June 13, 2005
Increasing the Success of Liver Transplants by Managing Levels of Anti-rejection Drugs
Approximately 600 children receive liver transplants each year in the United States. The use of immunosuppressant drug therapy, namely calcineurin inhibitors (CNIs) such as cyclosporine and tacrolimus, has decreased the risk of liver rejection and increased patient survival rates. While these medications can aid positive outcomes, high levels of CNIs can cause seizures and kidney damage, and low levels increase the risk of rejection of the transplanted liver. A study in the June issue of The Journal of Pediatrics discusses an approach to managing the levels of CNIs to keep them within a safe range for each patient in order to minimize risks and maximize success.
John C. Bucuvalas, MD, and colleagues from Cincinnati Children's Hospital Medical Center and Intermountain Health Center employed a method of controlling the blood levels of CNIs to stay within target ranges for individual patients. The study involved 217 patients, aged 6 months to 21 years, who received liver transplantation at least three months before the start of the study.
In the past, doctors relied on their experience to make decisions about how and when to change CNI dosages. The method in this study used a four-step process of care that allows the dose to be changed only when the CNI blood levels fall outside certain ranges based on each patient's previous responses to dosage changes. A team of transplantation experts used a statistical process control methodology and a novel Web-based system to review each patient's CNI levels to determine potential toxicity, possible modification of the patient's target range due to post-transplant complications, excessive variation of immunosuppressant levels in the blood, and if the CNI levels were within an acceptable range for that particular patient. The team then used the data to determine if the patient's medication required adjustment to keep the levels within a safe range.
Initially, only 50% of CNI levels were within the acceptable target ranges; this increased to 80% after the process was implemented. The amount of variation in CNI levels was significantly reduced, and the method decreased the proportion of CNI levels in the toxic range from 10% to 5%, reducing the risk of negative effects.
The method used in this study, statistical process control, is relatively new to the healthcare industry. Although the management of CNI blood levels is important for liver transplant patients, Dr. Bucuvalas points out that "the essential observation of the current work is that managing variation can improve the quality of care." This method is currently being applied to liver transplantation, but it may also be used to decrease the risk in the care of patients with diabetes, seizure disorders, asthma, and hypertension.
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