Introduction

Shock wave lithotripsy (SWL) and ureteroscopic lithotripsy (URSL) are well-established procedures for stone fragmentation; however, the morbidity, hospitalization, and lost work hours associated with these procedures can negatively affect the health-related quality of life (HRQoL) of the patients [1–3].

The choice of modality is based on the European Association of Urology (EAU) and/or American Urological Association (AUA) guidelines. Typically, SWL or URSL is recommended as the first-line treatment especially for kidney calculi <20 mm, proximal ureter calculi >10 mm, or distal ureter calculi <10 mm [4, 5]. However, selecting a modality is challenging, considering the advantages and drawbacks of both modalities. SWL, while minimally invasive, has an inferior stone-free rate compared with URSL; however, URSL requires anesthesia and longer hospitalization [6]. The need to select the therapeutic modality for urinary lithotripsy based not only on the stone-free rate but also on the subsequent HRQoL of the patient is increasingly recognized [7].

The concept of HRQoL is multidimensional, which includes psychosocial, physical, and emotional factors, as well as patient autonomy, and is applicable to a wide variety of medical conditions [8]. Patients with urolithiasis represent an ideal group for the investigation of HRQoL, considering the disease’s high prevalence, non-life-threatening nature, severe symptoms, and high recurrence rate [3]. However, only a few longitudinal studies have investigated HRQoL in patients undergoing lithotripsy for urinary calculi [9]. Several studies have evaluated HRQoL using the Short-Form 36-item survey (SF-36) [3, 9–12].

Hence, this study aims to compare longitudinal HRQoL between SWL and URSL at four timepoints: before surgery (Bef), on the day of discharge (0 mo), and 1 month (1 mo) and 6 months (6 mo) after surgical intervention, and to further investigate the factors that may significantly affect the HRQoL of these patients.

Patients and methods

Preoperative evaluation

In this institutional review board-approved study, we prospectively interviewed 377 consecutive patients who underwent lithotripsy (SWL, n = 97; URSL, n = 280) for the treatment of upper urinary tract calculi between June 2012 and January 2015 at Toyota Kosei Hospital. Patients eligible for inclusion were those who underwent SWL or URSL based on the EAU and AUA guidelines [4, 5] and who completed a minimum follow-up of 6 mo. We explained the advantages and drawbacks of both procedures to all patients, including the costs, hospital duration, success-free rates, and complications when providing the agreement documents, in order for them to fully participate in the decision-making process. After receiving the explanation, the patients selected the method they preferred. After the patients provided informed consent, their chosen procedure was performed. The exclusion criteria included the following: age <18 years, inability to understand or provide informed written consent, pregnancy, necessity to perform preoperative nephrostomy due to pyelonephritis or severe hydronephrosis, and an American Society of Anesthesiologists classification of physical status grade ≥3. A total of 262 patients (SWL, n = 61; URSL, n = 201) were included in the analysis. A flow chart of the study design is shown in Fig. 1.

Fig. 1
figure 1

Flow chart of the study design. This study was part of a broader investigation that measured the longitudinal HRQoL after lithotripsy. Of the 377 participants who underwent lithotripsy (SWL, n = 97; URSL, n = 280), 262 participated in the follow-up interview conducted 6 mo after surgery. SWL shock wave lithotripsy, URSL ureteroscopic lithotripsy, SD surgery day, SF-36 Short-Form 36-item survey, KUB (kidney, ureter, and bladder) plain abdominal radiography, US ultrasonography

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Preoperative imaging, including plain abdominal radiography, ultrasonography, and computed tomography, was performed to determine the location, size, and radiodensity of the stones as well as the degree of hydronephrosis. Size was defined as the longest diameter observed during the preoperative imaging investigations. The stone surface area was estimated using the formula described by Tiselius and Andersson (length × width × 3.14 × 0.25) [13]. Hydronephrosis was graded according to the Ellenbogen classification [14]. Patient characteristics and stone features are summarized in Table 1.

