while augmentation cystoplasty has seen its indications decrease with the advent of onabotulinum toxin a and neuromodulation , there remains a role for this procedure in the 21st century ( 1 ) .
analysis from the nationwide inpatient sample ( nis ) reveals that augmentation cystoplasty appears to be widely used in the surgical management of neurogenic bladder in patients with spina bifida ( 2 ) .
data from the pediatric health information system ( phis ) database demonstrates no change in augmentation rates between 1999 and 2004 , finding 665 patients who underwent augmentation cystoplasty over this 5-year period ( 3 ) . a recent study by uc san francisco demonstrated a decrease in the number of augmentations by 25% in the 2000s ( 4 ) .
institutional case series have examined complications of bladder reconstruction , suggesting it continues to have notable morbidity .
retrospectively analyzed 25 pediatric patients who underwent augmentation cystoplasty ( 5 ) and bladder substitution ( 6 ) between 1999 and 2007 , finding major complications including lower urinary tract calculi ( 39% ) , stricture or insufficiency of the continent vesicostomy ( 28% ) , and intestinal obstruction ( 9% ) ( 5 ) .
approximately one - third of patients who have undergone enterocystoplasty experience postoperative complications ( 6 , 7 ) .
these morbidities are secondary to a multitude of factors including surgical technique , inherent properties of the bowel segment , and patient compliance with maintenance regimens ( 8) .
we sought to determine , on a national scale , the readmission rates at 30 , 60 and 90 days after initial surgery , whether they have improved over the 7-year period , and to determine the influence of hospital and patient - specific variables with estimated costs of readmission .
this was a retrospective cohort analysis of the phis , a national administrative database containing combined hospitalization data from 43 tertiary care pediatric hospitals in the united states .
this study was reviewed and approved by the uc san diego human research protections program institutional review board ( irb ) with an informed consent waiver .
patients were followed across multiple hospital admissions to the same phis hospital using unique numerical patient identifiers .
patient privacy and confidentiality are protected and this study conforms to the ethical guidelines of the 1975 declaration of helsinki .
inpatient data , emergency room visits , observation , and ambulatory surgery / medicine visits are all included .
some hospitals contribute varying amounts of data , for example , only inpatient visits versus inpatient , ambulatory , emergency room , and observation visits .
each participating institution and an independent data management group review the data for accuracy each quarter .
data is only accepted into phis if classified errors occur in less than 2% of the quarterly data .
thirty - seven of the 43 hospitals had complete inpatient information during the study period and were included in the analysis .
we identified patients 0 - 17 years of age , from 2004 - 2010 , undergoing bladder reconstruction using icd-9 procedure codes : 56.51 ( formation cutaneous uretero - ileostomy ) , 57.87 ( reconstruction of urinary bladder ) , and 57.88 ( other anastomosis of bladder ) ; patients undergoing repair of bladder exstrophy ( icd9 57.86 ) were excluded .
descriptive statistics were used to characterize patient demographics , prevalence of surgeries , and readmission rates .
surgery prevalence was examined using linear regression and readmission rates were compared using the chi test .
total charges were compared between those who required readmission and those who did not , using the mann - whitney u - test .
costs are recorded in the phis database using a cost - to - charges ratio ( rcc - based ) for each hospital , which standardizes costs nationally taking into account variability in pricing and costs regionally .
although the rcc method is a good approximation for true costs , these costs are estimates and as such are only used in this analysis to compare between groups , rather than reporting them as a true exact cost amount .
ninety - day readmission rates were compared between hospitals after adjusting for hospital volume of augmentation surgery ( number of readmits / total number of augment surgeries ) .
gee ( generalized estimating equation ) regression was used to evaluate the influence of independent variables on 90-day readmission risk while adjusting for patient clustering within hospitals .
covariates entered into the original model included age , gender , race , insurance ( public / private ) , complex chronic condition ( which comprises a broad array of icd 9 codes for congenital anomalies ) ( 9 ) , length of stay ( < = 7 , > 7 days ) , year of surgery , days admitted prior to surgery to accommodate for bowel preps ( 0 or 1 ) and all 2-term interactions . only variables that remained significant in multivariate analysis remained in the final models .
significance for testing was set a priori at p < 0.05 , and stata ver .
