kidney transplantation ( kt ) is one of the treatments widely used for patients with end - stage renal disease . kt is considered the best therapeutic method in patients with end - stage renal disease because of the increased life expectancy of the recipients . the factors known to influence the survival of the transplanted kidney in living kt patients are as follows : the donor 's age , the level of human leukocyte antigen ( hla ) histocompatibility , acute rejection , and the type of immunosuppressive drugs used [ 2 - 8 ] . however , with the improved surgical techniques and effective immunosuppression available today , conventional prognostic factors have taken on less significance . accordingly , the native renal function of the donor is thought to be more important . the most objective and universal index of renal function is the glomerular filtration rate ( gfr ) , which measures the amount of blood plasma filtered from the glomerulus in the unit of time ( ml / min ) . the gfr is measured by the creatinine clearance ( ccr ) from the urine collected for 24 hours . to the best of our knowledge , no study to date has investigated the relationship between the donor 's 24-hour urine ccr before kt and the recipient 's kidney graft survival ( kgs ) after surgery . therefore , on the basis of 10-year follow - up results after surgery , we tried to determine how the 24-hour urine ccr of the donor , measured before living kt , can influence the kgs of the recipient after surgery . this study was approved by the institutional review board of hallym university , chuncheon sacred heart hospital . a total of 71 patients who underwent living kt performed by single surgeon were recruited from a single institution from january 1998 to july 2000 . sixty - eight of the 71 recipients were retrospectively included in this study according to the following criteria : the donor 's 24-hour urine ccr was measured before kt , the patient was followed for more than 6 months , kgs was verified , and the patient did not undergo re - operation . the following parameters were recorded in each case : the donor 's age and gender , the recipient 's age and gender , blood relationship , the donor 's 24-hour urine ccr before kt , the recipient 's 24-hour urine ccr and kgs at follow - up , acute rejection , hla and hla - dr matching , and drugs used for immune suppression . the recipients with kidney graft loss or who were followed up for less than 6 months after kt were excluded from our study because their kgs was associated with increased perioperative morbidity or mortality . renal function was assessed by gfr by use of 24-hour urine ccr according to the formula : 24-hour urine ccr = urine creatininexurine volume / plasma creatinine . all values for 24-hour urine ccr were measured during hospitalization and were corrected on the basis of the body surface area to millimeter per minute per 1.73 m for exact and objective outcomes . acute rejection was confirmed through kidney biopsy in patients with clinical abnormalities , such as decreased urine output or serum creatine level increased by 25% or higher . kidney graft loss was defined as either ' dialysis in need ' or ' death associated with renal failure ' but not as ' death with a functioning graft . ' triple therapy was applied for immunosuppressive therapy , and cyclosporine was used as the main immunosuppressive drug . corticosteroid therapy was used in all recipients , and azathioprine and mycophenolate mofetil were used in 30 and 38 recipients , respectively . the cutoff value for donor 's 24-hour urine ccr was calculated by the minimum p - value approach and corrected by the bonferroni correction method . the kaplan - meier method was used to analyze kgs , and the log - rank test was used to compare the investigated groups . the prognostic values of parameters were evaluated by using both univariate and multivariate cox proportional hazards models . all p - values were two - sided , and p<0.05 was considered to be statistically significant . the recipients ' mean age was 36.8 years ( range , 20 to 59 years ) , and there were 37 males ( 54.4% ) . the most common primary cause of end - stage renal disease was glomerulonephritis ( 13 recipients , 19.1% ) . after kt , the mean duration of the follow - up period was 115.039.4 months ( range , 10 to 157 months ) . the mean 24-hour urine ccr levels of the surviving recipients , measured at 1 , 5 , and 10 years after kt , were 69.816.0 ( 67 recipients ) , 63.522.6 ( 60 recipients ) , and 59.934.2 ml / min/1.73 m the donors ' mean age was 35.9 years ( range , 21 to 58 years ) , and there were 42 males ( 61.8% ) . the mean 24-hour urine ccr level of the donors measured before kt was 122.821.2 ml / min/1.73 m. there were 21 cases of acute rejection ( 30.9% ) ( table 1 ) . during the