Patients with chronic kidney disease (CKD) stage 5D (receiving dialysis) have heightened fracture risk and post-fracture mortality, and those with type 1 diabetes mellitus (T1DM) are at even greater risk. Bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) shows inferior fracture prediction in CKD-5D than in the general population. Recently we showed DXA-derived trabecular bone score (TBS) and hip structural analysis (HSA) parameters: femoral neck cortical thickness (CT) and the buckling ratio (BR; an index of femoral neck instability) to be markedly abnormal and associated with prevalent fracture in CKD-5D.
This study assessed TBS and HSA parameters in patients with T1DM and CKD-5D at the time of simultaneous pancreas kidney (SPK) transplantation compared with kidney only transplantation without T1DM (KTx). Of 226 patients, 64.8% were male and 58 (26%) were SPK recipients. SPK recipients were younger (42.3±7.6 vs. 50.8±13.8 years), had shorter dialysis duration (23±20 vs. 42±39 months), higher HbA1c (8±1.5% vs. 5.5±1.0%) and lower BMI (24.7±5.9 vs. 27.1± 4.8). SPK recipients had lower BMD Z-Scores at the spine, hip and ultradistal radius (all p≤0.001), but not at the 1/3 radius (p=0.298). SPK recipients had lower TBS (1.316±0.104 vs. 1.366±0.123; p=0.006), higher buckling ratios (10.5±7.5 vs. 7.7±4; p<0.001) and lower femoral neck, calcar and shaft CT (p=0.047, p=0.041 and p<0.001 respectively). In regression analyses adjusted for age, gender, dialysis vintage and weight, T1DM SPK transplant predicted a higher BR (β= -0.243= , p<0.001), lower femoral neck CT (β= 0.242, p<0.001) and lower femoral shaft CT (β=0.241, p <0.001), but not calcar CT.
Patients with T1DM undergoing SPK transplantation have reduced TBS, increased BR and reduced CT compared with KTx patients despite their younger age and shorter dialysis vintage. The utility of these DXA-derived parameters for fracture prediction should be assessed prospectively in patients with T1DM, CKD-5D and following transplantation.