Table 1 Overview of the patient characteristics, operative parameters, and postoperative complications between patients undergoing SWL and those undergoing URSL
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As baseline assessment, all patients were administered the SF-36 [15, 16] (Japanese version 2.0) before surgery. The SF-36 is a 36-item survey covering eight dimensions: physical function (PF), role limitation due to physical health (RP), bodily pain (BP), general health perception (GH), vitality (VT), social function (SF), role limitation due to emotional problems (RE), and mental health (MH). These domains were scored from 0 (worst) to 100 (optimal). The scores were adjusted for comparison with a general population, with a score of 50 ± 10 points representing normal function. Moreover, three summary scores of the physical, mental, and role components (PCS, MCS, and RCS) derived from the eight domains were also obtained [16].

Treatments

SWL was performed using a Delta II® lithotripter (Dornier MedTech GmbH, Wessling, Germany). The patients received an analgesic agent (intravenous pentazocine) and were treated with up to 3000 shocks for renal stones, or 4,000 shocks for mid- and distal ureteral stones. The patients without complications were discharged the next day. URSL was performed under spinal (n = 89) or general anesthesia (n = 112) using a 200 or 365-μm Holmium YAG laser through a rigid or flexible ureteroscope (Flex X-2®, Karl Storz, Tuttlingen, Germany). A ureteral access sheath (12/14-Fr Flexor®, COOK Medical Inc., Bloomington, IN, USA, or 11/13-Fr Navigator®, Boston Scientific, Natick, MA, USA) was used also with a flexible ureteroscope.

Furthermore, a 6-Fr double-J stent with extraction strings and a 16-Fr urethral catheter were used in all patients after endoscopy and, if no complications had occurred, removed on postoperative day 2 using the extraction strings. The patients were discharged on postoperative day 3. We performed preprocedural urine cultures as part of the protocol and determined the need for antibiotic therapy based on the urine culture results. Patients with a negative urine culture result received cefazolin once before and after the procedure.

Postoperative evaluation

Plain abdominal radiography and ultrasonography were performed at postoperative month (POM) 1 and 3 in all patients to assess the stone burden. Stone-free status was defined as the absence of residual fragments measuring >4 mm in diameter. All patients were administered the SF-36 at a clinic at three timepoints to assess HRQoL: 0 mo, 1 mo, and 6 mo after lithotripsy.

The stone-free rate, hospital stay, operative complications, and analgesic requirements were compared between the SWL and URSL groups. Multiple linear regression analyses were applied to investigate the effect of various risk factors on the SF-36 scores of the three summary components at 0 M. Similarly, the relationships between postoperative pain for patients undergoing URSL (who had used analgesic agents >2×) and all other parameters were analyzed using a logistic regression model.

Statistical analysis

All data were analyzed using the SPSS statistical software version 22.0 (SPSS Inc., Chicago, IL, USA). Continuous data were recorded as means ± standard deviations and analyzed using the Student’s t test and Chi-square test. The longitudinal scores for each domain and the three summary scores were compared between the groups using analysis of variance. Logistic regression was used for the univariate and multivariate analyses. p values <0.05 were considered statistically significant.

Results

Surgical data

The stone-free rate at POM1 was significantly lower for SWL than that for URSL (62.2 vs. 89.1%, respectively; p < 0.0001). The stone-free rate at POM3 was increased compared with that at POM1 for both groups; however, the stone-free rate for SWL was still significantly lower than that for URSL (72.1 vs. 93.0%, respectively; p < 0.0001). The analgesic requirement after surgery due to postoperative pain was lower in the SWL group than in the URSL group (0.3 ± 0.08 vs. 0.9 ± 0.20, respectively; p < 0.001). Postoperative complications after SWL included subcutaneous hematoma (2/61; 3.3%) and subcapsular renal hematoma (1/61; 1.6%), and those after URSL included transient high-grade fever >38.5 °C (8/201; 4.0%), sepsis (3/201; 1.5%), treatment-resistant back pain (7/201; 3.5%), and liver dysfunction (1/201; 0.5%). The stone features and surgical data are summarized in Table 1. No significant differences between the SWL and URSL groups were observed.

SF-36

The longitudinal HRQoL data at Bef, 0 mo, 1 mo, and 6 mo for the SWL and URSL groups are summarized in Fig. 2. The scores in six domains (except for GH and VT) immediately after URSL were significantly lower compared with those before surgery. The patients after SWL had significantly lower scores in PF and RP. Patients who underwent URSL had significantly lower scores in PF, RP, SF, RE, and MH at 0 mo than those who underwent SWL. After URSL, the patients had significantly higher scores at 1 mo in RP, BP, SF, RE, and MH than at 0 mo and 6 mo in all domains. No differences in the mean scores for any of the domains at 1 mo and 6 mo between patients undergoing SWL and those undergoing URSL were noted. However, a significant longitudinal difference after SWL was observed for the BP subscale only. For the three summary scores derived from the eight domains, the URSL group had significantly lower scores at 0 M for the RCS subscale (Fig. 3).

