Osteoporosis and fracture risk in older people.

Until the 1940s, when Albright associated osteoporosis with a defect of bone anabolism, it was not considered a disease entity but an inevitable consequence of the ageing process for which there was little remedy.1 Bisphosphonates, fi rst synthesised in the 1800s but in clinical use only since the 1960s, demonstrated that this process of age-related decline in bone was, in fact, modifi able.2 More recently, a wealth of basic and clinical research has greatly enhanced our understanding of the complexity of bone metabolism, enabling the development of novel therapeutic strategies. The resultant reduction in fracture risk is greatest in those with more severe osteoporosis, suggesting that older people can have considerable gains from bone-sparing treatments. Osteoporosis, now acknowledged as the most prevalent bone disorder in the world, is characterised by low bone mass, microarchitectural deterioration of bone tissue and decreased bone strength. Adult bone mass results from peak bone mass achieved during adolescence and subsequently maintained until perturbations in the bone remodelling cycle – usually a very tightly coupled process – occur and alter the balance between bone-forming osteoblasts and bone-resorbing osteoclasts. In a normal remodelling cycle, the amount of bone lost is the same as the amount of new bone formed. When this process becomes ‘uncoupled’ – as is the case in people with oestrogen defi ciency, high levels of glucocorticoids, changes in serum calcium levels, fl uctuations in levels of parathyroid hormone (PTH) and changes in levels of growth hormone – there is a net loss of bone. Estimates indicate that 50% of women and 20% of men aged over 50 years will experience an osteoporosis-related fracture; hip fracture is the most devastating of these due to the consequent disability, mortality and costs – both personal and societal. Due to changing population demographics, estimates suggest a doubling of the number of people with osteoporosis in the next 20 years. Consequently, an exponential increase in the numbers of fractures is anticipated, with an inevitable increased fi nancial burden for healthcare systems – the total economic burden of osteoporosis in the European Union in 2010 was estimated at €39 billion (about £32 billion).3 Without taking into account the personal cost to the individual, one can see why prevention and treatment of osteoporosis should be a priority for all those who care for older people. Osteoporosis is underdiagnosed and undertreated, particularly in those aged over 75 years, in whom treatment is probably most benefi cial and cost effective.4 This fact suggests that treatment of the older cohort remains a challenge, not helped by the limited representation of older adults in major trials of osteoporosis treatments.