this was a retrospective cohort analysis of the phis , a national administrative database containing combined hospitalization data from 43 tertiary care pediatric hospitals in the united states .
this study was reviewed and approved by the uc san diego human research protections program institutional review board ( irb ) with an informed consent waiver .
patients were followed across multiple hospital admissions to the same phis hospital using unique numerical patient identifiers .
patient privacy and confidentiality are protected and this study conforms to the ethical guidelines of the 1975 declaration of helsinki .
inpatient data , emergency room visits , observation , and ambulatory surgery / medicine visits are all included .
some hospitals contribute varying amounts of data , for example , only inpatient visits versus inpatient , ambulatory , emergency room , and observation visits .
each participating institution and an independent data management group review the data for accuracy each quarter .
data is only accepted into phis if classified errors occur in less than 2% of the quarterly data .
thirty - seven of the 43 hospitals had complete inpatient information during the study period and were included in the analysis .
we identified patients 0 - 17 years of age , from 2004 - 2010 , undergoing bladder reconstruction using icd-9 procedure codes : 56.51 ( formation cutaneous uretero - ileostomy ) , 57.87 ( reconstruction of urinary bladder ) , and 57.88 ( other anastomosis of bladder ) ; patients undergoing repair of bladder exstrophy ( icd9 57.86 ) were excluded .
descriptive statistics were used to characterize patient demographics , prevalence of surgeries , and readmission rates .
surgery prevalence was examined using linear regression and readmission rates were compared using the chi test .
total charges were compared between those who required readmission and those who did not , using the mann - whitney u - test .
costs are recorded in the phis database using a cost - to - charges ratio ( rcc - based ) for each hospital , which standardizes costs nationally taking into account variability in pricing and costs regionally .
although the rcc method is a good approximation for true costs , these costs are estimates and as such are only used in this analysis to compare between groups , rather than reporting them as a true exact cost amount .
ninety - day readmission rates were compared between hospitals after adjusting for hospital volume of augmentation surgery ( number of readmits / total number of augment surgeries ) .
gee ( generalized estimating equation ) regression was used to evaluate the influence of independent variables on 90-day readmission risk while adjusting for patient clustering within hospitals .
covariates entered into the original model included age , gender , race , insurance ( public / private ) , complex chronic condition ( which comprises a broad array of icd 9 codes for congenital anomalies ) ( 9 ) , length of stay ( < = 7 , > 7 days ) , year of surgery , days admitted prior to surgery to accommodate for bowel preps ( 0 or 1 ) and all 2-term interactions . only variables that remained significant in multivariate analysis remained in the final models .
significance for testing was set a priori at p < 0.05 , and stata ver .
, there has been no change in the prevalence of bladder reconstruction surgeries ( r : 0.191 ,  coefficient : -4.71 , 95% ci : -15.9 to 6.4 , p = 0.327 ; figure 1 ) .
there was no change in 30-day ( ranging from 14% to 20% p = 0.272 ) , 60-day ( 19% to 24% , p = 0.788 ) or 90-day readmission rates over time ( 23% to 27% , p = 0.924 ) ( table 2 ) . despite surgical volume adjustment ,
the majority of hospitals had similar 90-day readmission rates ( figure 2 ) . from a total of 37 hospitals ,
two had significantly higher readmission rates / volume and three had significantly lower readmission rates / volume than the mean .
the median cost for those patients requiring readmission was 1.76-fold higher than that of patients who were not readmitted based on rcc ( p < 0.001 ) .
2 hospitals had significantly higher readmission rate than the mean ( * ) , and 3 had significantly lower readmission rates ( ^ ) .
on multivariate analysis , a significant interaction was seen between gender and complex chronic condition ( ccc ) and as such , additional models were generated after splitting by gender : initial los > 7 days had 2-fold higher odds of readmission than < = 7 ( males or 1.647 , p = 0.001 ; females or 2.18 , p < 0.001 ) . within males ,
having a ccc was significantly associated with 90-day readmission ( or 1.898 , p = 0.001 ) ; ccc was not an independent predictor in females ( p = 0.147 ) .
between 2004 and 2010 , there was no significant change in the prevalence in bladder reconstruction in the pediatric population , nor was there any change in the rate of readmission of these post - surgical patients at 30 , 60 , or 90 days .
