Understanding Ureteral Access Sheath Use Within a Statewide Collaborative and Its Effect on Surgical and Clinical Outcomes

Introduction

Survey data estimate that 11% of Americans will experience a stone episode during their lifetime. ¹ Ureteroscopy (URS) is the most frequently performed surgical procedure to treat urinary stone disease (USD) in the United States. ² Ureteral access sheaths (UASs) facilitate repeated entry into the collecting system, with several potential benefits, including improved operative visibility, the ability to extract stone fragments, a diminished infection risk owing to decreased intrarenal pressures, and potentially increased longevity of reusable ureteroscopes. ^{3 –5} These benefits likely explain the widespread adoption of UAS use during URS. ^6,7

While there is little debate surrounding the benefits of UAS use, intraoperative insertion can result in unintended consequences with reported rates of significant ureteral injury in 13% of cases. ⁸ The late consequences of ureteral injury at the time of UAS placement are poorly defined. Although several small series, ^9,10 including one prospective trial, ¹¹ indicate that ureteral stricture rates are low following injury related to UAS placement, when a stricture does occur, this results in substantial morbidity for patients. ¹² Less is known regarding the impact of UAS use on patient outcomes, namely unplanned health care encounters, which occur in as many as 15% of patients following URS. ¹³

In this context, we evaluated the impact of UAS use on health services utilization following URS. In particular, we assessed the frequency and predictors of UAS use within a surgical collaborative in addition to defining the relationship between UAS use and unplanned health care utilization following URS for USD. This information will allow for improved patient counseling regarding UAS use and help guide surgical decision-making with the aim to improve the quality of stone surgery.

Methods

Results

We identified a total of 5316 primary URS cases conducted during the study period. UASs were used in 1969 (37.7%) of these cases. Patient characteristics differed with respect to UAS utilization (Table 1). UAS use was significantly more common in older patients, those with more substantial comorbidity (Charlson comorbidity index [CCI] ≥2) and BMI >30, and those with public insurance. Additionally, rates of UAS use were higher if the patient had a positive preoperative urine culture. Patients taking any alpha-blocker at the time of surgery had lower rates of UAS use.

Of the 22 practices included in this analysis, there was substantial variation in UAS use across practices (1.9%–96%, p < 0.05; Fig. 1). This variation in UAS use persisted regardless of stone location (Fig. 2). Access sheath use by ureteral and renal stone location is listed in Supplementary Tables S1 and S2, respectively. Regarding renal stones, we found that increasing stone size was directly correlated with increased likelihood of UAS use, p < 0.05 (Supplementary Table S3).

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FIG. 1.

Practice variation in the frequency of ureteral access sheath use during ureteroscopy. Color images are available online.

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FIG. 2.

Practice variation in the frequency of ureteral access sheath use by stone location. Color images are available online.

On multivariable analysis, controlling for practice variation, several factors increased the odds of UAS use, including increased comorbidity, male gender, increased stone size, renal stone location, presence of ureteral stent before URS, and ureteral dilation during URS (Table 2).

Unadjusted rates of ED visits (10.2% vs 8.0%, p < 0.05) and hospitalization (4.7% vs 3.3%, p < 0.05) differed between those patients in whom a UAS was and was not used, respectively. After controlling for patient- and practice-level differences, those in whom a UAS was used had increased odds of an ED visit (odds ratio [OR] = 1.50, 95% confidence interval [CI] 1.17–1.93, p < 0.05) and hospitalization (OR = 1.77, 95% CI 1.22–2.56, p < 0.05) relative to those without UAS use. Using this multivariable model, we did find that prestenting decreased the odds of an ED visit (adjusted OR = 0.68, 95% CI 0.52–0.88, p < 0.05). Stent placement at the time of surgery was not found to be significantly associated with ED visits (adjusted OR = 1.14, 95% CI 0.87–1.50, p = 0.3) (Table 3).

Regarding time to ED visit or hospitalization, ED visit rates differed between UAS and non-UAS groups. Median ED visit in patients with UASs was observed on postop day 3 (interquartile range [IQR] = 2–7) vs postop day 5 (IQR = 2–11), p < 0.05, for patients without UASs. Those whose surgery did not include UASs were hospitalized on median day 4 (IQR = 2–7) and those with UASs were hospitalized on postop day 5 (IQR = 2–9), p = 0.4041. The most common reasons for ED visits were pain (48%), followed by “other” (38.0%), and urinary tract infection/hematuria (21.5% each) (Supplementary Table S4). It is worth noting that some patients may have more than one reason recorded for the ED visit.

Postoperative imaging was available for 47.6% of patients to assess SFRs. Abdominal X-ray was the most common modality used (55.0% of patients), followed by US (21.9%) and CT (11.1%). On multivariable analysis, UAS use was associated with lower odds of being stone free (OR = 0.75, 95% CI 0.57–0.99, p < 0.05) relative to those where a UAS was not used.

Discussion

In this pragmatic evaluation of practice patterns within the state of Michigan, we report several interesting findings. First, access sheaths are commonly used (37.7% overall), with a surprising degree of variation in the frequency of UAS use depending upon the practice. Factors associated with UAS use included increased comorbidity, male gender, increased stone size, renal stone location, and presence of ureteral stent before URS, as well as ureteral dilation during URS. After controlling for risk factors, we found that UAS use increased the odds of unplanned health care utilization and decreased the likelihood of being stone free compared with cases where no UAS was used. Collectively, these findings suggest that UAS usage is not without risk to the patient and can potentially increase the burden on the health care system.

