[Epidemiology of osteoporosis: incidence, prevalence, and prognosis]

Though the exact and cumulative incidence of osteoporosis has not been examined, using the criteria that osteoporosis is defined by a decrease of bone mineral density (BMD) below 70% from young adult mean (YAM), the prevalence of osteoporosis among the Japanese women can be estimated as to be more than either 30% (by spinal BMD) or 37% (by femoral BMD) in 60's, 37% or 64% in 70's, and 42% or 90% in 80's, respectively. The total number of osteoporosis among the women with age 50 and over can be also estimated as to be either about 5 million (by spinal BMD) or 8.5 million (by forearm BMD). National survey shows that the ratio of people receiving treatment for osteoporosis is 34.5 per 1,000 among the elderly with age 65 and over. In addition, both functional transition and survival rate of discharged patients with osteoporotic hip fracture are discussed as prognosis of osteoporosis.