteoporosis than do postmenopausal women.

Predictors of low bone mass include female sex, increased age, estrogen deficiency, white race, low weight and body mass index, family history of osteoporosis, smoking, and history of fracture. Late menarche, early menopause, and low endogenous estrogen levels are also associated with low BMD.

A number of risk factors or medical conditions may result in secondary osteoporosis. Among men, 30 to 60 percent of osteoporosis cases are associated with secondary causes; hypogonadism, use of glucocorticoids, and alcoholism are the most common. In perimenopausal women, more than 50 percent of cases are associated with secondary causes, with the most common causes being hypoestrogenemia, glucocorticoids, thyroid hormone excess, and anticonvulsant therapy. Glucocorticoid use is the most common form of drug-related osteoporosis. Hyperthyroidism is a well-described risk factor for osteoporosis. More attention should be focused on skeletal health in people with conditions known to be associated with secondary osteoporosis.

The bone mass attained early in life is perhaps the most important determinant of lifelong skeletal health. Individuals with the highest peak bone mass after adolescence have the greatest protective advantage. Nutrition, exercise, gonadal steroids, and growth hormone and body composition all play a role in bone density. Building good eating habits early in life is important. In particular, getting enough calcium and vitamin D is crucial. Exercise, particularly resistance-based and high-impact exercise, is also beneficial because it helps increase bone density. In addition, sex steroids (estrogen, testosterone, growth hormone, and insulin-like growth factor I) secreted during puberty substantially increase BMD and peak bone mass.

Evaluation and Therapy for Osteoporosis

A history and physical examination are essential in evaluating fracture risks and should include assessment for loss of height and change in posture. Laboratory evaluation for secondary causes of osteoporosis should be considered when osteoporosis is diagnosed. The most commonly used measurement to diagnose osteoporosis and predict fracture risk is based on assessment of BMD, which is determined largely by mineral content. BMD measurement should be considered in patients at high risk for secondary osteoporosis. However, the value of universal screening has not been established; an individualized approach is recommended instead.

Fracture prevention is the primary goal in the treatment of patients with osteoporosis. Strategies for prevention include therapies that enhance bone mass, such as engaging in weight-bearing exercise, and reduce risk or consequences of falls. The effects of exercise beyond those directly on bone, such as improved muscular strength and balance, may be significant in fracture-risk reduction. Hormone replacement therapy is an established approach for osteoporosis treatment and prevention; and early surgical management of hip fractures is associated with improved outcomes and decreased perioperative morbidity.

Conclusions

The NIH consensus statement concludes with the following:

• Osteoporosis occurs in all populations at all ages.

• Adequate calcium and vitamin D intake are crucial to develop optimal peak bone mass and to preserve bone mass throughout life.

• Gonadal steroids are important determinants of peak and lifetime bone mass in men, women, and children.

• Regular exercise contributes to development of high peak bone mass and may reduce the risk of falls in older individuals.

• Assessment of bone mass, identification of fracture risk, and determination of who should be treated are the optimal goals when evaluating patients for osteoporosis.