Multi-length or 24 cm ureteric stent? A multicentre randomised comparison of stent-related symptoms using a validated questionnaire

Authors


Abstract

What's known on the subject? and What does the study add?

  • One of the suggested factors for stent-related symptoms is that excess distal intravesical stent mass may cause bladder irritation. There is a lack of studies investigating this in a randomised controlled fashion using a validated questionnaire.
  • This study compared two of the most commonly used length of stents (a 30 cm multi-length vs a 24 cm long stent) and showed no significance difference in stent-related symptoms in patients with either of these stents.

Objective

  • To investigate whether excessive redundant intravesical stent component contributes to the severity of stent-related symptoms in patients with a ureteric stent. We compared stent-related symptoms in patients who had either a standard 24 cm or multi-length ureteric stent.

Patients and Methods

  • In all, 162 patients with upper urinary tract calculi requiring ureteric stent insertion were randomised to receive either a 6 F × 24 cm ContourTM or multi-length 6 F × 22–30 cm Contour VLTM stent.
  • Patients were requested to complete the validated Bristol Ureteric Stent Symptom Questionnaire (USSQ) at 1 and 4 weeks after stent insertion and 4 weeks after removal.
  • The mean scores for each domain of the USSQ for both groups were compared using the Student's t-test.
  • Any adverse events, e.g. stent migration, early removal of stent due to stent-related symptoms and failure of stent insertion, were also recorded.

Results

  • In all, 153 patients who had successful stent insertion were requested to complete the USSQ and 74% of patients returned at least the week 1 questionnaire.
  • At 1 and 4 weeks with the stent in situ, comparison of the mean scores showed no significant difference in urinary symptoms, pain, general health, work performance, sexual dysfunction and number of days patients stayed in bed or reduced their routine activities.
  • Three (2%) patients had their stent removed early due to stent-related symptoms and five (3%) had failed stent insertion.

Conclusions

  • This study did not find any difference in symptoms between the 24 cm or multi-length Contour stents. However, the study was not powered to detect small differences particularly for the pain symptom domain.
  • Stents should only be used sparingly and the stent dwell-time should be minimised.
Abbreviation
USSQ

Ureteric Stent Symptom Questionnaire

Introduction

A ureteric stent is commonly used in both elective and emergency settings to drain the kidney. However, an indwelling ureteric stent is associated with significant pain and urinary symptoms in a high proportion of patients [1, 2]. The Ureteric Stent Symptom Questionnaire (USSQ) is a validated tool developed to assess the degree of stent-related symptoms [3]. Using this questionnaire, Joshi et al. [2] reported that symptoms from a ureteric stent had a negative impact on health-related quality of life in up to 80% of patients.

The cause of stent-related symptoms remains unclear. Thomas [4] reviewed the literature concerning stent symptoms and concluded that one of the main sources of symptoms was a long intravesical segment of stent. Since then, various studies have been conducted to determine the ideal length of stent for a patient based on anatomical parameters. Pilcher and Patel [5] found that patient's height is a better guide to determine the ideal stent length than direct ureteric measurement. A larger study based on a Chinese population also concluded that body height can predict the ideal stent length [6]. However, this remains debateable and two other studies did not agree with this conclusion [7, 8]. All these studies were based on intraoperative direct ureteric measurement or radiological review and did not include correlation with patient's symptoms.

Biometric formulae for ideal stent length are only relevant if stent length actually affects stent-related symptoms. As part of a two-phased study, we first set out to investigate whether increased intravesical stent mass would cause more stent-related symptoms. The present study compared stent-related symptoms between two commonly used lengths of stent, a 30 cm multi-length and a 24 cm long stent. If the study showed a significant difference, we would then proceed to compare patients with stent length calculated according to biometric formulae. A 24 cm stent length was chosen based on our experience that this is the length that fits most patients with a low risk of migration. Both stents were made from the same material and were of the same diameter.

Patients and Methods

In all, 162 patients were prospectively recruited from three urology centres in the UK (Norwich, Wakefield and Bristol). The included patients were aged 16–80 years with upper urinary tract calculi requiring ureteric stent insertion during the course of their calculi treatment. Exclusion criteria were as follow: patients with metallic stents or obstruction due to malignant pathology, pregnancy, bilateral or long-term stent insertion, >1.98 m tall, transplanted kidney or reconstructed urinary system, neurological disease affecting normal voiding, stent insertion after open or percutaneous renal procedures and inability to understand the questionnaire. The study was approved by the UK Multi-Centre Research Ethics Committee.

Patients were randomised to receive either a single length (6 F × 24 cm, ContourTM) or a multi-length stent (6 F × 22–30 cm, Contour VLTM) in a single-blinded way (unknown to patients). Randomisation by computer software (Microsoft Excel) was used in the operative theatre before stent insertion. All stent insertions were carried out with rigid cystoscopy, guidewire and fluoroscopy control.

