Post-kidney transplant weight change as marker of poor survival outcomes

Background. There are few studies on the associations of postkidney transplant weight change on survival. Weight change in different posttransplant periods may have different causes and implications. We used the Australian and New Zealand Dialysis and Transplant Registry data to examine these issues. Methods. All adult white primary kidney transplant recipients from April 1991 to December 2004 were included. The associations of first (year 1, n=3899) and second (year 2, n=3419) year weight change with subsequent graft and patient survival were analyzed using multivariable Cox regression. Results. Weight gain 10% to 19.9% in year 1 and stable weight (0%-4.9% gain) in year 2 were associated with the best outcomes. Weight loss more than 5% was associated with subsequent death (year 1 adjusted hazard ratio [aHR] = 1.64 [1.08-2.48], P=0.019; year 2 aHR=2.09 [1.44-3.02], P=0.013) but not death-censored graft loss. Weight gain more than or equal to 20% in year 1 and more than or equal to 10% weight gain in year 2 were also associated with subsequent death (year 1 aHR=1.78 [1.13-2.81], P=0.013; year 2 aHR=1.67 [1.01-2.76], P=0.047). These associations were minimally changed by excluding outcomes within 1 year of the weight change. Deaths were from cardiovascular disease (35%), cancer (35%), infections (15%), and "other" causes (15%). Weight gain more than or equal to 20% in year 1 was associated with infection or "other" deaths, and weight loss more than 5% or weight gain more than or equal to 10% in year 2 with cardiovascular deaths. Conclusions. Significant posttransplant weight gain or loss was associated with poorer transplant outcomes. Reasons underlying these associations may differ between year 1 and year 2 weight changes.