Letha’s Asian Health Secrets

Reading through the following report from JAMA on osteoporosis (excerpt below), a few facts jumped out at me: High risk factors for developing osteoporosis include being a white female over age 50. Me! and that Japanese women tend to have lower Bone Mineral Density (BMD) than Americans but suffer fewer bone fractures.

That may be, in part, genetics, but the bone quality of Japanese women may be better than their American counterparts. That speaks of diet and lifestyle: tofu and other whole soy foods high in healthy phytoestrogens, fish, seaweeds like hijiki, a good source of calcium, and green tea, along with less coffee and cigarettes and more smart exercise. Join Sharon Smith and me this coming Friday Oct. 23rd at NY Open Center to learn how to protect your bones, joints, and ligaments.  

Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture. Bone strength primarily reflects the integration of bone density and bone quality. Bone density is expressed as grams of mineral per area or volume, and in any given individual is determined by peak bone mass and amount of bone loss. Bone quality refers to architecture, turnover, damage accumulation (eg, microfractures), and mineralization. A fracture occurs when a failure-inducing force such as trauma is applied to osteoporotic bone. Thus, osteoporosis is a significant risk factor for fracture, and a distinction between risk factors that affect bone metabolism and risk factors for fracture must be made.

It is important to acknowledge a common misconception that osteoporosis is always the result of bone loss. Bone loss commonly occurs as men and women age; however, an individual who does not reach optimal (ie, peak) bone mass during childhood and adolescence may develop osteoporosis without the occurrence of accelerated bone loss. Hence, suboptimal bone growth in childhood and adolescence is as important as later bone loss in the development of osteoporosis.

Currently there is no accurate measure of overall bone strength. Bone mineral density (BMD) is frequently used as a proxy measure and accounts for approximately 70% of bone strength. The World Health Organization (WHO) operationally defines osteoporosis as bone density 2.5 SDs below the mean for young white adult women. It is not clear how to apply this diagnostic criterion to men and children, or across ethnic groups. Because of the difficulty of accurate measurement and standardization between instruments and sites, controversy exists among experts regarding the continued use of this diagnostic criterion.

Osteoporosis can be further characterized as either primary or secondary. Primary osteoporosis can occur in both sexes at all ages, but often follows menopause in women and occurs later in life in men. In contrast, secondary osteoporosis is a result of medications (eg, glucocorticoids), other conditions (eg, hypogonadism), or diseases (eg, celiac disease).

Osteoporosis has financial, physical, and psychosocial consequences, all of which significantly affect the individual, the family, and the community. An osteoporotic fracture is an outcome of trauma to bone of compromised strength, and its incidence is increased by various other risk factors. Traumatic events can range from normal lifting and bending to high-impact falls. The incidence of fracture is high in persons with osteoporosis and increases with age. The probability that a 50-year-old will have a hip fracture during his or her lifetime is 14% for a white woman and 5% to 6% for a white man. The risk for African Americans is much lower (6% and 3% for 50-year-old women and men, respectively).

Osteoporotic fractures, particularly vertebral fractures, can be associated with chronic disabling pain. Nearly one third of patients with hip fractures are discharged to nursing homes within the year following a fracture. Notably, 1 in 5 patients is no longer living 1 year after sustaining an osteoporotic hip fracture. Hip and vertebral fractures are a problem for women in their late 70s and 80s, wrist fractures are a problem for women in their late 50s to early 70s, and all other fractures (eg, pelvis and rib) are a problem throughout the postmenopausal years. Investigators acknowledge the impact of osteoporosis on other systems (eg, gastrointestinal, respiratory, genitourinary, and craniofacial), but reliable prevalence rates are unknown.

Hip fracture has a profound impact on quality of life, as evidenced by findings that 80% of women older than 75 years preferred death to a bad hip fracture resulting in their placement in a nursing home. However, little data exist on the relationship between fractures and psychological and social well-being. Other quality-of-life issues include adverse effects on physical health (eg, skeletal deformity) and on financial resources. An osteoporotic fracture is associated with increased difficulty with the activities of daily life, as only one third of fracture patients regain their prefracture level of function and one third require placement in a nursing home. Fear, anxiety, and depression are frequently reported in women with established osteoporosis, and such consequences are likely under addressed when considering the overall impact of this condition.

Direct financial expenditures for treatment of osteoporotic fracture in the United States are estimated at $10 billion to $15 billion annually. A majority of these estimated costs are due to inpatient care but do not include the costs of treatment for persons without a history of fractures, nor do they include the indirect costs of lost wages or productivity of either the patient or the caregiver. Consequently, these figures significantly underestimate the true costs of osteoporosis. More needs to be learned about these indirect costs, which are considerable.

How Do Risks Vary Among Different Segments of the Population?

Sex/Ethnicity

The prevalence of osteoporosis and the incidence of fracture vary by sex and race/ethnicity. White postmenopausal women experience almost three quarters of all hip fractures and have the highest age-adjusted incidence of fracture. Most of the information regarding diagnosis and treatment is derived from research on this population. However, women of other ages, races, and ethnicities, as well as men and children, are also affected. Much of the difference in fracture rates among these groups appears to be explained by differences in peak bone mass and rate of bone loss; however, differences in bone geometry, frequency of falls, and prevalence of other risk factors appear to play a role as well.

