Evaluation of national trends in the utilization of partial nephrectomy in relation to the publication of the American Urologic Association guidelines for the management of clinical T1 renal masses

Radical nephrectomy (RN) had been the standard of care for renal malignancy for nearly 4 decades [1]. However, increasing detection of small renal masses (SRM) has lead to a stage migration of renal masses [2, 3]. Smaller tumors suggest the opportunity perform more nephron sparing surgery; however, large national databases have suggested underutilization of PN [4‐7].

Increased knowledge of chronic cardiac and metabolic sequelae of RN, along with data suggesting oncologic equivalence for partial (PN) compared to radical nephrectomy for SRM, has prompted reconsideration of surgical approaches to renal masses [8‐14]. In 2009, the American Urological Association (AUA) published evidence-based practices guidelines for the management of clinical T1a renal masses as a guide for clinicians to consider PN to be the reference standard for T1a renal masses, and emphasizing the importance of renal preservation in patients with chronic kidney disease (CKD) [15].

To investigate the potential shorter-term impact of publication of the AUA T1 Renal Mass Guidelines, we analyzed the overall and rate of utilization of PN versus radical nephrectomy (RN) in a national cohort before and after the AUA Guideline release, with a focused analysis of utilization trends of PN in patients with non-dialysis dependent CKD.

We noted a 6.4% absolute increase in the proportion of PN in a two-year period performed before and after the guideline release; however, PN remains only about 35% of all nephrectomies performed. We used an adjusted multivariable analysis to identify a 23% increased odds of having a PN in the 2 years after Guidelines publication (Table 3). We were expecting to identify a rise in the rate of PN after Guideline publication, however there was no difference in incidence (Figure 1). While increase in PN utilization increase after AUA T1 Renal Mass guidelines publication was recently reported by Bjurlin et al. who noted a one year increase in PN proportion from 27% to 32% [18], our data are longer term and the conclusions we draw while seemingly similar (i.e., an overall increase). Nonetheless our results demonstrate that increase in PN utilization was more likely due to the overall steady rise in incidence over time rather than the AUA T1 Renal Mass Guidelines making a significant immediate impact (Figure 1). We describe increases in PN for high risk patients such as those with obesity, diabetes, and hypertension. Unfortunately, we noted no change in PN proportion with preoperative non-dialysis dependent CKD before and after the AUA T1 Renal Mass Guideline publication (Figure 2). While we are unable to target specific reasoning behind the lack of increase in partial nephrectomy among non-dialysis depended CKD patients, such as tumor factors, this finding is concerning considering it is highlighted as an imperative indication of PN in the Guidelines [15]. Moreover, the AUA guideline is similar to the EAU guidelines regarding treatment of renal mass with preference toward nephron sparing surgery (initially published in June, 2007 with update in 2010) [19, 20]. We highlight this finding as a potential quality of care issue which deserves further follow up.

Patients presenting with a renal mass and concurrent CKD are at highest risk of renal related morbidity and mortality [21‐23]. However, our study shows the United States continues to struggle to provide PN to patients because of social issues such as the patient’s financial means and where they reside, which agrees with reports from other reports from the NIS [24] and SEER Medicare data [24]. Recent health reform in American healthcare may change these trends and should be followed over time [25]. Despite current changes in healthcare, issues such as access to care, appropriate training, and hospital resources are also concerns for urologists. For example, urologists were criticized for poor adherence to guideline recommendations regarding a lower than anticipated use of intravesical chemotherapy for non-muscle invasive bladder cancer in population studies [26]. However when thoroughly investigated to improve care, the investigators found that the initial the baseline rates of non-adherence where actually justified [27]. The true reasons for not performing a PN also need to be studied in a similar fashion to the studies regarding non-muscle invasive bladder cancer, potentially a utilization of the newly developed American Urologic Association Quality Registry (AQUA).

