Poor kidney function increases hip fracture risk
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A lower estimated glomerular filtration rate and albuminuria were shown to have a “synergistic effect” in increasing risk for hip fracture among a cohort of Korean adults, according to findings published in the Journal of Bone and Mineral Research.
“Only a few studies have examined the associations between albuminuria and hip fracture risk,” Sang-Wook Yi, MD, PhD, professor in the department of preventive medicine and public health at Catholic Kwandong University College of Medicine, South Korea, and colleagues wrote in the study background. “One study conducted in a population at high risk for cardiovascular disease suggested a higher risk of hip fractures among participants with albuminuria. Another study showed that albuminuria was associated with a higher risk of hip fracture in older women, but not in men. To date, limited data exist regarding the combined effects of eGFR and albuminuria categories on the risk of hip fracture in the general population.”
Renal decline and fracture risk
In a prospective study, Yi and colleagues analyzed data from 352,624 unselected Korean adults who participated in health examinations from 2008-2009 to 2013 (mean baseline age, 59 years; mean BMI, 24 kg/m2; mean eGFR, 82.7 mL/min/1.73 m2). Researchers assessed kidney function by creatinine-based eGFR and albuminuria using urine reagent strip results. The incidence of hip fracture was examined by hospital discharge records. Researchers used Cox proportional hazard models to estimate HRs for hip fracture based on kidney function.
Within the cohort, 92.3% of adults had an eGFR of at least 60 mL/min/1.73 m2, 6.6% had an eGFR between 45 mL/min/1.73 m2 and 59 mL/min/1.73 m2, 0.9% had an eGFR between 30 mL/min/1.73 m2 and 44 mL/min/1.73 m2, and 0.2% had an eGFR between 15 mL/min/1.73 m2 and 29 mL/min/1.73 m2. Most participants (94%) had normal to mild albuminuria, 4.1% had moderate albuminuria and 1% had severe albuminuria. During a mean follow-up of 4 years, 1,177 adults sustained a hip fracture (716 women).
Researchers found that lower eGFR and more severe albuminuria were associated with a higher risk for hip fracture. Compared with adults with an eGFR of at least 60 mL/min/1.73 m2, HRs for hip fracture were 1.89 (95% CI, 1.47-2.43) among participants with an eGFR between 30 mL/min/1.73 m2 and 44 mL/min/1.73 m2 and 3.75 (95% CI, 2.3-6.11) among participants with an eGFR between 15 mL/min/1.73 m2 and 29 mL/min/1.73 m2.
Compared with adults without albuminuria, HRs for hip fracture were 1.3 for moderate albuminuria (95% CI, 1.02-1.65) and 1.58 for severe albuminuria (95% CI, 1.07-2.35).
For adults in the same eGFR category, risk for hip fracture was higher among those with albuminuria vs. those without albuminuria. For adults with an eGFR between 30 mL/min/1.73 m2 and 44 mL/min/1.73 m2, HRs for hip fracture were 3.3 (95% CI, 2.03-5.35) and 1.75 (95% CI, 1.32-2.32), respectively, for those with and without albuminuria. However, for those with an eGFR between 15 mL/min/1.73 m2 and 29 mL/min/1.73m2, the HR for hip fracture rose sharply for adults with albuminuria (HR = 7.84; 95% CI, 4.06-15.15) vs. those without albuminuria (HR = 2.72; 95% CI, 1.35-5.47).
Role of albumin
In subgroup analyses to evaluate the association between eGFR and hip fracture risk, researchers found that adults without albuminuria had only a 16% increased risk for hip fracture per 10 mL/min/1.73 m2 decrease in eGFR; however, those with moderate and severe albuminuria had 49% and 65% increased risk for hip fracture, respectively, per 10-unit decrease in eGFR (P for interaction = .016).
“The effects of each 10 mL/min/1.73 m2 decrease in the eGFR were stronger with advancing albuminuria severity, suggesting a supra-multiplicative interaction between these two factors,” the researchers wrote.
How bone mineral density might mediate the observed association between renal function and hip fracture risk could not be investigated, according to the researchers, as such measurements were not available for the cohort.
“In this prospective study, an eGFR less than 60 mL/min/1.73 m2 and albuminuria were associated with a higher risk of hip fracture in men and women,” the researchers wrote. “Additionally, albuminuria and lower eGFR had a synergistic effect on increasing the risk of hip fractures. Therefore, more efforts to prevent hip fracture should be made in those with both albuminuria and a low GFR.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.
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