Epidemiology of hip fracture in Japan: incidence and risk factors

Hip fracture is the most serious complication of osteoporosis and has been recognized as a major public health problem. The prevention of hip fractures is an high-priority issue because of the rapid increase of the number of elderly people in Japan. The General Research Committee for the Prevention and Treatment of Osteoporosis in Silver Health Science Researches sponsored by the Ministry of Health and Welfare (Director, Hajime Orimo) first undertook a nationwide survey of femoral neck fracture in 1987. This nationwide survey has been continued every 5 years, in 1992, 1997, and 2002. The total number of new cases was nearly 120,000 in the latest survey, and has been rising in every survey. Total number of new cases was about 1.4 times the baseline 1987 figures in 1992, 1.7 times in 1997, and 2.2 times in 2002. The total number of new female patients was about three times higher than that of new male patients, a finding identical to those of the previous surveys. The incidences of hip fracture (per 10,000) according to sex and age was increased in both men and women, particularly among individuals 80 years old or over. The Epidemiological Research Group on Osteoporosis, Ministry of Health and Welfare (Chairman; Hajime Orimo) undertook a nation-wide case-control study to clarify the risk factors for hip fractures among Japanese in 1994. Cases of hip fracture in people aged 65-89 were selected from 21 hospitals in seven areas of Japan. Two sex- and age-matched controls were selected from the same residential area for each case using resident registration lists. During this 1-year survey, 249 cases of hip fractures (43 men and 206 women) were reported. The following risk factors for hip fractures were identified using multivariate analysis: past history of stroke with hemiplegia, sleep disturbance, sleeping in a Western-style bed, and drinking more than 3 cups of coffee daily.