Another potential reason for lack of increased adoption of PN for T1 renal neoplasms is that the seemingly overwhelming and robust retrospective data supporting PN has been called into question by publication of only prospective randomized randomized trial to address this topic, EORTC 30904, which was published in April 2011. This trial randomized 541 patients [PN (n = 268)/RN (n = 273)], with a median follow-up of 9.3 years, and noted that overall survival with a hazard ratio (HR) of 1.50, testing for non-inferiority was not significant (p = 0.77), and test for superiority was significant (p = 0.03) in favor for RN, though in RCC patients there were no significant differences with respect to overall survival. These findings were presented cautiously given shortcomings in study design and execution [13], however, they have already generated a great deal of controversy amongst thought leaders [18, 22, 23]. For the observation period and our analysis however, the impact of this study and its findings are likely limited and not noted. Indeed, longer observation is requisite to evaluate the impact of this study both on practice patterns in the United States, as well as in the formulation of updates to the AUA Guidelines document.

The criticism for PN utilization of only 35% in this population based cohort is tempered by the overall rise in incidence of PN in the past 4 years as well as the lack of evidence investigating physician clinical decision-making. We identified the largest improvement in PN performed based on hospital volume. In multivariable analysis, patients had a 2 fold increased odds chance of having a PN if the hospital performs at least 25 renal cases (partial or radical nephrectomies) per year confirming results of prior studies using the NIS [28]. Various reasons may account for this increase. Some reasons for the change in volume may include lower volume hospitals increasing number of PN performed, reflection of current referral patterns, and a combination of both. Additionally, PN in obese patients increased as which most likely is reflecting the increasing obesity epidemic in the United States, which is likely a welcome development given the fact that obesity is a driver for CKD as well [29].

We performed this study not to determine causality of the AUA T1 Renal Mass Guidelines on PN in the United States, but to identify potential opportunities for improvement. Creation of a guideline should only be the beginning of a continuous process of improvement as the ultimate success of depends on critical evaluation over time [30]. In general, guidelines are data driven documents that provide assistance to physicians and come after a majority of the physicians have already adopted the practice [31]. PN has been performed for more than a century, yet continued debate remains regarding its benefit and utilization [13, 32, 33]. The adoption of PN may be due in part to changes in technology such as laparoscopy and robotic surgery [4, 7]. Indeed our findings that the median hospital length of stay has decreased while there may be a rise in overall cost of procedure for PN, while likely indicative increasing adoption of minimally invasive partial nephrectomy (laparoscopic or robotic) our group has reported in previous studies [34, 35].

Limitations in the data derived from national databases are only as accurate as the codes that have been chosen for the patient. The NIS database does not have pathologic data and therefore may not solely focus on cT1a renal cortical masses. However, the NIS was chosen for its strength in the documentation of the procedure itself as well as the fact that up to 25% of small renal masses have benign histology, and would therefore not be documented in oncology driven databases [15]. Moreover, the pathology of the renal mass is usually not available to the surgeon prior to the decision for type of surgery, and we sought to examine trends in procedure utilization as opposed to oncologic outcomes. Though only 4 years are evaluated in our analysis, it is possible that tumor stage may have changed over time and could confound the analysis. We have provided extensive exclusion criteria to remove patients with advanced tumors from our analysis, which have been validated by our group and others in previous analyses [6, 20, 24]. Furthermore, CKD can be a generalized term and we did note variation within the CKD stages 2–5 codes. Nonetheless, the rate of CKD in patients undergoing RN or PN was 4.4% overall, which is similar in rate to the 4.3% prevalence of CKD Stage 1–4 reported in medicare patients and suggests that there is no coding bias favoring reporting of dialysis dependent CKD over CKD Stages 1–4. More specific and accurate determination and documentation of CKD are needed for patients presenting for PN for appropriate counseling.

Partial nephrectomy utilization has increased over the 4 years selected for evaluation and should be recognized. However, the lingering question is how many present with amenable tumors and/or various indications for partial nephrectomy and do not have the option offered. One such patient’s are those with CKD, in which a surgical decision could have significant impact on future health in which the urologists is not likely to serve the penalty. Therefore, a concerted effort should be placed on identifying patients who would most benefit from partial nephrectomy and providing that service despite demographic challenges. Additionally, further investigation regarding current clinical decision may provide more immediate problem solving opportunities.

We have identified a steady increase in PN over the four-year study period and more PN performed after the publication of the AUA Clinical T1 Renal Mass Treatment Guidelines. However, the rate of PN performed after the guidelines release was not faster indicating that other factors may be influencing the adoption of PN. Additional studies and longer-term follow up are needed to determine the practical effects and clinical significance of evidence-based guidelines.