follow - up period the mean kgs time of the recipients was 131.86.2 months , and the estimated 5-year and 10-year kgs rates were 88.2% and 61.0% , respectively . the optimal cutoff value for donor 's 24-hour urine ccr was 120.05 ml / min/1.73 m therefore , 120 ml / min/1.73 m was determined as the cutoff value . when the donor 's 24-hour urine ccr before kt was divided into less than 120 ml / min/1.73 m ( n=16 ) and greater than 120 ml / min/1.73 m ( n=52 ) , the mean kgs time of each group was 96.09.6 months and 139.56.8 months , respectively ( p=0.005 ) . the estimated 10-year kgs rate of each group was 39.0% and 67.2% , respectively ( fig . the results of the univariate analysis showed that the 24-hour urine ccr of the donor before kt was a significant risk factor of kidney graft loss ( p=0.001 , hazard ratio [ hr ] , 0.163 ) . in the multivariate analysis , the 24-hour urine ccr of the donor before kt remained an independent risk factor of kidney graft loss when corrected for all other variables ( p=0.005 , hr , 0.143 ) ( table 2 ) . kt is the best therapeutic method for patients with end - stage renal disease and has shown significant long - term outcomes . in about 800 cases of living kt investigated between 1991 and 2001 , foster et al . reported that the 5-year kgs rate ranged from 82.9 to 89.1% . using the united network for organ sharing registry , between 1998 to 2001 , cecka   analyzed 14,162 cases of living kt and reported that the 10-year kgs rate was 68% . in our study , between 1998 and 2000 , the recipient 's 5- and 10-year kgs rates of 88.2% and 61.0% , respectively , were similar to those reported in the previous studies . many studies have reported that the donor 's age , acute rejection , the level of hla antigen histocompatibility , and the type of immunosuppressive drugs are risk factors that influence the kgs rate [ 2 - 8 ] . however , with improved surgical technologies and the prevention of postoperative complications and the development of new immunosuppressive drugs , the kgs rate has increased from the late 1980s , and the conventional prognostic factors have taken on less significance . therefore , the native renal function of the donor is thought to be more important for the kgs rate after surgery . among the various indices of renal function , the most objective and universal index is the gfr , which is measured by the 24-hour urine ccr . the donor 's renal function , as measured by the serum creatinine , not ccr , was assessed in previous studies . to the best of our knowledge , this is the first study investigating the influence of the donor 's 24-hour urine ccr , measured before living kt , on the kgs rate after surgery . reported that the mean recipient 's 24-hour urine ccr level showed a 141.5% increase at 1 week after kt , although they did not assess the long - term renal function change . they stated that the residual function of the recipient 's native kidney function measured before kt did not show much correlation with the recipient 's renal function after kt . this means that the transplanted kidney function decides most of the recipient 's renal function after kt . therefore , we thought that one of the most important factors affecting kgs was the donor 's renal function measured before kt , as assessed by the 24-hour urine ccr . we considered the donor 's 24-hour urine ccr value of 120 ml / min/1.73 m as a division point . this was calculated by the minimum p - value approach compensated by the bonferroni correction method ( p<0.001 ) . when the donor 's 24-hour urine ccr level before living kt was divided into less than 120 ml / min/1.73 m and above this cutoff , the 10-year kgs rates for each group were 39.0% and 67.2% , respectively ( p=0.005 ) . the donor 's 24-hour urine ccr level before living kt was a significant prognostic factor in the univariate analysis ( p=0.001 ; hr , 0.163 ) and also in the multivariate analysis , which was corrected for all other variables ( p=0.005 ; hr , 0.143 ) ( table 2 ) . therefore , the donor 's 24-hour urine ccr must be measured before living kt and considered as a prognostic factor of kgs . kaplan et al .   reported that the donor 's age was a significant risk factor , i.e. , when the donor was older than 18 years , the kidney graft loss rate was increased . however , this result is in all likelihood due to a lesser functional reserve of the kidney , along with age - related injury , decreasing the kidney 's ability to withstand further damage . park et al .   reported that the donor 's age was not related to kgs in 57 months of follow - up after kt . blood relationship between donor and recipient was considered to be an important risk factor in the past , but not in recent studies . park et al .   reported that blood relationship was not a significant risk factor , and kaplan et al .   