Cyclosporine use and male gender are independent determinants of avascular necrosis after kidney transplantation: a cohort study.

BACKGROUND

Kidney transplant recipients (KTRs) are at increased risk of avascular necrosis (AVN) due to bone disorder, steroid use and common comorbidities. However, knowledge on risk factors and outcomes of AVN among KTRs in the modern era of immunosuppression remains scarce.

METHODS

We analysed 765 KTRs between 2001 and 2013 for AVN. Cases of symptomatic AVN were diagnosed by hip X-ray, radioisotope bone scan or magnetic resonance imaging. We evaluated risk factors and clinical characteristics of AVN.

RESULTS

KTRs showed a constant incidence rate of AVN of 4.1% at 10 years after transplantation. The use of cyclosporine compared with tacrolimus was identified as an independent risk factor, with a rate of 8.0% compared with 2.7% at 10 years (P < 0.01). In addition, male gender was independently associated with AVN (P = 0.047). Eighty-three per cent of AVN cases were of the femoral head and treated operatively. None of the operated KTRs experienced complications in the long term. Thirty-three per cent of KTRs had bilateral AVN. Ninety-two per cent of KTRs showed AVN at the allograft side.

CONCLUSIONS

The decreasing incidence of AVN may be attributed to the replacement of cyclosporine by tacrolimus over the last decade. Our data raise the hypothesis of an ischaemic steal syndrome due to the allograft kidney impacting AVN at the allograft side.