Hip Fracture Trends in Japanese Dialysis Patients, 2008-2013

Abstract

Background: Contrary to observations of decreasing rates in Western nations for the past 2 decades, age-adjusted rates of hip fracture in the general population in Japan have continually increased. This study aimed to analyze recent changes in trends of hip fracture incidence among Japanese dialysis patients between 2008 and 2013.

Study design, setting, & participants: Using data from the Japanese Society for Dialysis Therapy Renal Data Registry database from 2007 to 2013, we created a point-prevalent study cohort for each study year. Prevalent dialysis cohorts included patients 20 years or older without a history of hip fracture who were receiving maintenance dialysis in Japan on December 31 of each year.

Factors: Age, sex, and calendar year.

Outcomes: Hip fracture incidence rates.

Measurements: Unadjusted hip fracture rates were estimated using number of events per 1,000 patient-years in each year and then standardized for age to the 2013 dialysis population. Average annual percentage of change in rates and corresponding 95% CI were computed for trend by joinpoint regression analysis.

Results: During the study period, 6,615 and 4,963 hip fractures were recorded among female and male dialysis patients, respectively. Age-standardized hip fracture rates decreased steadily from 2008 (21.1/1,000 patient-years) to 2013 (17.7/1,000 patient-years) among women, but remained constant from 2008 (8.6/1,000 patient-years) through 2013 (8.2/1,000 patient-years) among men. Decreases in the joinpoint trend for hip fracture were significant among female (-3.6% [95% CI, -6.9 to -0.2] per year), but not among male, dialysis patients (-1.4% [95% CI, -5.7 to 3.0] per year) from 2008 through 2013.

Limitations: Only the first hip fracture event was considered in calculations of fracture rates.

Conclusions: In contrast to the increasing incidence of hip fracture in the general Japanese population, we found that the incidence of hip fracture in Japanese dialysis patients between 2008 and 2013 decreased among women, but did not change in men.

Keywords: Hip fracture; Japan; dialysis; dialysis patients; end-stage renal disease (ESRD); incidence rates; joinpoint regression; secular trends; sex difference.