At what average time do organ transplants typically get rejected?

From the Guidelines

Organ transplant rejection typically occurs in three main timeframes: hyperacute rejection within minutes to hours, acute rejection between one week and three months, and chronic rejection after three months. The most common cause of late graft dysfunction is chronic rejection, which presents at least 3 months following transplantation 1. Acute rejection, on the other hand, occurs from 1 week to 1 month after transplantation, with the best outcomes seen in patients receiving kidneys from living donors 1.

Key Timeframes for Rejection

• Hyperacute rejection: within minutes to hours after transplantation
• Acute rejection: between one week and three months post-transplant
• Chronic rejection: after three months, and can occur years later

The timing of rejection varies significantly based on factors including the type of organ transplanted, how well-matched the donor and recipient are, the patient's adherence to immunosuppressive medications, and individual immune responses 1. To prevent rejection, patients must follow lifelong immunosuppressive regimens, which can include medications such as tacrolimus or cyclosporine, mycophenolate mofetil, and corticosteroids like prednisone 1.

Importance of Monitoring

Regular monitoring through blood tests and sometimes biopsies is essential for early detection of rejection, as prompt intervention can often reverse the process and preserve organ function 1. Ultrasound (US) is the modality of choice to evaluate renal transplants early in the postoperative period, in the posttransplant period, and also for long-term follow-up 1. US is also used to guide diagnostic and therapeutic interventions, such as biopsy, nephrostomy placement, and fluid aspiration 1.

Reducing Rejection Risk

The introduction of calcineurin inhibitors (cyclosporine and tacrolimus) has dramatically reduced the rate of acute allograft rejection 1. However, these drugs are nephrotoxic at supratherapeutic levels, and toxicity is most common in the second or third month after transplantation, when the drugs are being titrated 1.

From the FDA Drug Label

The two primary efficacy endpoints were: (1) the proportion of patients who, after transplantation, had at least one endomyocardial biopsy-proven rejection with hemodynamic compromise, or were re-transplanted or died, within the first 6 months, and (2) the proportion of patients who died or were re-transplanted during the first 12 months following transplantation Biopsy-proven rejection with hemodynamic compromise at 6 monthsa 121 (38%) 120 (37%) 100 (35%) 92 (32%) Death or re-transplantation at 1 year 49 (15.2%) 42 (12.8%) 33 (11.4%) 18 (6.2%) Biopsy-proven, treated rejection at 6 months (includes death or re-transplantation) 137 (47.7%) 107 (38.5%) Death or re-transplantation at 1 year 42 (14.6%) 41 (14.7%)

The average time of organ transplant rejection is not explicitly stated in the provided drug labels. However, the labels do provide information on the rates of biopsy-proven rejection and death or re-transplantation at 6 months and 1 year after transplantation.

• Key findings:
  • Biopsy-proven rejection with hemodynamic compromise at 6 months: 32-38% of patients
  • Death or re-transplantation at 1 year: 6.2-15.2% of patients
  • Biopsy-proven, treated rejection at 6 months: 38.5-47.7% of patients
  • Death or re-transplantation at 1 year: 11.4-14.7% of patients Based on the provided data, it can be inferred that the majority of transplant rejections occur within the first 6 months after transplantation 2, 2.

From the Research

Organ Transplant Rejection Time

• The average time for organ transplants to get rejected varies depending on the type of organ and the individual's immune response.
• According to 3, lung transplant recipients are more frequently affected by acute rejection, especially during the first 6 months after transplantation.
• A study on liver transplantation 4 found that early acute rejection usually occurs within 28 days of transplantation, while later rejection is associated with a greater risk for progression to graft loss.
• Another study on liver transplantation 5 reported that episodes of cellular rejection usually occur within the first 2 weeks after liver transplantation, with an overall incidence varying from 50 to 100%.
• In renal transplantation, a study 6 found that the acute rejection rate at both 6 and 12 months was 19%, with two episodes beyond 12 months.
• The timing of rejection can also depend on various factors, including the immunosuppressive regimen used, age, race of recipient, and preservation injury 4.

Factors Influencing Rejection Time

• The type of organ transplanted: different organs have different rejection rates and timings, as seen in 3 for lung transplants and 4 for liver transplants.
• Immunosuppressive regimen: the use of certain immunosuppressive drugs, such as tacrolimus and mycophenolate mofetil, can influence the timing and incidence of rejection 3, 6.
• Individual factors: age, race, and underlying medical conditions can affect the risk and timing of rejection 4.

Average Rejection Time

• While there is no single average time for organ transplant rejection, most studies suggest that rejection is most likely to occur within the first few months after transplantation, with the highest risk period usually being within the first 6 months 3, 4, 5.