a recent study by schlomer et al . shows a 25% decrease in bladder augmentation over the last decade ( 4 ) .
however , the critical issue of this study is the need for early postoperative readmission , which has been stable and alarmingly high . beyond the direct morbidity to the patient
, there is also a tremendous cost to the health care system with a 1.7-fold increase over patients who are not readmitted .
the 90-day admission rate of 23 - 27% is comparable to the 30% readmission rate seen following either adult kidney or liver transplantation , which speaks to the severity of the condition and surgery ( 10 , 11 ) .
following urinary diversion in adults , the 90-day readmission rate has also been reported to be near 30% as well ( 12 ) . when counseling families and practitioners , the significant likelihood of readmission should not be underestimated .
single institutional studies have been able to identify long - term morbidity following reconstruction . in adults ,
welk et al . reported the rate of additional urological surgery after adult enterocystoplasty , finding 40% of patients required subsequent urological surgery in 243 patients , with a median follow up of 7.8 years ( 13 ) .
similar to adults , there is impressive morbidity after total bladder substitution in the pediatric population .
defoor et al . retrospectively analyzed a population of 26 patients , median age 8.9 years , with median
follow up of 8 years , who underwent neobladder creation , finding complications including reservoir stones ( 8 patients ) , febrile urinary tract infections ( 8 patients ) , metabolic acidosis ( 6 patients ) , small bowel obstruction ( 4 patients ) , bladder perforation ( 4 patients ) , and pelvic lymphocele ( 1 patient ) ( 14 ) .
although the short- to long - term complications following pediatric bladder augmentation / reconstruction have been enumerated , the likelihood of early readmission following initial surgery has not been studied from a population - based perspective . despite including 37 phis hospitals nationwide in our analysis with a diverse volume of bladder augmentation caseloads , our analysis found no appreciable difference in postoperative readmission rates among hospitals .
this could be secondary to several reasons , including the consistency of pediatric urologists at the majority of phis hospitals , the essential high morbidity of the surgery itself and its predisposing condition , or even the likelihood that an increased presence of patients with cccs at high volume centers may dilute the otherwise improved outcomes in the overall patient population .
there has been recent discussion within the adult genitourinary surgical community focusing on the regionalization of radical prostatectomy to high volume centers , secondary to the belief this would provide patients with improved outcomes . analysis compiled from the nis concluded that low volume institutions experienced inferior outcomes relative to the highest volume centers , irrespective of approach for radical prostatectomy , supposedly demonstrating the importance of accounting for hospital volume when examining the benefit of a surgical technique ( 15 ) .
however , in the present study cohort when adjusted for hospital volume , there is a similar readmission rate among all institutions . in 2011 , berry et al . used the phis database to characterize hospital readmissions between 2003 and 2008 , finding 21.8% of patients experienced at least 1 readmission within 365 days of a prior admission
; 2.9% experienced 4 or more readmissions within 365 days , accounting for 18.8% of overall admissions ( 16 ) .
of this 2.9% , 28.5% ( 2633 ) were re - hospitalized for a problem in the same organ system across all admissions during the interval . a retrospective analysis examined readmission among 1,083 patients hospitalized between 2006 and 2008 who were part of a structured , pediatric complex - care clinical program within 4 children s hospitals .
notably , almost half ( 47.1% ) of all complex - care clinical program patient admissions were related primarily to a surgical operation or major procedure ( 17 ) . in our analysis ,
multivariate regression found males with cccs were at increased risk of postoperative readmission ; this is supported by previous data which has already identified the use of cccs in models describing pediatric readmission rates ( 18 , 19 ) .
somewhat surprising was our finding that ccc was an independent predictor of readmission in males but not females .
this could be secondary to a yet unidentified gap in the care of male patients .
however , 83.5% of our cohort had a ccc , with 50% reporting a neuromuscular condition .
as a result , the attempted use of cccs for determining readmission risk is not ideal but was an attempt to find some way of quantifying risk .
we attempted to find other predictors of readmission including specific conditions such as obesity but only initial los > 7 days during the initial surgery yielded a 2-fold increase in likelihood of readmission .
rice - townsend et al . utilized a retrospective analysis of the phis database to identify disease severity among patients as the primary factor associated with readmission after treatment of appendicitis ( 20 ) .
this factor was highly variable across hospital populations and significantly altered ranking of performance - based outliers .
