Geovariation in Fracture Risk among Patients Receiving Hemodialysis

Abstract

Background and objectives Fractures are a major 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 of mineral metabolism. Patients were grouped into 10 regions designated by the Centers for Medicare and Medicaid 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 the United 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.

Early withdrawal and non‐withdrawal death in the months following hemodialysis initiation: A retrospective cohort analysis

“…Variables selected for analysis were based on clinical insights and concordance with previous studies . Age, race, sex, and cause of ESRD (derived from the USRDS standard analytic files) were included, as were major comorbid conditions, ascertained over the year preceding hemodialysis initiation by the presence of one or more inpatient or two or more outpatient/Part B claims separated by at least 30 days . The conditions assessed and the associated identification approach are shown in Supporting Information Methods S1 and Table S1.…”

“…To create a score that might reflect difficult‐to‐define phenomena such as impaired functional status, we employed a variation of a previously developed claims‐based algorithm, which eliminated a history of myocardial infarction or stroke from the score (as these were accounted for separately as model covariates).…”

“…14,15,19 Age, race, sex, and cause of ESRD (derived from the USRDS standard analytic files) were included, as were major comorbid conditions, ascertained over the year preceding hemodialysis initiation by the presence of one or more inpatient or two or more outpatient/Part B claims separated by at least 30 days. 29,30 The conditions assessed and the associated identification approach are shown in Supporting Information Methods S1 and Table S1. We also included duration of nephrology care prior to hemodialysis initiation, initial hemodialysis access, and time spent hospitalized or in a skilled nursing facility (SNF) in the year preceding hemodialysis initiation.…”

Molecular Abnormalities Underlying Bone Fragility in Chronic Kidney Disease

“…Falls are especially common in older CKD patients [18]. Lack of exposure to sunlight, which contributes to muscle strength, may be a risk factor, because the risk for hip fractures tends to be higher in high-latitude regions of the United States [19]. Despite the high prevalence of hip fractures, clinical studies have failed to elucidate why falling affects the risk for hip fractures but not fractures of other parts of the body such as vertebrae and wrist.…”

Chronic kidney disease and fragility fracture

“…The risk is 4–13 times higher in dialysis patients compared to the general population. The risk tends to be higher in high-latitude regions in the United States [ 13 ]. In Japan, the risk is higher in western prefectures [ 14 ], indicating that sunlight has little to do with the HFx risk.…”