Shotaro Ohnaka1, Shunsuke Yamada2, Hiroaki Tsujikawa3, Hokuto Arase4, Masatomo Taniguchi5, Masanori Tokumoto6, Kazuhiko Tsuruya7, Toshiaki Nakano8, Takanari Kitazono9. 1. Division of Nephrology, Tagawa Municipal Hospital, Fukuoka, Japan. Electronic address: ohnaka.kyu@gmail.com. 2. Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: ana65641@nifty.com. 3. Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: md102059@yahoo.co.jp. 4. Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: arasehokuto@gmail.com. 5. Fukuoka Renal Clinic, Fukuoka, Japan. Electronic address: macha1214@gmail.com. 6. Department of Internal Medicine, Fukuoka Dental College, Fukuoka, Japan. Electronic address: tokumoto@college.fdcnet.ac.jp. 7. Department of Nephrology, Nara Medical University, Nara, Japan. Electronic address: tsuruya@naramed-u.ac.jp. 8. Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: toshink@med.kyushu-u.ac.jp. 9. Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: kitazono@intmed2.med.kyushu-u.ac.jp.
Abstract
BACKGROUND & AIMS: Normalized protein catabolic rate (nPCR) is used as a surrogate for daily dietary protein intake and nutritional status in patients receiving maintenance hemodialysis. It remains uncertain whether the nPCR level is associated with the incidence of bone fracture. METHODS: A total of 2869 hemodialysis patients registered in the Q-Cohort Study, a multicenter, prospective, observational study, were followed up for 4 years. The primary outcome was bone fracture at any site. The main exposure was the nPCR level at baseline. Patients were assigned to four groups based on their baseline nPCR levels (G1: <0.85, G2: 0.85≤, <0.95, G3: 0.95≤, <1.05 [reference], G4: ≥1.05 g/kg/day). We examined the relationship between the nPCR levels and the risk for bone fracture using Cox proportional hazards models. RESULTS: During the follow-up period, 136 patients experienced bone fracture at any site. In the multivariable analyses, the risk for bone fracture was significantly higher in the lowest (G1) and highest (G4) nPCR groups than the reference (G3) group (hazard ratio [95% confidence intervals]: G1, 1.93 [1.04-3.58]; G2, 1.27 [0.67-2.40]; G3 1.00 (reference); G4, 2.21 [1.25-3.92]). The association remained almost unchanged, even when patients were divided into sex-specific nPCR quartiles, when analysis was limited to patients with a dialysis vintage ≥2 years, assumed to have lost residual kidney function, or when a competing risk model was applied. CONCLUSIONS: Our results suggest that both lower and higher nPCR levels are associated with an increased risk for bone fracture in hemodialysis patients.
BACKGROUND & AIMS: Normalized protein catabolic rate (nPCR) is used as a surrogate for daily dietary protein intake and nutritional status in patients receiving maintenance hemodialysis. It remains uncertain whether the nPCR level is associated with the incidence of bone fracture. METHODS: A total of 2869 hemodialysis patients registered in the Q-Cohort Study, a multicenter, prospective, observational study, were followed up for 4 years. The primary outcome was bone fracture at any site. The main exposure was the nPCR level at baseline. Patients were assigned to four groups based on their baseline nPCR levels (G1: <0.85, G2: 0.85≤, <0.95, G3: 0.95≤, <1.05 [reference], G4: ≥1.05 g/kg/day). We examined the relationship between the nPCR levels and the risk for bone fracture using Cox proportional hazards models. RESULTS: During the follow-up period, 136 patients experienced bone fracture at any site. In the multivariable analyses, the risk for bone fracture was significantly higher in the lowest (G1) and highest (G4) nPCR groups than the reference (G3) group (hazard ratio [95% confidence intervals]: G1, 1.93 [1.04-3.58]; G2, 1.27 [0.67-2.40]; G3 1.00 (reference); G4, 2.21 [1.25-3.92]). The association remained almost unchanged, even when patients were divided into sex-specific nPCR quartiles, when analysis was limited to patients with a dialysis vintage ≥2 years, assumed to have lost residual kidney function, or when a competing risk model was applied. CONCLUSIONS: Our results suggest that both lower and higher nPCR levels are associated with an increased risk for bone fracture in hemodialysis patients.