1. Construct a population pharmacokinetic/pharmacodynamic model of tacrolimus in kidney transplant patients, and explore the quantitative relationship between combination drugs and gene polymorphisms on the safety and efficacy of tacrolimus in kidney transplant patients;
2. Based on the established pharmacokinetic/pharmacodynamic model of tacrolimus population in kidney transplant patients, combined with combined drugs, gene polymorphisms and other factors for simulation, predict the steady-state trough concentration and efficacy of tacrolimus in kidney transplant patients taking triple drugs (tacrolimus, mycophenolate mofetil/mycophenol sodium enteric-coated tablets, glucocorticoids), and apply the model to the real world to explore the optimal initial dose and maintenance therapeutic dose of tacrolimus, so as to achieve individualized and precise treatment and guide the rational clinical use of drugs.
3. Clarify the value of precision medicine guided by population pharmacokinetics/pharmacodynamics models in clinical practice.

This is a retrospective study. It is proposed to combine the classical basic principles of pharmacokinetics with mathematical statistical models, and use nonlinear mixed effect model (NONMEM) or other population pharmacokinetics/pharmacodynamics software to establish a population pharmacokinetic/pharmacodynamic model of tacrolimus in kidney transplant patients, and elucidate the combination of drugs, demographic factors, pathophysiological factors, genotype, The quantitative effect of comorbid diseases and drugs on the steady-state trough concentration and efficacy of tacrolimus in kidney transplant patients, so as to realize individualized and precise treatment of kidney transplant patients through model simulation and prediction of steady-state trough concentration and efficacy after taking drugs.

Inclusion Criteria:

• Patients undergoing kidney transplantation for the first time.
• Anti-rejection therapy with triple immunosuppressant (tacrolimus + mycophenolate mofetil + glucocorticoids).

Exclusion Criteria:

• The patient's medication status is unclear and there is a lack of relevant results of laboratory test indicators.
• The patient has undergone multi-organ or combined liver and kidney transplantation or has a history of liver and kidney transplantation.
• Transplantation failure or death.

All of the included population was kidney transplant patients,and all of they used triple immunosuppressant (tacrolimus + mycophenolate mofetil + glucocorticoids) for anti-rejection therapy,the results of laboratory could be collected.