Geovariation in fracture risk among patients receiving hemodialysis

James B. Wetmore, Jiannong Liu, Heidi S. Wirtz, David T. Gilbertson, Kerry Cooper, Kimberly M. Nieman, Allan J. Collins, Brian D. Bradbury

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Background and objectives Fractures are amajor source of morbidity and mortality in patients receiving dialysis. We sought to determine whether rates of fractures and tendon ruptures vary geographically. Design, setting, participants, & measurements Data from the US Renal Data System were used to create four yearly cohorts, 2007-2010, including all eligible prevalent patients on hemodialysis in the United States on January 1 of each year. A secondary analysis comprising patients in a large dialysis organization conducted over the same period permitted inclusion of patient-level markers ofmineral metabolism. Patients were grouped into 10 regions designated by theCenters forMedicare andMedicaid Services and divided by latitude into one of three bands: south, <35°; middle, 35° to,<40°; and north, ≥ 40°. Poisson regression was used to calculate unadjusted and adjusted region-level rate ratios for events. Results Overall, 327,615 patients on hemodialysis were included. Mean (SD) age was 61.8 (15.0) years old, 52.7% were white, and 55.0% were men. During 716,962 person-years of follow-up, 44,014 fractures and tendon ruptures occurred, the latter being only 0.3% of overall events. Event rates ranged from 5.36 to 7.83 per 100 person-years, a 1.5-fold rate difference across regions. Unadjusted region-level rate ratios varied from 0.83 (95% confidence interval, 0.81 to 0.85) to 1.20 (95% confidence interval, 1.18 to 1.23), a 1.45-fold rate difference. After adjustment for a wide range of case mix variables, a 1.33-fold variation in rates remained. Rates were higher in north and middle bands than the south (north rate ratio, 1.18; 95% confidence interval, 1.13 to 1.23; middle rate ratio, 1.13; 95% confidence interval, 1.10 to 1.17). Latitude explained 11% of variation, independent of region. A complementary analysis of 87,013 patients from a large dialysis organization further adjusted for circulating mineral metabolic parameters and protein energy wasting yielded similar results. Conclusions Rates of fractures vary geographically in theUnited States dialysis population, even after adjustment for known patient characteristics. Latitude seems to contribute to this phenomenon, but additional analyses exploring whether other factors might influence variation are warranted.

Original languageEnglish (US)
Pages (from-to)1413-1421
Number of pages9
JournalClinical Journal of the American Society of Nephrology
Volume11
Issue number8
DOIs
StatePublished - 2016

Bibliographical note

Funding Information:
The authors thank Chronic Disease Research Group colleagues Delaney Berrini for manuscript preparation and Nan Booth for manuscript editing. This studywas supported by a research contract from Amgen, Inc. (Thousand Oaks, CA). The contract provides for the Minneapolis Medical Research Foundation authors to have final determination of manuscript content. The data reported here have been supplied by the US Renal Data System and a large national dialysis provider. The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy or interpretation of the US Government.

Keywords

  • ESRD
  • Follow-Up Studies
  • Fracture
  • Humans
  • Medicaid
  • Medicare
  • Morbidity
  • Prevalence
  • geographic variation
  • hemodialysis

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