Our survey-weighted sample yielded 35,370 bladder cancer subjects from the NIS who underwent radical cystectomy with urinary diversion in the years 1998–2005. Of those, 5,075 (14.3%) received a continent urinary diversion and 30,295 (85.7%) were reconstructed with an incontinent conduit. displays the characteristics of the study sample stratified by modality of urinary diversion. Subjects who received a continent reconstruction were younger than those who received a conduit. Continent diversion was more prevalent among males and less common among subjects with Medicare as the primary payer. Hospital characteristics associated with continent urinary diversion on univariate analysis included higher cystectomy volume, and urban teaching hospitals.
Characteristics of the study sample (weighted).
displays the multivariate model of covariates independently associated with continent reconstruction. Older age, female gender, having Medicaid or other insurance coverage, and select comorbid conditions were independently associated with decreased odds of continent diversion. Surprisingly, non-whites had higher odds of continent diversion than whites. Compared with subjects treated at urban teaching hospitals, those treated at urban non-teaching hospitals had lower odds of continent reconstruction following radical cystectomy for bladder cancer.
Multivariate logistic regression analysis of factors associated with continent urinary diversion.
displays trends in the proportion of continent diversions performed over time stratified by patient (panel A.) and hospital (panel B.) characteristics. The proportion of diversions that were continent rose sharply between 1998 and 2001. The highest increase was among subjects treated at hospitals in the 99th percentile of cystectomy volume. Thereafter, the proportion of continent diversions among all cystectomies performed plateaued, regardless of patient or hospital characteristics.
Time trend in the proportion of subjects undergoing continent diversion stratified by A) gender and B) hospital location and volume (HV: hospital volume).
To evaluate whether the trends identified reflected saturation of the highest volume centers, we examined rates of continent reconstruction at individual hospitals. Unweighted, our sample included 906 centers. Of these, no continent reconstructions were performed at 535 hospitals (59.1%) accounting for 1,500 of the 5,602 cystectomies in the unweighted sample (26.8%). At 218 hospitals (24.1%), greater than 25% of cystectomies were followed by continent urinary diversions, with surgical volume at these institutions ranging from 1 case over the study period to greater than 21 cystectomies annually. Over 40% of reconstructions were continent at 119 centers (13.1%), with hospital cystectomy volume ranging from 1 surgery over the study period to 10.2 cystectomies per year, on average. Mean cystectomy volume for centers performing more than 40% of diversions in a continent manner was 0.8, implying that the majority of centers performing a high proportion of continent reconstructions were low volume hospitals.
To determine whether differential utilization of continent diversion at high and low volume hospitals reflected differential case mix, i.e., identification of few high volume hospitals with high proportions of continent reconstructions implies that patients at these centers have a greater burden of comorbid illness, we examined rates of comorbid illness stratified by hospital volume (). We observed a trend toward increased comorbidity among subjects treated at low volume centers, which was significant for comorbid congestive heart failure, peripheral vascular disease, chronic lung disease, and iron deficiency anemia.
Prevalence of comorbid conditions stratified by hospital cystectomy volume.