Both men and women experience an age-related decline in BMD starting in midlife. Women experience more rapid bone loss in the early years following menopause, which places them at earlier risk for fractures. In men, hypogonadism is also an important risk factor. Men and perimenopausal women with osteoporosis more commonly have secondary causes for the bone loss than do postmenopausal women.

African American women have higher BMD than white non-Hispanic women throughout life, and experience lower rates of hip fracture. For reasons not fully understood, some Japanese women have lower peak BMDs than white non-Hispanic women, but have lower rates of hip fracture. Mexican-American women have BMDs between those of white non-Hispanic women and African American women. Limited available information for Native American women suggests they have lower BMDs than white non-Hispanic women.

Risk Factors

Risks associated with low BMD are supported by evidence that includes large prospective studies. Predictors of low bone mass include female sex, increased age, estrogen deficiency, white race, low weight and body mass index (BMI), family history of osteoporosis, smoking, and history of prior fracture. Use of alcohol and caffeine-containing beverages is inconsistently associated with decreased bone mass. In contrast, some measures of physical function and activity have been associated with increased bone mass, including grip strength and current exercise. Levels of exercise in childhood and adolescence have an inconsistent relationship to BMD later in life. Late menarche, early menopause, and low endogenous estrogen levels are also associated with low BMD in several studies.

Although low BMD has been established as an important predictor of future fracture risk, the results of many studies indicate that clinical risk factors related to risk of fall also serve as important predictors of fracture. Fracture risk has been consistently associated with a history of falls, low physical function such as slow gait speed and decreased quadriceps strength, impaired cognition, impaired vision, and the presence of environmental hazards (eg, throw rugs). The risk of a fracture occurring with a fall is increased in tall persons and in falls to the side, and may be influenced by attributes of bone geometry such as hip axis and femur length. Some risks for fracture (eg, advanced age, a low BMI, and low levels of physical activity) probably affect fracture incidence through their effects on bone density, propensity to fall, and inability to absorb impact.

Results of studies of persons with osteoporotic fractures have led to the development of models of risk prediction, which incorporate clinical risk factors along with BMD measurements. Results from the Study of Osteoporotic Fractures, a large longitudinal study of postmenopausal, white, non-Hispanic women, suggest that clinical risk factors can contribute greatly to assessment of fracture risk. In this study, 14 clinical risk factors predictive of fracture were identified. The presence of 5 or more of these factors increased the rate of hip fracture for women in the highest tertile of BMD from 1.1 per 1000 woman-years to 9.9 per 1000 woman-years. Women in the lowest tertile of BMD with no other risk factors had a hip fracture rate of 2.6 per 1000 woman-years, compared with 27.3 per 1000 woman-years among women with 5 or more risk factors. A second model, derived from the Rotterdam study, predicted hip fractures using a smaller number of variables including sex, age, height, weight, use of a walking aid, and current smoking. However, these models have not been validated in a population different from that in which they were derived.

Secondary Osteoporosis

A large number of medical disorders are associated with osteoporosis and increased risk of fracture. These can be organized into several categories: genetic disorders, hypogonadal states, endocrine disorders, gastrointestinal diseases, hematologic disorders, connective tissue diseases, nutritional deficiencies, drugs, and a variety of other common serious chronic systemic disorders such as congestive heart failure, end-stage renal disease, and alcoholism.

The distribution of the most common causes appears to differ by demographic group. Among men, 30% to 60% of osteoporosis cases are associated with secondary causes, the most common of which are hypogonadism, use of glucocorticoids, and alcoholism. In perimenopausal women, more than 50% of cases are associated with secondary causes, the most common of which are hypoestrogenemia, use of glucocorticoids, thyroid hormone excess, and anticonvulsant therapy. In postmenopausal women, the prevalence of secondary conditions is thought to be much lower, but the actual proportion is not known. In 1 study, hypercalciuria, hyperparathyroidism, and malabsorption were identified in a group of white postmenopausal women with osteoporosis who had no history of conditions that cause bone loss. These data suggest that additional testing of such women may be indicated, but an appropriate or cost-effective evaluation strategy has not been determined.

Glucocorticoid use causes the most common form of drug-related osteoporosis, and the long-term administration of glucocorticoids for disorders such as rheumatoid arthritis and chronic obstructive pulmonary disease is associated with a high rate of fracture. For example, in 1 study, a group of patients treated with 10 mg/d of prednisone for 20 weeks experienced an 8% loss of BMD in the spine. Some experts suggest that any patient who receives prednisone or other orally administered glucocorticoids in a dose of 5 mg/d or more for longer than 2 months is at high risk for excessive bone loss.

People who have undergone organ transplantation are at high risk for osteoporosis due to a variety of factors, including pretransplant organ failure and use of glucocorticoids after transplantation.

Hyperthyroidism is a well-described risk factor for osteoporosis. In addition, some studies have suggested that women receiving thyroid replacement therapy may also be at increased risk for excessive bone loss, suggesting that careful regulation of thyroid replacement is important.

Residents of Long-term Care Facilities

Residents of nursing homes and other long-term care facilities are at particularly high risk of fracture. Most have low BMD and a high prevalence of other risk factors for fracture, including advanced age, poor physical function, low muscle strength, poor nutrition, decreased cognition and high rates of dementia, and, often, use of multiple medications.