Changes in Body Mass Index and Outcomes After Kidney Transplant: A Single-Center, Retrospective, Observational Study.

OBJECTIVES: We aimed to describe changes in body mass index after kidney transplant and to assess how these changes influence long-term outcomes. MATERIALS AND METHODS: Data were collected from kidney transplant recipients seen at our center between January 2007 and July 2016. Changes in body mass index over the posttransplant period were modeled using a generalized estimating equation, with changes calculated for each patient from pretransplant to 6 months posttransplant. Calculations were then categorized into 3 body mass index groups: stable (change of ± 1.5 kg/m² or less), reduced (reduction of > 1.5 kg/m²), and increased (increase of > 1.5 kg/m²). Outcomes among groups were compared. RESULTS: Among 1344 total patients, the geometric mean pretransplant body mass index was 27.3 kg/m². This declined significantly (P .05). CONCLUSIONS: Our data demonstrated that body mass index was significantly reduced in the first month after kidney transplant before increasing to pretransplant levels during years 3 to 5. Furthermore, patients who retained decreased levels at 6 months had impaired graft function in long-term follow-up. These observations conflict with the existing literature and warrant further investigations.