Patients who get a kidney transplant before dialysis usually do better overall than patients who are on dialysis who get a transplant. They live longer and the transplant itself lasts longer.
In addition, most measures of quality of life (such as not feeling fatigued, returning to work) are better with a transplant compared to being on dialysis.
Patients who opt for preemptive transplantation do not have to go through the risks associated with starting dialysis (placement of access fistula, graft or catheter). When a patient has to start dialysis, it is for his or her health.
But dialysis can, over months and years, be hard on the body, and people get worse bone disease and cardiovascular disease the longer they are on dialysis.
It is not clear why patients do better with a transplant before dialysis, but all the evidence suggests that a transplant before dialysis is associated with better outcomes for both you and your transplant function in the long run.