Delayed Graft Function
Delayed graft function is a common complication after kidney transplantation where the newly transplanted kidney does not start working immediately, often requiring dialysis treatment in the first week after surgery.
Table of contents
- What is Delayed Graft Function?
- How Common is Delayed Graft Function?
- Why Does Delayed Graft Function Happen?
- How is Delayed Graft Function Diagnosed?
- How is Delayed Graft Function Treated?
- Duration of Delayed Graft Function and Its Impact
- Long-Term Outcomes
- Can Delayed Graft Function Be Prevented?
What is Delayed Graft Function?
Delayed graft function, often abbreviated as DGF, is a condition where a newly transplanted kidney does not begin working straight away after surgery. Instead of immediately filtering waste products from the blood, the kidney takes time to “wake up” and start functioning properly.[4]
The most common way doctors define DGF is when a patient needs at least one dialysis treatment (a procedure that artificially removes waste products from the blood) within the first seven days after their kidney transplant.[2][3] This definition is widely used because it provides a clear, practical way for transplant centers to identify and report the condition.
DGF is a form of acute kidney injury, which means sudden damage or reduced function of the kidney, but it is specific to the transplant process.[2] It’s important to understand that DGF represents a delay in kidney function, not a complete failure of the transplant.[4]
How Common is Delayed Graft Function?
Delayed graft function is quite common in kidney transplantation. Approximately one in three kidney transplants experiences DGF, with rates ranging between 25% and 30%.[3][4]
The frequency of DGF has actually increased over time. Between 1985 and 1992, the rate was about 14.7%, but this rose to 23% between 1998 and 2004.[2] By 2008, the rate had reached 21.3% of all kidney transplant patients in the United States.[2]
DGF occurs much more frequently when the donor kidney comes from a deceased donor, particularly when the donation happens after circulatory death (known as DCD, meaning donation after the donor’s heart has stopped beating).[4] The increase in DGF rates over time has occurred alongside the increased use of kidneys from expanded criteria donors and donation after cardiac death donors.[2]
Why Does Delayed Graft Function Happen?
Delayed graft function results from multiple factors that can affect the donated kidney. The main cause is ischemia-reperfusion injury, which is damage that occurs when blood supply to the kidney is cut off (ischemia) and then restored (reperfusion).[3][6]
Several factors related to the donor can contribute to DGF. These include how long the kidney was outside the body before transplantation (called cold ischemia time), the age and overall health of the donor, whether the donor required medications to support blood pressure, and whether the donor had conditions like high blood pressure or kidney problems.[3][5]
The type of donor also matters significantly. Kidneys from deceased donors are more likely to develop DGF than those from living donors because they experience more ischemia-reperfusion injury.[3] Donation after circulatory death carries a particularly high risk for DGF.[4]
Certain characteristics of the recipient can also increase the risk. These include being male, having a higher body mass index, and the length of time spent on dialysis before receiving the transplant.[5] Additionally, the immune and medical status of the recipient can play a role in whether DGF develops.[4]
How is Delayed Graft Function Diagnosed?
The most common way DGF is diagnosed is if a patient requires dialysis within the first seven days after their transplant.[4] However, doctors also monitor other signs that the kidney is taking time to begin working properly.
Medical teams closely watch creatinine levels (a waste product that healthy kidneys remove from the blood), urine output, and other indicators of kidney function.[4] These measurements help doctors understand whether the transplanted kidney is starting to function or if it needs more time to recover.
It’s worth noting that the definition based on dialysis use has some limitations. Sometimes dialysis may be performed for reasons other than kidney damage, such as managing high potassium levels in the blood or excess fluid, even when the kidney is beginning to function.[6]
How is Delayed Graft Function Treated?
DGF is managed primarily with supportive care while the kidney recovers. This approach focuses on helping the patient stay healthy while waiting for the transplanted kidney to start functioning.[4]
The main treatments include dialysis sessions to remove waste products from the blood, medications to control blood pressure and manage fluid levels in the body, and very close monitoring of kidney function.[4] Patients with DGF need careful management of their immunosuppression medications (drugs that prevent the body from rejecting the transplanted kidney).[8]
In most cases, the transplanted kidney gradually begins to work over a period of days to weeks.[4] During this time, patients may need to remain in the hospital longer than those whose transplanted kidneys function immediately, or they may be discharged to continue dialysis at their usual dialysis center while attending regular follow-up appointments at the transplant clinic.[8]
Duration of Delayed Graft Function and Its Impact
The length of time that DGF lasts can vary considerably among patients. In one large study, the typical duration was 10 days, and the vast majority of patients (95%) had resolution of DGF within 28 days.[5]
The duration of DGF appears to matter more than simply whether DGF occurs. Research has shown that DGF lasting less than 28 days does not significantly impact long-term kidney transplant survival.[5] However, when DGF extends beyond 28 days, it is associated with worse long-term outcomes for the transplanted kidney.[5]
Patients with DGF may experience longer hospital stays compared to those whose kidneys function immediately. Additionally, the rate of hospital readmissions increases as the duration of DGF increases.[5]
Long-Term Outcomes
The impact of DGF on long-term transplant outcomes has been the subject of considerable research, with some conflicting findings. Many studies have shown that DGF is associated with higher rejection rates and decreased long-term kidney survival.[2][3] DGF can translate to a 40% decrease in long-term graft survival compared to transplants without DGF.[2]
However, it’s important to understand that many kidneys affected by DGF go on to work well for years.[4] DGF represents a delay, not a failure of the transplant. The key factor appears to be how long the DGF lasts rather than just whether it occurs at all.
Research has shown that at the end of nearly 14 years of follow-up, DGF reduces the probability of having a functioning kidney transplant from 52% to 32%, increases the probability of being back on dialysis from 10% to 19%, and increases the probability of death from 38% to 50% compared to transplant recipients who do not experience DGF.[13]
Several factors may explain why some patients with DGF have worse long-term outcomes. These include problems with how the kidney tissue repairs itself after injury (called maladaptive repair), dysfunction of cellular structures called mitochondria that provide energy to cells, and a higher risk of acute rejection episodes.[3]
DGF is also associated with a higher risk of 30-day hospital readmission after the transplant.[8] This is why patients with DGF require close monitoring, careful management of medications that suppress the immune system, and prompt kidney biopsy (a procedure to examine kidney tissue) if DGF continues for an extended period.[8]
Can Delayed Graft Function Be Prevented?
Some strategies have been tested to reduce the risk of DGF, though success has been limited. Many different treatments aimed at preventing DGF have been evaluated in clinical trials, but most have shown minimal or no benefit.[6]
Two approaches have shown some promise. One study found that prolonged infusion of dopamine (a medication that affects blood flow) may help reduce DGF rates.[3] Additionally, using a machine to continuously pump cold preservation fluid through the kidney (called hypothermic machine perfusion) instead of simply storing it in cold fluid has been shown to decrease rates of DGF, although its effect on long-term kidney survival remains unknown.[6]
Some strategies during surgery and organ preservation can reduce the risk of DGF, but not all causes can be prevented.[4] Transplant teams work carefully to minimize risk wherever possible. Whenever feasible, receiving a transplant before starting dialysis (called preemptive transplant) from a living donor is preferred, as this approach is associated with lower rates of DGF.[3]
During and immediately after surgery, medical teams pay great attention to maintaining stable blood flow and blood pressure, and they avoid medications that can damage the kidneys.[3] These careful management practices help minimize the risk of DGF developing.