All patients who had successful stent insertion were requested to complete the USSQ questionnaire at 1 and 4 weeks after stent insertion, and also at 4 weeks after stent removal, which served as the control. The questionnaire consisted of several domains including ‘urinary symptoms’, ‘pain’, ‘general health’, ‘work performance’ and ‘sexual matters’. Secondary outcome measures included adverse events, e.g. early stent removal due to stent-related symptoms, failure of stent insertion and stent migration.

The sample size was calculated based on previous results of the USSQ validation study [3]. A total of 128 patients, 64 per arm would be sufficient to detect a difference of 15%, 30% and 25% in the mean index scores for the urinary symptom, pain and general health domains respectively with 80% power.

Categorical data were analysed using the chi-square test. The mean scores for each main domain at week 1 and 4 after stent insertion, and 4 weeks after stent removal were compared using the two-tailed Student's t-test. All reported P-values were two-sided with statistical significance at 0.05.

Results

Of 153 patients who had successful ureteric stent insertion, 113 completed and returned at least the week 1 questionnaire (74%). There were 62 and 51 patients in 24 cm and multi-length groups, respectively (Fig. 1). The demographic data for both groups were comparable for age and sex (Table 1). The subsequent return rate for week 4 and the after stent removal questionnaires were 50% (n, 24 cm : multi-length 41:36) and 47% (n, 24 cm : multi-length 39:33), respectively. Comparing the mean scores for each main domain in the USSQ, there were no difference in ‘urinary symptoms’, ‘pain’, ‘general health’ and ‘work performance’ domains at 1 and 4 weeks after stent insertion, and 4 weeks after stent removal between the groups (Table 2). Although not statistically significant, there was a trend that patients in multi-length group reported more ‘urinary symptoms’ and ‘pain’ than the 24 cm group at 4 weeks after stent insertion (Fig. 2).

Figure 1.

Flow diagram of study.

Figure 2.

Graphical presentation of mean scores for each USSQ main domain.

Table 1. Demographic details
 24 cm groupMulti-length groupP
Number of patients6251 
Mean age (sd; median)52.3 (12.7; 54)50.6 (13.0; 49)0.47
Males : females51:1137:140.22
Table 2. Comparison of mean scores for each USSQ main domain
USSQ domainMean score (sd):
Week 1Week 4After stent removal
Urinary symptom   
24 cm group30.6 (8.1)28.7 (7.6)17.8 (4.8)
Multi-length group31.9 (8.2)31.2 (9.2)18.2 (7.4)
P0.420.190.61
Pain   
24 cm group23.4 (17.8)21.0 (16.3)4.7 (8.4)
Multi-length group22.8 (14.9)24.3 (17.1)6.0 (11.2)
P0.840.390.57
General health   
24 cm group14.3 (6.0)14.8 (6.0)9.7 (4.1)
Multi-length group15.1 (5.3)14.8 (6.0)9.9 (3.7)
P0.480.980.79
Work performance   
24 cm group7.1 (3.7)6.5 (3.7)4.1 (2.7)
Multi-length group6.9 (3.3)6.7 (3.1)4.6 (2.1)
P0.870.780.65

At 1 week after stent insertion, about eight out of ten patients in both 24 cm and multi-length groups had pain, haematuria and dysuria. A significant proportion of patients also had nocturia (Table 3). These symptoms were persistent at week 4 with the stent in situ, although the number of patients with dysuria and haematuria were reduced slightly in both groups. There was no significant difference in the incidence of pain between males and females (male : female 79% : 83% at week 1 and 81% : 79% at week 4). During the 4 weeks with the stent in situ, patients in the 24 cm and multi-length group spent an average of 2 and 2.5 days in bed, respectively (P = 0.65). Over the same period, patients in 24 cm and multi-length group had to reduce 7.4 and 6.2 half days of routine activities, respectively (P = 0.63). For sexual activity, 17% (six of 35) patients in 24 cm group and 9% (three of 34) in multi-length group were sexually inactive due to the symptoms associated with the ureteric stent (P = 0.32). Of those who were sexually active, there was no difference in the mean scores for sexual performance (P = 0.41).

Table 3. Number of patients with pain, haematuria, dysuria and nocturia
 24 cm group, n (%) Week 1 (n = 62) Week 4 (n = 41)Multi-length Group, n (%) Week 1 (n = 51) Week 4 (n = 36)P*
  1. *Chi-square test.
Pain   
Week 148 (77)42 (82)0.52
Week 431 (76)31 (86)0.25
Haematuria   
Week 150 (81)44 (86)0.42
Week 428 (68)23 (64)0.68
Dysuria   
Week 150 (81)41 (80)0.97
Week 426 (63)26 (72)0.41
Nocturia (≥2 times/night)   
Week 139 (63)27 (53)0.28
Week 423 (56)20 (56)0.96

Comparison of mean scores before and after stent removal showed significant reductions across all domains (P < 0.05) in both groups. In the present study, there were three (2%) patients who had their stent removed early due to severe stent-related symptoms (all from the 24 cm group) and five (3%) patients with failed stent insertion (two from the 24 cm group and three from multi-length group). There was no ureteric stent migration in this study.

