Osteoporosis

Extracted from the WHO Bulletin: International Journal of Public Health

Osteoporosis affects the majority of older persons, including an estimated 33% of post-menopausal women (figure 1). It is called "the silent disease" because by the time symptoms (pain and fractures) appear, the disease is already in an advanced stage. Hip fractures are associated with considerable morbidity, lengthy hospital admissions, and a correspondingly large economic burden (figure 2). Although economic costs associated with osteoporosis are enormously high, the human cost of this disease includes years of debilitating pain, deformity, loss of height, and a diminishing quality of life.¹

Epidemiology

The increase in the global population and prolonged life expectancy with a disproportionate increase in the number of the very elderly means that the burden of osteoporosis is increasing for all societies.² The case is made persuasively that more needs to be done in developed countries, but there is a desperate lack of information about even the basic epidemiology of osteoporosis in many parts of the developing world. For instance, more than half of the total number of fractures worldwide are expected to occur in Asia and Latin America.³ It is also known that the prevalence of osteoporosis varies both from country to country, and within countries.⁴ Differences in race, nutritional status, physical activity, lifestyle and living conditions all contribute to its variability.⁵

Targeting

Health professionals emphasize the need to develop strategies to prevent osteoporotic fractures, however, the varied epidemiological nature of the disease makes targeting difficult. Most of one's bone mass is gained during infancy, childhood and adolescence. One can only expect to build strong bones while the bones are growing. During this period of life many nutritional, physical and other habits are formed and, if they are not appropriate, they may cause failure to attain peak bone mass that may contribute to fractures later in life.⁵ As the young of today throughout the world are now increasingly likely to survive into old age and be increasingly exposed to risk factors, it is arguable that all ages should be targeted to ensure maximal bone strength by the time of most risk, that is in old age.² This means that every effort must be made to ensure that mothers are guaranteed early on, from the moment they become pregnant, the best possible nutrition and hygiene to ensure that their children develop normally and have satisfactory bone mass. It is also necessary to teach a lifelong awareness of health, emphasizing the importance of a balanced diet and the importance of regular physical exercise to avert demineralization and to consolidate bone mass.⁶

Interventions

To date, intervention studies with calcium for up to three years during childhood and adolescence have shown only modest bone gain in Caucasian populations and evidence is lacking that any benefit is maintained in increase peak bone mass.⁷ Many retrospective, cross-sectional and longitudinal observational studies have established a clear association between weight-bearing physical activity and increased bone mass. Some research supports the proposition that early adolescence represents a 'window of opportunity' when the sensitivity of the skeleton to beneficial anabolic effects by mechanical loading is optimal.⁸ Short term controlled studies have also supported this proposition.⁹ These findings are encouraging, but more needs to be done. This should include definition of the nature and amount of exercise that is beneficial, confirmation that benefits to bone health are maintained in the long term, the introduction of effective physical-activity regimens that will encourage retention through adolescence and into adult life, and the rigorous assessment of potential adverse effects so that risk-benefit comparisons can be made.³

A second problem relates to the ability to change lifestyle habits and their impact on risk, and in the context of osteoporosis no studies have addressed these issues. For example, several clinical trials have shown beneficial effects of exercise on bone mass¹⁰ but the effects are small, and the impact on the community has not been tested. It is questionable whether a patient of 40 years of age would maintain an exercise programme until 75 years of age when hip fractures arise. A further problem relates to the impact of remedial factors on the frequency of fractures within a community. Uncertainties remain not only with exercise, but also with nutritional risk factors. Despite the high prevalence of many such factors, the increase in relative risk associated with each is small. For all these reasons, population-based strategies of prevention are not presently feasible. Prevention is therefore more appropriately targeted to those segments of the community at high risk.¹¹

Figure 1 Worldwide lifetime risk for Osteoporotic Fractures

Hormone replacement therapy at menopause is not yet accepted by all women. It is questionable whether this intervention is acceptable worldwide. Women on estrogen or estrogen-progesterone therapy should be tested for osteoporosis prior to ingesting these hormones. The type of test, or how early the test should be performed is presently unknown. Many think, however, an effort should be made to introduce this treatment, particularly because of its usefulness in providing protection against cardiovascular risk factors, whose incidence increases significantly among post-menopausal women.⁶