one of the limitations of our study is the inability to account for  disease severity  , going back to the lack of unified , descriptive data that is needed to better stratify and describe the cohort of pediatric patients undergoing bladder reconstruction .
additional limitations include a lack of readmission data in situations where pediatric patients were re - hospitalized in non - phis hospitals or patients were readmitted to a different phis hospital .
patients may have been readmitted for other reasons outside of the initial bladder reconstruction , thus overestimating our readmission rates .
the lack of sufficient finite data to characterize the reasons for readmission is a significant drawback in administrative databases , but we believe that a definite trend is seen in this study . the ability to generalize our results might also be limited to freestanding children s hospitals and does not represent the national norm , although it is estimated that 25% of children
s hospitalizations occur within children s hospitals ( national statistics on children , healthcare cost and utilization project , agency for healthcare research and quality , http://www.hcupnet.ahrq.gov/ ( accessed march 30 , 2013 ) .
children treated at children s hospitals have a higher prevalence of cccs than children at other hospitals , and this could potentially affect our results ( 21 ) .
in addition , our use of icd-9 coding to identify patients for inclusion is always subject to the quality of initial data collection and may unintentionally lead to inclusion of inappropriate or exclusion of appropriate patients . with health care reform initiatives looming , the future of medicine will likely include bundled payments for inpatient surgical and outpatient post - hospitalization care , ensuring accountability for patient outcomes and inpatient utilization among care providers ( 22 - 24 ) .
pediatric bladder reconstruction is a significant endeavor with an essential likelihood for future admission at substantial cost .
as evidenced in this study , readmission rates after pediatric bladder reconstruction have not improved over time .
single institutional studies have been able to identify long - term morbidity following reconstruction . in adults ,
welk et al . reported the rate of additional urological surgery after adult enterocystoplasty , finding 40% of patients required subsequent urological surgery in 243 patients , with a median follow up of 7.8 years ( 13 ) .
similar to adults , there is impressive morbidity after total bladder substitution in the pediatric population .
defoor et al . retrospectively analyzed a population of 26 patients , median age 8.9 years , with median
follow up of 8 years , who underwent neobladder creation , finding complications including reservoir stones ( 8 patients ) , febrile urinary tract infections ( 8 patients ) , metabolic acidosis ( 6 patients ) , small bowel obstruction ( 4 patients ) , bladder perforation ( 4 patients ) , and pelvic lymphocele ( 1 patient ) ( 14 ) .
although the short- to long - term complications following pediatric bladder augmentation / reconstruction have been enumerated , the likelihood of early readmission following initial surgery has not been studied from a population - based perspective . despite including 37 phis hospitals nationwide in our analysis with a diverse volume of bladder augmentation caseloads , our analysis found no appreciable difference in postoperative readmission rates among hospitals .
this could be secondary to several reasons , including the consistency of pediatric urologists at the majority of phis hospitals , the essential high morbidity of the surgery itself and its predisposing condition , or even the likelihood that an increased presence of patients with cccs at high volume centers may dilute the otherwise improved outcomes in the overall patient population .
there has been recent discussion within the adult genitourinary surgical community focusing on the regionalization of radical prostatectomy to high volume centers , secondary to the belief this would provide patients with improved outcomes . analysis compiled from the nis concluded that low volume institutions experienced inferior outcomes relative to the highest volume centers , irrespective of approach for radical prostatectomy , supposedly demonstrating the importance of accounting for hospital volume when examining the benefit of a surgical technique ( 15 ) .
however , in the present study cohort when adjusted for hospital volume , there is a similar readmission rate among all institutions .
in 2011 , berry et al . used the phis database to characterize hospital readmissions between 2003 and 2008 , finding 21.8% of patients experienced at least 1 readmission within 365 days of a prior admission ; 2.9% experienced 4 or more readmissions within 365 days , accounting for 18.8% of overall admissions ( 16 ) .
of this 2.9% , 28.5% ( 2633 ) were re - hospitalized for a problem in the same organ system across all admissions during the interval . a retrospective analysis examined readmission among 1,083 patients hospitalized between 2006 and 2008 who were part of a structured , pediatric complex - care clinical program within 4 children s hospitals .