stated that the advantage of living donor kidneys held equally true for unrelated donors . blood relationship was not considered as a significant risk factor in our study , and we consider that transplanted kidneys with good renal function are more important than blood relationship . with the improved immunosuppression available today , hla matching has taken on less significance , although this is still considered to be an important prognostic factor . . however , it is difficult to determine its significance with statistic values only , because our result did not have a high confidence level . many studies have considered acute rejection as an important risk factor for kgs . in our study , the number of recipients with acute rejection differed between the two groups , although there was no statistical difference . it was thought that the difference in hla matching was one reason for this difference . in the multivariate analysis , it was also an important risk factor , and the kidney graft loss rate was 4.79 times higher when there was acute rejection . therefore , acute rejection is considered to be an important risk factor that determines kgs , together with the donor 's 24-hour urine ccr measured before kt . a few studies showed that different immunosuppressive drugs make a difference in the long - term outcome . both the short - term outcome and the acute rejection rate were improved , but the long - term outcome did not improve much . in our study , , several variables , such as newly developed immunosuppressive drugs or interleukin-2 antibody , which may better reflect clinical outcomes , were not included in the analyses . second , although our study continuously followed up on the recipients after kt , the 24-hour urine ccr was not measured on a regular basis for all recipients . however , our study included most of the conventional variables associated with kgs , and we studied recipients for 10 long years . third , other indices of renal function , such as the 24-hour albuminuria or more currently accepted iothalamic clearance test , need to be assessed . last , the number of cases in our study was relatively smaller than in previous studies , although we followed the patients for 10 years . despite these limitations , our study is significant as the first report on the influence of the donor 's 24-hour urine ccr measured before living kt , which is the most objective and universal index of renal function , on kgs . in the future , as surgical technology and immunosuppressive drugs are developed and the rates of kgs rise , the influence of the donor 's renal function on kgs will increase . the renal function of the donor measured before living kt , using the 24-hour urine ccr , was a significant prognostic factor influencing kgs . the objective renal function of the donor needs to be evaluated for living kt , and it should be considered before living kt .
purposewith the improved surgical techniques and immunosuppression available today , conventional prognostic factors have taken on less significance . accordingly 
 , the native renal function of the donor is thought to be more important . 
 thus , we analyzed the prognostic significance of the donor 's renal function as assessed by 24-hour urine creatinine clearance on kidney graft survival for 10 years after living kidney transplantation.materials and methodsfrom january 1998 to july 2000 , 71 living kidney transplantations were performed at a single institution . from among these 
 , 68 recipients were followed for more than 6 months and were included in the present analysis . 
 we analyzed kidney graft survival according to clinical parameters of the donor and the recipient.resultsmean follow - up duration of recipients after living kidney transplantation was 115.039.4 months ( range , 10 to 157 months ) , and 31 recipients ( 45.6% ) experienced kidney graft loss during this time period . 
 estimated mean kidney graft survival time was 131.86.2 months , and 5-year and 10-year kidney graft survival rates were estimated as 88.2% and 61.0% , respectively . 
 donor 's mean 24-hour urine creatinine clearance ( ccr ) before kidney transplantation was 122.821.2 ml / min/1.73 m2 ( range , 70.1 to 186.6 ml / min/1.73 m2 ) . 
 the 10-year kidney graft survival rates for cases stratified by a donor 's ccr lower and higher than 120 ml / min/1.73 m2 were 39.0% and 67.2% , respectively ( p=0.005 ) . 
 in univariate and multivariate analysis , donor 's ccr was retained as an independent prognostic factor of kidney graft survival ( p=0.001 and 0.005 , respectively).conclusionsdonor 's 24-hour urine ccr before living kidney transplantation was an independent prognostic factor of kidney graft survival . 
 therefore , it should be considered before living kidney transplantation .