title: Bone Density, Microarchitecture, and Tissue Quality Long-term After Kidney Transplant.
abstract: Bone mineral density (BMD) measured by dual-energy x-ray absorptiometry is used to assess bone health in kidney transplant recipients (KTR). Trabecular bone score and in vivo microindentation are novel techniques that directly measure trabecular microarchitecture and mechanical properties of bone at a tissue level and independently predict fracture risk. We tested the bone status of long-term KTR using all 3 techniques.
  
  
  
  Cross-sectional study including 40 KTR with more than 10 years of follow-up and 94 healthy nontransplanted subjects as controls. Bone mineral density was measured at lumbar spine and the hip. Trabecular bone score was measured by specific software on the dual-energy x-ray absorptiometry scans of lumbar spine in 39 KTR and 77 controls. Microindentation was performed at the anterior tibial face with a reference-point indenter device. Bone measurements were standardized as percentage of a reference value, expressed as bone material strength index (BMSi) units. Multivariable (age, sex, and body mass index-adjusted) linear regression models were fitted to study the association between KTR and BMD/BMSi/trabecular bone score.
  
  
  
  Bone mineral density was lower at lumbar spine (0.925 ± 0.15 vs 0.982 ± 0.14; P = 0.025), total hip (0.792 ± 0.14 vs 0.902 ± 0.13; P < 0.001), and femoral neck (0.667 ± 0.13 vs 0.775 ± 0.12; P < 0.001) in KTR than in controls. BMSi was also lower in KTR (79.1 ± 7.7 vs 82.9 ± 7.8; P = 0.012) although this difference disappeared after adjusted model (P = 0.145). Trabecular bone score was borderline lower (1.21 ± 0.14 vs 1.3 ± 0.15; adjusted P = 0.072) in KTR.
  
  
  
  Despite persistent decrease in BMD, trabecular microarchitecture and tissue quality remain normal in long-term KTR, suggesting important recovery of bone health.
authors.affiliation: 1 Department of Nephrology, Hospital del Mar, Autonomous University of Barcelona, Barcelona, Spain. 2 Institut Mar d'Investigacions Mediques, Barcelona, Spain. 3 REDINREN, Instituto Carlos III, Madrid, Spain. 4 Department of Internal Medicine, Hospital del Mar, Autonomous University of Barcelona, Spain. 5 RETICEF, Instituto Carlos III Madrid, Spain. 6 Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.
authors.forename: María José
authors.initials: MJ
authors.lastname: Pérez-Sáez
authors.forename: Sabina
authors.initials: S
authors.lastname: Herrera
authors.forename: Daniel
authors.initials: D
authors.lastname: Prieto-Alhambra
authors.forename: Xavier
authors.initials: X
authors.lastname: Nogués
authors.forename: María
authors.initials: M
authors.lastname: Vera
authors.forename: Dolores
authors.initials: D
authors.lastname: Redondo-Pachón
authors.forename: Marisa
authors.initials: M
authors.lastname: Mir
authors.forename: Roberto
authors.initials: R
authors.lastname: Güerri
authors.forename: Marta
authors.initials: M
authors.lastname: Crespo
authors.forename: Adolfo
authors.initials: A
authors.lastname: Díez-Pérez
authors.forename: Julio
authors.initials: J
authors.lastname: Pascual
mesh_terms: D015502:Absorptiometry, Photon; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005240:Feasibility Studies; D006304:Health Status; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000453:epidemiology; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000453:epidemiology / Q000601:surgery*; D016030:Kidney Transplantation / Q000009:adverse effects; D016014:Linear Models; D016015:Logistic Models; D008159:Lumbar Vertebrae / Q000187:drug effects / Q000503:physiopathology*; D015999:Multivariate Analysis; D010384:Pelvic Bones / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010865:Pilot Projects; D015995:Prevalence; D020127:Recovery of Function; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D017741:Survivors; D013997:Time Factors; D016896:Treatment Outcome; D014808:Vitamin D Deficiency / Q000453:epidemiology