Fig. 2
figure 2

Short-Form 36-item survey (SF-36) scores (y axes) at four timepoints for patients after shock wave lithotripsy (SWL) or ureteroscopic lithotripsy (URSL). The scores in six domains (except for GH and VT) immediately after URSL were significantly lower compared with those before surgery. The patients after SWL had significantly lower scores in PF and RP. Compared with SWL, URSL was associated with significantly lower scores at 0 month for 5 of the HRQoL domains: before surgery (Bef), month (mo), physical function (PF), role limitation due to physical health (RP), social function (SF), role limitation due to emotional problems (RE), and mental health (MH). *p < 0.05 vs. at the timepoint of before each surgery; ✝ p < 0.05 vs. URSL at 0 mon; # p < 0.05 vs. at the timepoint of 0 mo of each surgery. BP bodily pain, GH general health perception, VT vitality, PCS physical component score, MCS mental component score, RCS role component score

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Fig. 3
figure 3

Three summary scores of the physical, mental, and role components (PCS, MCS, and RCS, respectively) derived from the eight HRQoL domains. The URSL group had significantly lower scores at 0 mo for the RCS subscale

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Factors influencing the SF-36 summary scores

Results from the multiple linear regression analyses for the SF-36 summary scores (PCS, MCS, and RCS) at 0 mo are presented in Table 2. PCS was found to be negatively associated with age and analgesic requirements (β = − 0.174, p = 0.006 and β = −0.141, p = 0.034, respectively; R 2 = 0.073). MCS was found to be positively associated with age (β = 0.169, p = 0.008; R 2 = 0.071). Moreover, age and analgesic requirements were significantly associated with a lower RCS at 0 mo (β = − 0.137, p = 0.029 and β = −0.216, p = 0.002, respectively; R 2 = 0.0082).

Table 2 Multiple linear regression analyses of the influence of the risk factors on the Short-Form 36-item survey (SF-36) scores of the three summary scores at the day of discharge (0 mo)
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Predictors of postoperative pain after URSL

Results of the univariate and multivariate logistic regression analyses of postoperative pain after URSL are shown in Table 3. The univariate analysis identified the following variables to be significantly associated with analgesic agent use: age (p = 0.0006), sex (p = 0.0092), degree of hydronephrosis (p < 0.0022), and preoperative stenting (p < 0.0055). These variables were included in the multivariate analysis. Lower age, lower degree of hydronephrosis before operation, and absence of preoperative stenting were found to be independent predictors of postoperative pain.

Table 3 Univariate and multivariate logistic regression analyses of factors affecting the analgesic requirement (needed >2×) alter ureteroscopic lithotripsy
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Discussion

The annual incidence of upper urinary tract calculi has been steadily increasing in recent years [17, 18]. Consequently, urinary calculi have become one of the most common problems in urology clinics. Several techniques have been developed for urinary stone management, including SWL and URSL; hence, quantifying the clinical results of these different methods is of critical importance for this common non-life-threatening disease.

Here, HRQoL after URSL was found to be lower than that after SWL at 0 mo. Previous reports have also compared SWL with URSL regarding their influence on HRQoL [7, 11, 19, 20]; however, the results were inconsistent. Moreover, Arafa et al. reported that patients undergoing SWL had higher HRQoL for all eight domains compared with those undergoing URSL [7]. In contrast, such an advantage for SWL was not observed in a separate study by Mays et al. [20]. This discrepancy could be explained by differences in the timing of the SF-36 questionnaire administration. Furthermore, in the previous reports, the SF-36 questionnaire was administered inconsistently and at a single timepoint after an observation period ranging from 3 to 78 months [3, 9–11]. In our study, the SF-36 questionnaire was administered at four timepoints, and our data revealed that patients undergoing URSL had significantly lower scores at 0 mo in five of the eight HRQoL domains compared with those undergoing SWL. No differences in any domains at 1 mo and 6 mo between the patients were observed, and a superior HRQoL in patients undergoing SWL was observed only at discharge.

