Obese patients are less likely to be selected for kidney transplants. Given that excess weight may be protective in these patients, what should they and their physicians do?
Patients listed for transplants are usually on a waiting list for four to six years. Surgery is more challenging on patients who are obese, so they are asked to lose weight so the surgery can be done with fewer problems. But studies have shown that except for the technical surgical issues, the outcomes are similar. So it’s a dilemma and we don’t have any answer right now. We hope that we will have clearer answers in the future.
What roles might protein-energy malnutrition (PEM) and inflammation play in reverse epidemiology?
We believe that nutrition intervention is much more important than addressing traditional CVD risk factors in dialysis patients and others with chronic disease. In the future, I can see more attention being paid to nutritional interventions, including giving patients oral or IV nutritional supplements, and medication to improve appetite.
Appetite status is actually a strong predictor of survival in dialysis patients. One might even say that “those who go to McDonald’s and Jack in the Box live longer.” Going to such restaurants may be a surrogate for having a better appetite and better nutritional status.
Which foods and beverages do you think dialysis patients should consume and avoid?
Having a higher-than-average protein and calorie intake is important. But dialysis patients face other challenges. They must avoid high potassium and phosphorus intakes. To limit phosphorus, one must eliminate consumption of preservatives in sodas and from other non-protein sources. In other words, physicians should encourage dialysis patients to maintain a high protein intake, but to be sure this doesn’t lead to a high phosphorus and potassium intake. This is the dilemma.
If you had enough money for just one study on reverse epidemiology, what kinds of things would you choose to look at?
I would like to look at the effects of nutritional interventions on dialysis patients to better understand why weight gain is associated with better survival. I’d like to give some patients more protein and calories, and give them different types of nutrition and different types of medications to improve appetite and mitigate inflammation, and then see which groups of patients do better.
Do the principles of reverse epidemiology apply to patients who’ve had renal transplants?
No. Renal transplant patients exhibit a phenomenon called reversal of reverse epidemiology, which means they go back to normal. In transplant patients with successfully functioning kidneys, obesity becomes bad and is associated with worse, not better, survival. When you place a healthy organ in the patient, the entire model changes. You cure the disease and also cure the reverse association.