Pretransplant Osteoporosis and Osteopenia are Risk Factors for Fractures After Kidney Transplantation

The comprehensive incidence and risk factors of fracture in kidney transplant recipients: A meta-analysis

AIM

Kidney transplant recipients are at high risk of fracture due to many factors such as nutritional status, hyperparathyroidism, acidosis and steroid administration. The current meta-analysis aimed to comprehensively analyse the incidence and risk factors of fracture in kidney transplant recipients.

METHODS

A systematic search on Embase, Web of Science, PubMed and Cochrane Library until November 2023 was performed. RStudio software was used to analyse data.

RESULTS

Twenty-eight eligible studies containing 310 530 kidney transplant recipients were included in the analysis. The pooled incidence of fracture was 10% (95% confidence interval [CI]: 7%-13%) generally. When divided by regions, it was further observed that the pooled incidence of fracture was 13% (95% CI: 9%-17%) in Europe, 11% (95% CI: 6%-16%) in North America, 7% (95% CI: 3%-11%) in Asia. Regarding the risk factors, pooled analysis revealed that age of recipient (hazard ratio [HR] = 1.50, 95% CI: 1.17-1.91), female sex (HR = 1.45, 95% CI: 1.36-1.53), pretransplantation diabetes (HR = 1.76, 95% CI: 1.58-1.97), pretransplantation fracture history (HR = 2.28, 95% CI: 1.86-2.78), dialysis duration (HR = 1.09, 95% CI: 1.01-1.17) and deceased donor (HR = 1.21, 95% CI: 1.05-1.39) related to higher risk of fracture. The general quality of included studies was acceptable, and no publication bias existed except for the analysis between age of recipient and fracture incidence; further trim and fill method indicated age of recipient showed a correlation trend with the fracture incidence without the statistical significance.

CONCLUSION

The pooled incidence of fracture reaches 10% in kidney transplant recipients, which relates to age of recipient, female sex, pretransplantation diabetes or fracture history, dialysis duration and decease donor.

Bone and Mineral Disorder in Renal Transplant Patients: Overview of Pathology, Clinical, and Therapeutic Aspects

Renal transplantation (RTx) allows us to obtain the resolution of the uremic status but is not frequently able to solve all the metabolic complications present during end-stage renal disease. Mineral and bone disorders (MBDs) are frequent since the early stages of chronic kidney disease (CKD) and strongly influence the morbidity and mortality of patients with CKD. Some mineral metabolism (MM) alterations can persist in patients with RTx (RTx-p), as well as in the presence of complete renal function recovery. In those patients, anomalies of calcium, phosphorus, parathormone, fibroblast growth factor 23, and vitamin D such as bone and vessels are frequent and related to both pre-RTx and post-RTx specific factors. Many treatments are present for the management of post-RTx MBD. Despite that, the guidelines that can give clear directives in MBD treatment of RTx-p are still missed. For the future, to obtain an ever-greater individualisation of therapy, an increase of the evidence, the specificity of international guidelines, and more uniform management of these anomalies worldwide should be expected. In this review, the major factors related to post-renal transplant MBD (post-RTx-MBD), the main mineral metabolism biochemical anomalies, and the principal treatment for post-RTx MBD will be reported.

Quantitative Ultrasound of Phalanx in Primary and Secondary Osteoporosis: Mini-review and Practical Experience

Objective:

Dual x-ray absorptiometry (DXA) is gold standard of bone densitometry, but quantitative ultrasound (QUS) of bone is less expensive and portable. This study was designed to assess its usefulness in secondary osteoporosis diagnosis.

Materials and Methods:

There were 200 secondary osteoporosis cases (rheumatoid arthritis, hemodialysis, kidney transplant patients, and levothyroxine users) and of those, their phalanx QUS results were compared with normal controls. Also, the QUS and DXA results were compared to find any correlation of these methods for diagnosing osteoporosis.

Results:

There was not significantly different results compared with normal controls, except for those of hemodialysis patients ( P = .00). Also, the comparison of QUS with DXA results showed no significant correlation except in hemodialysis patients, in both spinal and femoral regions ( P = .023 and .21, respectively), as well as the levothyroxine group’s spinal region ( P = .005).

Conclusion:

These results suggest that QUS of phalanx may be useful in screening secondary osteoporosis but for establishment of diagnosis, DXA measurements are still needed.

Mineral Bone Disorders in Kidney Transplantation

Bone disease after kidney transplantation is associated with an increased risk of fractures, morbidity, and mortality. Its pathophysiology is complex, involving multiple contributors including pretransplant bone disease, immunosuppressive medications, and changes in the parathyroid-bone-kidney axis. Risk scores, bone turnover markers, and noninvasive imaging modalities are only able to partially predict the fracture risk in kidney transplant recipients. The optimal management of bone disease after kidney transplantation has not yet been established, with only a limited number of randomized clinical trials evaluating the efficacy of treatment regimens in kidney transplant recipients. This review focuses on the pathophysiology, evaluation, prevention, and treatment of post-kidney transplant mineral and bone disease as guided by recent evidence.

Risk Factors and Management of Osteoporosis Post-Transplant

Bone and mineral disorders are common after organ transplantation. Osteoporosis post transplantation is associated with increased morbidity and mortality. Pathogenesis of bone disorders in this particular sub set of the population is complicated by multiple co-existing factors like preexisting bone disease, Vitamin D deficiency and parathyroid dysfunction. Risk factors include post-transplant immobilization, steroid usage, diabetes mellitus, low body mass index, older age, female sex, smoking, alcohol consumption and a sedentary lifestyle. Immunosuppressive medications post-transplant have a negative impact on outcomes, and further aggravate osteoporotic risk. Management is complex and challenging due to the sub-optimal sensitivity and specificity of non-invasive diagnostic tests, and the underutilization of bone biopsy. In this review, we summarize the prevalence, pathophysiology, diagnostic tests and management of osteoporosis in solid organ and hematopoietic stem cell transplant recipients.