Prevention

For disease control, socioeconomic factors are inseparable from factors related to the health systems currently in place. Several socioeconomic factors may be considered as barriers to health prevention and are listed as follows:

à A high rate of illiteracy, which in some countries exceeds 50% of the total population and 75% of women;

à Excessive focus of the health system on curative care and insufficient attention to early detection and prevention of diseases;

à Medical training that is frequently too theoretical and ill-adjusted to the needs of the population; physicians are often ill-equipped to deal with these epidemiological situations and to develop sound preventive strategies;

à Inadequate medical information and health education: the dietary advice given by a physician during brief consultation cannot compete with relentless television advertisements for unsuitable products;

à No census of the different diseases and no reliable statistics on the causes of mortality on account of failure to use the standard international death certificate;

à Scant material and human resources to detect and manage diseases at an early stage;

à Inadequate and inefficient health insurance systems that frequently fail to cover screening examinations and preventive treatment such as hormone replacement therapy.⁶

Figure 2 Estimated Hip Fractures

Unhealthy lifestyles are associated with a spectrum of disorders in addition to osteoporosis, and in developing countries, where osteoporosis is considered of less priority, a broad public health message that will have benefits beyond health may achieve greater priority and success. The difficult question is, can public health messages can overcome the pressures of social change in developing countries with diets of poor quality, less exercise, and commercial media promoting foods of poor quality, smoking, and alcohol?²

Conclusions

In developing countries in particular, there are no precise data on the incidence of osteoporosis and its progression; the means of detecting osteoporosis are inadequate; and there is lack of agreement about when to administer a diagnostic test and to whom. Ensuring that people have strong bones throughout their life is no luxury. Indeed, the notion of luxury is not appropriate where health is concerned and it is a question rather of need, and even more so of their right to health. This need must be met as early in life as possible through the development of an integrated strategy suited to each country's epidemiological situation.⁶

References

1.	Delmas PD, Fraser M (1899) Strong bones In later life: luxury or necessity? Bulletin of the World Health Organization The International Journal of Public Health 77(5):416-422.
2.	Woolf AD (1999) Editorial. Strong bones in later life. Bulletin of the World Health Organization The International Journal of Public Health 77 (5):368-369.
3.	Wark JD (1999) Osteoporosis: a global perspective. Bulletin of the World Health Organization The International Journal of Public Health 77 (5):424-426.
4.	Arden N, Cooper C (1998) Present and future of osteoporosis: epidemiology. In: Meunier PJ, ed. Osteoporosis: diagnosis and management. Mosby/Martin Dunitz, London p.1-16.
5.	deCastro JAS (1999) The view from Brazil: desirable but not yet feasible. Bulletin of the World Health Organization The International Journal of Public Health 77(5):426-427.
6.	Khalifa FB (1999) The view from Tunisia: need for an inclusive approach, but not yet feasible. Bulletin of the World Health Organization The International Journal of Public Health 77(5):427-428.
7.	Johnston CG Jr et al. (1992) Calcium supplementation and increases in bone density in children. New England Journal of Medicine 327:82-87.
8.	Khan K et al. (1998) Self-reported ballet classes at age 10 to 12 years are associated with augmented hip bone mineral density in later life. Osteoporosis International 8:165-173.
9.	Morris FL et al. (1997) Prospective 10 month exercise intervention in pre-menarcheal gins: positive effects on bone and lean mass. Journal of Bone and Mineral Research 12:1453-1462.
10.	Berard A, Bravo G, Gautier P (1997) Meta-analysis of the effect of physical activity on the prevention of bone toss in postmenopausal women. Osteoporosis International 7:331-337.
11.	Kanis J (1999) Strategies for osteoporosis treatment Bulletin of the World Health Organization The International Journal of Public Health 77 (5):431-432.

[SCN News is grateful for Permission No. 99.445 granted by the WHO Office of Publications to extract material from the Bulletin of the World Health Organization The International Journal of Public Health 77(5).]