In this retrospective cohort study, 451 KT recipients were followed up for 10 years. We developed a PMR score for these patients and found that almost 80% of the kidney recipients were classified as moderate to high risk of malnutrition. Malnutrition is highly prevalent in ESRD patients on hemodialysis treatment, and it is associated with hospitalization and death.29 However, data regarding the actual prevalence and incidence in transplant patients, especially during the first post-transplant year, and their relationship with graft and patient outcomes are underestimated. The immediate post-transplant period is considered the critical phase because the patient is recovering from the surgical procedure and taking high doses of immunosuppressant medications. The body needs to treat protein catabolism, promote wound healing, and treat electrolyte abnormalities. Malnutrition at this time is associated with impaired surgical wound healing and higher risk of infection. 30,31
About 85% of the patients from G1 received kidney from living donor compared with 46% and 36% of the patients from G2 and G3, respectively. Thus, patients from G1 had less time on hemodialysis and were transplanted younger than patients from G2 and G3, thereby reducing the risk of becoming malnourished. In addition, patients from G1 transplanted with a living donor had better HLA compatibility with their donors than patients from G1 and G3. Immunotherapy induction using rATG in malnourished patients from group 3 increased the incidence of post-transplant infections by cytomegalovirus, urinary tract infection, and polyomavirus.
Patients with higher risk of malnutrition in this study were associated with higher incidence of infections when the patient was induced with rATG. This treatment strategy is effective to reduce acute cellular rejection and possibibly humoral rejection in patients with immunological risk.32 However, it is associated with infectious complications. Malnutrition affects immunity, through a variety of mechanisms, increasing the risk of infection and infection itself contributes to malnutrition.33
In our study, we also found that patients with higher risk of malnutrition were associated with lower allograft survival. Our findings are consistent with previous studies. 34,35,36 Improving allograft function is essential to decrease the risk of graft failure and to enhance patient’s survival. The ability to predict short- and long-term outcomes in KT can be extremely useful for improving long-term results and for reducing the number of re-transplants.
Evaluation of the nutritional risk, one of the strongest predictors of morbidity and mortality in CKD patients, is a difficult and frequently forgotten process.37 Serum albumin, serum cholesterol level, and total lymphocyte counts are considered markers for nutrition status, and their low levels are associated with increased risk of mortality in ESRD.6,38,39 Hypoalbuminemia has been linked to poor clinical outcomes in all stages of CKD with higher hospitalization indices and mortality. Therefore, serum albumin is considered a reliable marker of nutritional and clinical status.13,40,41 Anthropometry may be used as a confirmatory tool; BMI is the most commonly used, and it is also a predictor for increased risk of mortality in patients undergoing regular dialysis.28,42 Extreme BMI values can be related to higher mortality of kidney recipients.43 Several nutritional scores have been developed over the years to help nephrologists, but none of them can be applied on every patient. Kalantar-Zadeh et al. developed the MIS for evaluation of the severity of malnutrition-inflammation complex syndrome on maintenance dialysis therapy.28 This system was already used to evaluate malnutrition in different stages of CKD and showed an association with mortality in those patients, including KT patients.35,40 However, the regular assessment of complete clinical parameters is time consuming, it can be expensive and not practical in the routine pretransplant evaluation. Therefore, the use of a simple nutrition screening can be very helpful. A tool that can also be used without a nutrition expert evaluation, such as anthropometric, laboratory, and clinical data are already available in the patients' medical records. .In our experience, this study appears to be the first to evaluate the predictive power of poor nutritional status on graft and patient outcomes by using a simple score based on routine objective measurements.
This study has several strengths, including its design and the relatively notable size of kidney transplant patients with 10 years of follow up. Our study has some limitations. It is a single center study. Information bias could not be dismissed, as the data were obtained from medical records. Despite this, the sample size was adequate and a robust statistical analysis was applied in order to give this study external validity and reproducibility. This study has the potential to be of great importance and application for the pretransplant evaluation of recipients.
In conclusion, patients with higher malnutrition risk score were associated with worse outcomes and poor allograft survival. This study highlights the importance of nutrition screening to identify malnutrition as early as possible in pretransplant patients. Predicting short-term outcomes in KT can be useful to foresee long-term results and reduce the need for retransplantation. Future studies are necessary to better elucidate the metabolic changes and special nutrient demands in this period and to further explore the benefits of nutrition intervention on pre- and post-transplant outcomes.