A secular trend in hip fracture incidence in East Germany.

The central Inpatient Register of the former German Democratic Republic was used to study the population-based epidemiology of hip fractures among 16.5 million East Germans. Incidence rates for hospital discharges for proximal femoral fractures for the age group 60 years and over were calculated for the years 1971 to 1989, the year before unification. Incidence rates for 1989 are similar to figures reported from the UK and The Netherlands, but lower than Scandinavian rates. A decrease in the admission rate was noted from 1971 to 1974 of 4.5% each year on average, and an increase from 1974 onwards of 4.4% on average. This change was observed to a different extent in all age groups. The female:male ratio of the standardized discharge incidence was stable at 2.3:1 and the female:male ratio of manifest cases increases from 4.1:1 in 1971 to 5.1:1 in 1989. An exponential increase in the incidence rates was observed with age. This apparent rate overestimated both the rate for true incident cases (by about 25-30%, if adjustments are made for readmissions and transfers) and their trend. Adjusted estimates for incident fractures show an increase of 2% annually. Cohort effects due to changed selective forces appear to be one reasonable causal explanation.