Discussion

The high proportion of patients in the present study that had stent-related symptoms was comparable with other studies that used a similar symptom questionnaire [2, 9]. The present study did not show any significant difference in stent-related symptoms between a 24 cm and 30 cm multi-length stent despite a difference of 6 cm in length.

The main limitation of the present study is of the low response rate, with only 74% of patients returning at least the week 1 questionnaire. However, the non-return rate was similar in each group and multiple previous studies have also reported low response rates using similar questionnaires [2, 10, 11]. The present study was therefore only adequately powered (>80%) at week 1 to detect the differences set out initially for the ‘urinary symptoms’ and ‘general health’ domains. In addition, it was only powered to detect a difference of 45% in mean score for ‘pain’ rather than the 30% set out due to the high variability in pain score. Another limitation of the present study is that the indication for stenting was not fully characterised.

In our experience, a 24 cm long stent fits the vast majority of patients up to 1.98 m tall with a low risk of stent migration. This is further supported in that we did not have any patients with stent migration in the present study. Three patients from the 24 cm group had their stents removed early due to severe stent-related symptoms. Should these patients have completed the USSQ, this would most probably not have changed the outcome, as therewere slightly lower (although not significantly) mean domain scores in the 24 cm group for both ‘urinary symptoms’ and ‘pain’. Failed stent insertion rates were small and similar in both groups. All five failed stent insertions were due to tight ureteric orifices, requiring smaller 4.8 F stents to be inserted instead.

Stent length was reported as a significant factor for stent-related symptoms in a few previous studies. In a small non-randomised study, Ho et al. [12] compared patients with various stent lengths (22, 24 or 26 cm) and concluded that a longer stent causes more urinary irritative symptoms, but not flank or bladder pain. In another study, Al-Kandari et al. [13] randomised patients to either correct stent positioning or a longer incorrectly positioned stent (proximal end in upper calyx and distal end crossing the midline of the bladder). They showed that their flank pain score was not affected by the stent length but urinary symptoms were significantly worse in those who had a longer stent that crossed the midline of the bladder. Another recent smaller randomised study by Lee et al. [14] also concluded that proper stent position was more important than medication to relieve stent-related symptoms. However, the study was designed to compare the effect of α-blocker and anticholinergic medication on stent-related symptoms rather than for stent length or position. Their findings on α-blocker are different to several other studies [15]. All the three studies above were limited by the lack of validated questionnaire specific for ureteric stent symptoms.

The present study showed no significant association between excess intravesical stent component and stent-related symptoms. However, unlike other studies [12-14] we did not objectively assess whether the distal stent position crossed the midline of the bladder. This is because the length of ureter and position of ureteric stent vary with different body positions and urine volume in the bladder. A recent pilot study showed that the absolute vertical length of a ureteric stent varies with positions, longest in the supine position and shortest when sitting. Consequently, the position of distal stent coil also moved with every movement [16]. Therefore, a patient with a perfectly positioned stent on static X-ray could still have a distal stent coil that crosses the midline of the bladder when moving or sitting down. In a study to investigate risk predictors of morbidity in patients with ureteric stent, Giannarini et al. [17] identified that distal loop position crossing the midline of the bladder as a significant predictor. However, a post hoc analysis showed no significant correlation between stent length and distal loop position. Future stent designs may need to take in vivo dynamic movement of the ureteric stent into consideration.

In a well powered multicentre study using the USSQ, Lingeman et al. [18] tested the hypothesis that a reduced amount of stent material in the bladder would cause less stent-related symptoms by comparing different shaped stent. They compared two newly designed stents (distal pigtail end substituted with two ≤3 F loops that were either short or long) with two marketed stents. The study reported no significant difference in all the USSQ domains between the various stents. The present study supports their finding.

Even with continual development of various ureteric stent designs, we have to accept that many patients still have severe stent-related symptoms and there has not been consistent evidence that changing stent material, length, shape or thickness can reduce this. Pharmacological agents have shown more promise and recent studies reported that α-blockers seem to play a role in reducing stent-related symptoms [15].

In conclusion, this randomised comparison study did not show a significant difference in stent-related symptoms or health-related quality of life in patients who had either a multi-length or 24 cm Contour ureteric stent. However, the study was not powered to detect any small differences, particularly for the pain symptom domain. Stent-related morbidity was significant in each group and stents should only be used sparingly and the stent dwell-time should be minimised.

Acknowledgement

We would like to thank Eftychia Psarelli, statistician in medical statistics for her help in the study statistical analysis.

Conflict of Interest

Francis Keeley is a Consultant and Advisor for Boston Scientific.

Source of Funding

Funding provided by Boston Scientific.

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