Among the three summary scores, the RCS was significantly lower in the URSL group than in the SWL group. Multiple linear regression analyses revealed that postoperative pain was one of the factors contributing to the low RCS after lithotripsy in patients undergoing URSL. Furthermore, in this study, the higher analgesic requirement appears to be another factor associated with the low HRQoL in URSL. In the URSL group, 81/201 patients (40.2%) required analgesia because of postoperative pain on the first postoperative day; the mean requirement was 0.9 ± 0.20 analgesic uses. Pain associated with urolithiasis is usually caused by acute distension of the renal capsule due to inflammation or hydronephrosis, in addition to the consequent ureteral smooth muscle spasms that occur as the ureter attempts to relieve the obstruction [21]. Moreover, long surgery time (>60 min), larger stone size, ureteral dilation, and use of a stone basket were suggested as risk factors for acute postoperative pain and complications [22, 23].

In this study, 6-Fr double-J stents and 16-Fr urethral catheters were routinely used in all patients after endoscopy and removed at postoperative day 2. Some studies have reported that ureteral stenting after uncomplicated ureteroscopic lithotripsy may be unnecessary as stents do not improve the stone-free rate and may increase urinary tract infection incidence, analgesic requirement, or late postoperative complications [24, 25]. However, another study reported that ureteral stenting is not a risk factor for acute postoperative pain, and the authors speculated that stent placement could prevent extreme pain as reflected by visual analogue pain scale scores >7 [23]. In our study, we suspect that the use of routine ureteral stenting may have been one possible cause of postoperative pain.

Moreover, we found that age, degree of preoperative hydronephrosis, and preoperative stenting were independent predictors of postoperative pain after URSL. Young patients (aged <60 years) required more analgesia than older patients, which is consistent with the findings of a previous study [26]. Patients who demonstrated severe hydronephrosis (grade >2) preoperatively, or who underwent stenting pre-URSL, required less analgesia. Hydronephrosis due to stone impaction and preoperative stenting can lead to passive dilation of the ureter and renal pelvis, which decreases the risk of acute distension of the renal capsule by irrigation during URSL. In addition, preoperative stent placement has also been associated with a decrease in surgery time and reoperation rates in patients with larger stone burdens [27]. Thus, stent placement prior to URSL may be a good choice for patients <60 years old or whose degree of hydronephrosis is grade <1 to improve the HRQoL.

In general, the immediate post-lithotripsy HRQoL was better in case of SWL than URSL. However, the stone-free rates of patients undergoing URSL were significantly higher than those of patients undergoing SWL in both POM1 and POM3; nevertheless, the overall stone-free rate for SWL (72.1%) in this study was comparable to those reported by other studies (57–97%) [4, 28]. Therefore, if the probability of ureteral stone disintegration is high in SWL, SWL should be the first choice of treatment, especially considering the relatively high HRQoL.

This study has certain limitations. First, the study was not randomized. The advantages and drawbacks of both procedures were explained to all patients to enable them to fully participate in the decision-making process. After the patients provided informed consent, their chosen procedure was performed. Second, we did not consider the patients’ stone history including the number or types of prior surgeries, and the number of prior stone events. Third, the number of cases included was relatively small, as some patients dropped out of the study before the final (6 mo) evaluation.

Conclusions

The post-lithotripsy HRQoL was significantly better for SWL than URSL on the discharge date, but not later. The longer hospital stay and greater postoperative pain appeared to be responsible for the lower HRQoL in URSL. The shorter hospital stay, less postoperative pain, and desire to be stone-free appeared to be responsible for the higher HRQoL in SWL, because SWL patients could not have known whether they would be stone-free later or not at the day of discharge. However, despite the lower stone-free rate of SWL, there were no significant differences in SF-36 scores between the groups at the 1- and 6-month timepoints. Control of unexpected stone events may not be the central issue in the daily lives of the patients because urolithiasis is not a life-threatening disease. For the appropriate decision regarding the treatment approach, it is important to understand not only the surgical outcomes and recurrence rates, but also the HRQoL associated with each treatment strategy. Because the higher postoperative pain immediately after lithotripsy appeared to be responsible for the lower HRQoL in patients undergoing URSL, placing a preoperative ureteral stent or preparing postoperative intravenous patient-controlled analgesia may improve the HRQoL in these patients.