notably , almost half ( 47.1% ) of all complex - care clinical program patient admissions were related primarily to a surgical operation or major procedure ( 17 ) . in our analysis ,
multivariate regression found males with cccs were at increased risk of postoperative readmission ; this is supported by previous data which has already identified the use of cccs in models describing pediatric readmission rates ( 18 , 19 ) .
somewhat surprising was our finding that ccc was an independent predictor of readmission in males but not females .
this could be secondary to a yet unidentified gap in the care of male patients .
however , 83.5% of our cohort had a ccc , with 50% reporting a neuromuscular condition .
as a result , the attempted use of cccs for determining readmission risk is not ideal but was an attempt to find some way of quantifying risk .
we attempted to find other predictors of readmission including specific conditions such as obesity but only initial los > 7 days during the initial surgery yielded a 2-fold increase in likelihood of readmission .
rice - townsend et al . utilized a retrospective analysis of the phis database to identify disease severity among patients as the primary factor associated with readmission after treatment of appendicitis ( 20 ) .
this factor was highly variable across hospital populations and significantly altered ranking of performance - based outliers .
one of the limitations of our study is the inability to account for  disease severity  , going back to the lack of unified , descriptive data that is needed to better stratify and describe the cohort of pediatric patients undergoing bladder reconstruction .
additional limitations include a lack of readmission data in situations where pediatric patients were re - hospitalized in non - phis hospitals or patients were readmitted to a different phis hospital
patients may have been readmitted for other reasons outside of the initial bladder reconstruction , thus overestimating our readmission rates .
the lack of sufficient finite data to characterize the reasons for readmission is a significant drawback in administrative databases , but we believe that a definite trend is seen in this study . the ability to generalize our results might also be limited to freestanding children s hospitals and does not represent the national norm , although it is estimated that 25% of children s hospitalizations occur within children s hospitals ( national statistics on children , healthcare cost and utilization project , agency for healthcare research and quality , http://www.hcupnet.ahrq.gov/ ( accessed march 30 , 2013 ) .
children treated at children s hospitals have a higher prevalence of cccs than children at other hospitals , and this could potentially affect our results ( 21 ) .
in addition , our use of icd-9 coding to identify patients for inclusion is always subject to the quality of initial data collection and may unintentionally lead to inclusion of inappropriate or exclusion of appropriate patients . with health care reform initiatives looming , the future of medicine will likely include bundled payments for inpatient surgical and outpatient post - hospitalization care , ensuring accountability for patient outcomes and inpatient utilization among care providers ( 22 - 24 ) .
pediatric bladder reconstruction is a significant endeavor with an essential likelihood for future admission at substantial cost . as evidenced in this study ,
 background : bladder reconstruction in the pediatric population is challenging for many reasons , including perioperative complications and readmissions.objectives:on a national scale , determine readmission rates at 30 , 60 and 90 days after bladder reconstruction in a pediatric population over a 7-year period , evaluating the influence of hospital and patient - specific variables.patients and methods : using the pediatric health information system database , we identified patients 0 - 17 years of age , from 2004 - 2010 , undergoing bladder reconstruction using icd-9 procedure codes . 
 descriptive statistics characterized demographics , prevalence of surgeries , and readmission rates . surgery prevalence over time was examined using linear regression . 
 readmission rates were compared using the chi2 test . 
 regression was used to evaluate the influence of variables on readmission risk.results:we identified 1,985 patients for inclusion , of which 52.7% were female . 
 median age was 9 years . 
 there has been no change in the prevalence of bladder reconstruction surgeries ( p = 0.327 ) . 
 there was no change in 30-day ( p = 0.272 ) , 60-day ( p = 0.788 ) or 90-day readmission rates ( p = 0.924 ) . despite surgical volume adjustment , 
 90-day readmission rates did not significantly vary among the majority of hospitals . 
 initial los > 7 days ( p < 0.001 ) and complex chronic condition males ( p < 
 0.001 ) were significantly associated with 90-day readmission.conclusions:no improvement in readmission rates after pediatric bladder reconstruction was observed during the study period . 
 nearly all centers have a similar readmission rate despite volume adjustment . 
1. Background
2. Objectives
3. Patients and Methods
3.1. Pediatric Health Information System
3.2. Data Collection and Analysis
4. Results
5. Discussion
5.1. Readmission Rates
5.2. Complex Chronic Conditions