International variation in the incidence of hip fractures: cross-national project on osteoporosis for the World Health Organization Program for Research on Aging.

A cross-national study of hip fracture incidence was carried out in five geographic areas--Beijing, China; Budapest, Hungary; Hong Kong; Porto Alegre, Brazil; and Reykjavik, Iceland--during the years 1990-1992. Cases of hip fracture among women and men of age 20 years and older were identified using hospital discharge data in conjunction with medical records, operating room logs, and radiology logs. Estimated incidence rates varied widely, with Beijing reporting the lowest rates (age-adjusted rate per 100,000 population for men 20 years and older = 45.4; women = 39.6) and Reykjavik the highest rates (man = 141.3; women = 274.1). Rates were higher for women than for men in every area except Beijing. In every area except Budapest, review of the operating room or radiology logs identified additional cases that were not reported in the discharge list, increasing the estimated number of hip fractures by 11% to 62%, depending on the area. Review of medical records identified miscoding of hip fractures (ICD 9820) as 'shaft of femur and other femur fractures' (ICD 9821) in the discharge lists of every area except Budapest, increasing the estimated number of hip fractures by 1% to 30%. The final estimates of hip fracture incidence taking into account all investigated sources of undercount and overcount ranged from 15% lower to 89% higher than an estimate based on the discharge diagnoses alone. Although these results indicate substantial limitations in relying on hospital discharge data alone to estimate hip fracture incidence rates, the extent of errors found in the discharge lists is smaller than the large international variation found here and previously reported in incidence rates. The findings support the conclusion that the differences reported among countries mainly reflect genuine variation in the hip fracture incidence rates.

International comparison of hip fracture rates in 1988-89.

A comparison of hip fracture rates among nine countries (Canada, Chile, Finland, Hong Kong, Scotland, Sweden, Switzerland, the United States and Venezuela) was made using national hospital discharge data for the same time interval. The rates increased by age and were higher for females than males in all nine countries. When based on overall discharge rates, the incidence of hip fracture appeared high in three European countries (Finland, Scotland and Sweden) relative to the other countries. However, when transfer cases were removed and adjustments made for differences in case definition, the risk of hip fracture for both men and women was much similar among the four European and two North American countries, but higher than in Hong Kong. Rates of fracture were lowest in Venezuela and Chile, varying from three to 11 times less than for residents of the other seven countries. Although there are limitations in using hospital discharge data as a measure of incidence, the wide variation in the risk of hip fracture across the nine countries appears real but differences between North American and north European countries may not be as great as previously reported. Such cross-national comparisons may help clarify different etiologic hypotheses.