Risk factors associated with weight gain after kidney transplantation: A cohort study

BACKGROUND: Renal transplantation is the best modality of renal replacement therapy for patients with end-stage renal disease. However, it is associated with weight gain and metabolic abnormalities, which adversely impact transplant outcomes. OBJECTIVE: The objective of this study was to identify the risk factors of one-year weight gain after renal transplantation. METHODS: A retrospective cohort study was conducted with 374 patients that underwent kidney transplantation between January 2006 and July 2013. Clinical and laboratory variables were collected from electronic records, and the outcome of interest was weight gain during the first year after renal transplantation. The data were reported as mean ± standard deviation, median (interquartile range) or number of subjects (%). The association between variables were assessed via chi-square test and ANOVA. For analysis of risk factors related to the outcomes of interest, multivariable logistic regression models were used. RESULTS: There were 181 (48.4%) female patients, 334 (89.3%) with white ethnicity and the mean age was 44.4 ± 12.8 years. The mean BMI pre-transplant was 24.7 ± 4.1 kg/m(2), and 35 (9.9%) patients were classified as obese; 119 (33.6%) as overweight; 187 (52.8%) as normal weight; and 13 (3.7%) as malnourished. After one year of follow-up, the mean BMI was 26.2 ± 5.0 kg/m(2), and 61 (17.3%) patients were classified as obese; 133 (37.8%) as overweight; 148 (42.0%) as normal weight; and 10 (2.8%) as malnourished. Weight gain was observed in 72.7% patients, and the average increase was 7.12 ± 5.9 kg. The female gender, lower pre-transplant body weight, lower number of hospitalizations, and a kidney received from a living donor were associated with weight gain by more than 5% in the first year post-transplant. CONCLUSION: Female gender and lower pre-transplant body weight were independently associated with weight gain by more than 5% in the first year after kidney transplantation; lower rates of hospitalization and donation from living donors were also risk factors for this outcome.