Osteoporosis is a disease affecting many millions of people around the world. It is characterized by low bone mass and micro-architectural deterioration of bone tissue, leading to bone fragility and a consequent increase in risk of fracture.
The incidence of vertebral and hip fractures increases exponentially with advancing age (while that of wrist fractures levels off after the age of 60 years). Osteoporosis fractures are a major cause of morbidity and disability in older people and, in the case of hip fractures, can lead to premature death. Such fractures impose a considerable economic burden on health services worldwide.
Worldwide variation in the incidence and prevalence of osteoporosis is difficult to determine because of problems with definition and diagnosis. The most useful way of comparing osteoporosis prevalence between populations is to use fracture rates in older people. However, because osteoporosis is usually not life-threatening, quantitative data from developing countries are scarce. Despite this, the current consensus is that approximately 1.66 million hip fractures occur each year worldwide, that the incidence is set to increase four-fold by 2050 because of the increasing numbers of older people, and that the age-adjusted incidence rates are many times higher in affluent developed countries than in sub-Saharan Africa and Asia.
In countries with a high fracture incidence, rates are greater among women (by three- to four-fold). Thus, although widely regarded in these countries as a disease that affects women, 20% of symptomatic spine fractures and 30% of hip fractures occur in men. In countries where fracture rates are low, men and women are more equally affected. The incidence of vertebral and hip fractures in both sexes increases exponentially with age. Hip-fracture rates are highest in Caucasian women living in temperate climates, are somewhat lower in women from Mediterranean and Asian countries, and are lowest in women in Africa. Countries in economic transition, such as Hong Kong Special Administrative Region (SAR) of China, have seen significant increases in age-adjusted fracture rates in recent decades, while the rates in industrialized countries appear to have reached a plateau.
A Worldwide Problem and the Implications in Asia
Osteoporosis is a condition characterised by low bone mineral density, microarchitectural deterioration of bony tissue, and a consequent increase in fracture risk. With rapid ageing of the Asian population, osteoporosis has become one of the most prevalent and costly health problems. The public health impact of osteoporosis stems from its association with fractures of the hip, spine and forearm. Between 10% and 20% of patients sustaining a hip fracture die within a year of the event, and among those who survive, almost two-thirds remain disabled. The medical costs of osteoporosis and its attendant fractures have been placed at $5.2 billion each year in the US and £615 million each year in the UK. The cost of treating hip fractures in Hong Kong exceeds 1% of the total hospital budget. It has been projected that this cost will rise exponentially as the population ages.
In the 1960s, there were pronounced geographical variations in hip fracture incidence, with rates being much higher in Caucasians living in Northern Europe and North America than in Asian and Negroid populations. In the 1960s, the age-adjusted incidence of hip fracture in Hong Kong Chinese was approximately 13% to 30% of that observed in Caucasians. However, with socio-economic development in many Asian countries, the incidence of hip fractures has risen considerably. For instance, the incidence of hip fractures in Hong Kong Chinese increased by more than 2-fold in the last 2 decades. In Singapore, the incidence of hip fracture increased from 7 per 10,000 in women who were 60 years of age and older in 1957 7 to 15 per 10,000 in 1985.
The results of the Asian Osteoporosis Study, which is the first multi-centre epidemiological study conducted in Asia, confirmed that the hip fracture incidence rates in Hong Kong and Singapore were approaching those observed in American Caucasians. Although the rates in Malaysia and
Thailand were much lower, these are likely to increase with urbanisation and ageing.
According to projections by the World Health Organization, there will be a total of 900 million men and women who are 65 years of age and older in Asia by the year 2050. As a result, while only 30% of all hip fractures in the world occurred in Asia in 1990, more than 50% of all hip fractures will occur in this continent by the year 2050. By then, the total number of subjects with hip fracture in Asia will be approximately 3.2 million per year. There is no doubt that primary preventive strategies for osteoporosis should be implemented in Asia. However, more challenging issues include rationing of bone mineral density measurements and finding the money to treat osteoporosis.
The results of the Asian Osteoporosis Study suggested that many lifestyle factors might be associated with osteoporosis. To name a few, these include a low dietary calcium intake, a sedentary lifestyle, cigarette smoking and alcoholism. There is no doubt that public health policies should address these issues. What is more doubtful is the extent to which individuals within populations can be persuaded to change their behaviour, and to sustain such changes.
(http://annals.edu.sg/pdfJan02/LauEMC.pdf)
The relationship between tobacco and osteoporosis can be found at this website:
http://www.who.int/tobacco/research/osteoporosis/en/
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