Using this multivariable model, we did find that prestenting decreased the odds of an ED visit when UASs were used (adjusted OR = 0.68, 95% CI 0.52–0.88, p < 0.05) (Table 3). Stent placement at the time of surgery was not found to be significantly associated with ED visits in UAS patients (adjusted OR = 1.14, 95% CI 0.87–1.50, p = 0.3) (Table 3); however, it must be taken into account that these two variables were covariates and not primary predictors. They were not the primary outcome of focus in this study, so conclusions drawn from this particular analysis must be interpreted carefully and necessitate further research.

We chose to exclude staged procedures from this particular analysis because they typically represent the highest risk and highest complexity patients. Often, staged procedures are for patients with large stones who may not be percutaneous nephrolithotomy (PCNL) candidates or have especially complex factors that preclude them from treatment in a single setting. There were a total of 303 staged procedures that were excluded, encompassing 5.4% of all URS procedures. This was a small proportion of overall cases and we felt it was worthwhile to exclude them as they could skew the results. Furthermore, we also chose to exclude centers with <10 cases. There were only 3 centers that treated <10 patients, and the number of patients treated at these three centers only added up to 10. We chose to exclude them to minimize variation due to low case volume or potential lack of proficiency. We felt that they may not be comparable with the rest of the group.

Previous investigators have shown that UAS use is frequent, in as many as two-thirds of URS procedures for renal stones. ⁷ International survey data indicate that 58% of urologists report UAS use in every URS case. ⁶ Interestingly, our data suggest a much lower frequency of UAS use across all stone locations. This likely exists because of our large variety of group practice types and settings. Prior studies have suggested using UASs in cases with concern for infection due to decreased intrarenal pressure ³ as well as in patients with coagulopathy or antiplatelet use because of decreased trauma from multiple passes of the ureteroscope. ¹⁴ In line with this, in our series, we found that patients with a prior positive urine culture and those on antiplatelet agents had higher rates of UAS use during their URS.

While up-front UAS use is suggested to improve visibility in addition to decreasing postoperative infection and bleeding risk, little is known regarding downstream consequences of UAS use such as unplanned health care encounters. Previous investigations into UAS use have focused on their association with SFRs and complications; however, ED visit rates and hospitalization rates after URS are not infrequent. Specifically, their association with UAS use has been poorly defined. In an administrative claims analysis of 93,523 procedures to treat USD, 15% of patients had either an unplanned ED visit or hospital admission within 30 days, resulting in an adjusted incremental expenditure of $23,436 per episode. ¹³ One of the novel findings from the current study was that UAS use was associated with increased odds of both an ED visit and hospitalization within 30 days of URS. Although questions have been raised if this is related to stent status, we found that even after controlling for this in our multivariable models, which used both preop stenting and stenting at the time of surgery as predictors, UAS use was still associated with increased odds of both ED visits and hospitalization. This highlights the importance of judicious usage of UASs; omitting UASs in select patients may help reduce the frequency of postoperative ED visits and, in turn, decrease the overall costs of stone surgery.

UASs have been proposed to enhance fragment removal, but results regarding their association with SFRs are inconsistent. Early retrospective data suggested a significant improvement in the SFR when a UAS was used. ¹⁵ However, more recent data from 2239 patients with renal stones treated with flexible URS found no difference in the SFR when a UAS was used, but there was an increased risk of complications. ⁷ It should be noted that significant variability in the definition of stone free between studies on the subject can preclude direct comparison. Nevertheless, recent meta-analysis data again suggest that UAS use does not improve the SFR, ¹⁶ consistent with our findings. Our study did not show better SFRs with UASs even after controlling for stone size, stone location, and other factors.

Our study does have several limitations. Although we capture a wide range of demographic, clinical, and operative data in the registry, our variable library is not exhaustive, thus the potential for unmeasured factors leading to confounding exists. The data set records numerous variables, but it does not have the granularity to look at every specific detail such as stent presence at the time of ED visit or hospitalization, although this may represent an area of future research. In addition, our overall rate of postoperative imaging is low, ¹⁷ so conclusions about the SFR must be drawn cautiously. That said, our rate of postoperative imaging is consistent with national claims-based data suggesting that imaging is performed in less than 50% of patients undergoing URS. As with any retrospective study, it is difficult to retroactively control for all variables through stats; the retrospective nature is an inherent limitation. Finally, we report data from a statewide clinical registry, thus our findings may not be generalizable to the broader urological community. However, the inclusion of a diverse group of academic centers as well as small and large private urology practices does mitigate this limitation to an extent.

Despite these limitations, this study is among the largest series to date to look at UAS use outcomes, which gives weight to the findings. Although UAS use is likely beneficial in patients at high risk for infection or in those with coagulopathy or taking anticoagulation or antiplatelet medications, our study indicates that the choice to use a UAS is not without potential consequences. Future work is needed to understand provider factors that may drive the variation in UAS use seen across the state. Potential next steps include leveraging the collaborative nature of MUSIC to define appropriateness criteria for UAS use.

Conclusions

UASs are employed in approximately one-third of URS procedures performed in the state of Michigan and we observed wide variation in use across participating urology practices. In our study, we found that UAS use was associated with increased odds of requiring a postoperative ED visit or hospitalization relative to patients in whom a UAS was not used. Based on these findings, future efforts are underway to understand appropriate use criteria for UASs in Michigan.