Urolithiasis DOI 10.1007/s00240-015-0783-3

ORIGINAL PAPER

Age‑related delay in urinary stone clearance in elderly patients with solitary proximal ureteral calculi treated by extracorporeal shock wave lithotripsy Osamu Ichiyanagi1 · Akira Nagaoka1 · Takuji Izumi2 · Yuko Kawamura2 · Tomoyuki Kato1 

Received: 29 January 2015 / Accepted: 6 May 2015 © Springer-Verlag Berlin Heidelberg 2015

Abstract  We investigated the effects of aging on the stone-free rate (SFR) after shock wave lithotripsy (SWL) for the treatment of proximal ureteral calculi. A total of 247 consecutive patients were retrospectively selected, classified into seven groups set at 10 year increments (from 20 to 90 years), and examined for SFR after SWL. According to our final analysis, 185 male and 62 female patients with an average age of 54.1 years had stones with a diameter of 11.5 mm and a density of 893.1 Hounsfield units. On average, SFR was 74.9 % at 3 months after 1.7 SWL sessions. SFR gradually reached ≥90 % for each age-group after 1.5–2 years. Median durations to achieve 50 % SFR were estimated to be 21 and 86 days for those in their 20 and 80 s, respectively. However, the difference between the two estimates was not significant (p = 0.064). The durations to achieve 50 % SFR for the other groups lay between these two estimates. Aging does not affect long-term SFR, but patients aged ≥80 years might experience delayed stone clearance within the first 12 months after SWL. Keywords  Aging · Extracorporeal shock wave lithotripsy · Ureteral stone · Stone-free · Elder

* Osamu Ichiyanagi [email protected]‑u.ac.jp 1

Department of Urology, Yamagata University Faculty of Medicine, Iida‑Nishi 2‑2‑2, Yamagata City, Yamagata Prefecture, Japan

2

Department of Urology, South Miyagi Medical Center, Aza‑nishi 38‑1, Ogawara Town, Miyagi Prefecture, Japan





Introduction Extracorporeal shock wave lithotripsy (SWL) continues to be a standard therapeutic modality for upper urinary stone diseases although endourological in situ lithotripsy techniques, such as flexible transurethral lithotripsy with holmium–YAG laser equipment, have taken on a central role in the treatment of urolithiasis. Many investigators have reported prognostic factors that affect stone-free rates (SFRs) after SWL, including stone size and position [1, 2], chemical composition [3], stone attenuation values on computed tomography (CT) [4], skin-to-stone distance (SSD) [5], renal pelvocaliceal anatomy of the collecting system [6], patient body mass index [7], and shockwave delivery frequency [8]. However, patient age has not been considered a predictive factor of SFR after SWL in case of upper urinary stones. Age has no relationship with SWL treatment outcomes in cases of ureteral stones, although a negative relationship exists between patient age and SFR in cases of kidney calculi after SWL therapy [5, 9–14]. Although the underlying mechanisms remain unknown, it is suggested that sclerotic changes in renal parenchyma occur with aging, leading to increased acoustic impedance and poor fragmentation, and consequently low SFR after SWL therapy for kidney calculi [9, 10, 15]. Previously, Ackermann et al. showed that patients aged >60 years had the lowest SFR for renal calculi among all age-groups [16]. While Abdel-Khalek et al. [13] reported that patients aged >40 years had a significantly lower SFR than younger individuals after SWL therapy for renal stones, they also suggested that patient age is not a significant factor in the treatment of ureteral stones [12]. In a large-scale research project by Ng et al. [10], 462 patients with solitary proximal ureteral stones who were categorized into three patient groups (≤40, 41–60, and

13

Urolithiasis

>60 years) had SFRs of 55.2, 47.5, and 41.1 % at 3 months after a single session of SWL, respectively. However, multivariate analysis showed no significant difference in SFRs for ureteral stones among the different age-groups. Recently, the same authors developed a clinically available and simple nomogram for predicting SFR at 3 months after a session of SWL for proximal ureteral calculi by postoperatively examining 94 patients aged 24–94 years [5]. Patient age was excluded from the nomogram as no significant contribution to SFR prediction was identified by multivariate logistic regression analysis, although the nomogram constituted three factors: stone volume, mean CT attenuation of stones, and SSD [5]. However, SFR at 3 months does not indicate a definite treatment outcome because the continuous passage of stone fragments occurs for up to 24 months after SWL therapy [17]. According to one study, residual stone fragments after SWL cleared spontaneously in 78.6 % of patients with a mean follow-up duration of 4.9 years [18]. In the present study, we aimed to investigate the influence of aging on long-term chronological changes in SFR following SWL treatment for proximal ureteral calculi.

collected from the medical records. The present study was approved by the ethical committee of South Miyagi Medical Center (an approval number; #14-02). Preoperative evaluation of urinary stones targeted with SWL Urinary stones were evaluated before SWL by plain abdominal X-ray imaging of the kidney, ureter, and bladder (KUB) and, if necessary, intravenous urography (IVU). In some patients, non-contrast helical CT at 120 kV, 200 mA, and 5 mm-collimation was performed with General Electric (GE) scanners (Light Speed Ultra, Hispeed NX/i, Discovery CT750HD, and Optima CT660, GE Medical Systems, Milwaukee, WI). Urinary stones targeted with SWL were evaluated for size and density by KUB and CT imaging, respectively, using Centricity PACS Web software (GE Medical Systems). Stone diameters were measured as the maximum longitudinal and transverse distances, and radiodensity was presented as Hounsfield unit (HU) attenuation values of stones. As reported previously [4], mean skin-tostone distance (SSD) was calculated as an average of distance from body surface to a targeted stone at 0°, 45°, and 90° as measured on CT.

Materials and methods SWL procedure and postoperative stone evaluation Collection of patient data We retrospectively examined medical archives containing data on 701 consecutive patients with proximal ureteral stones who underwent primary SWL using a Modulith SLXMX lithotripter at South Miyagi Medical Center between August 1, 2002 and August 1, 2013 (Ogawara Town, Miyagi Prefecture, Japan). The proximal ureter was defined as the section from the ureteropelvic junction to the upper margin of the pelvic bone, according to the European Association of Urology/American Urological Association guidelines [1]. In the present study, we included patients with a solitary proximal ureteral stone >5 mm in diameter. Exclusion criteria were as follows: horseshoe kidney, complete or incomplete double ureter, ureteral stenosis, cystine and uric acid stones, percutaneous nephrostomy and indwelling ureteral stent during SWL, and Eastern Cooperative Oncology Group performance status of 1 or greater [19]. In addition, patients who had undergone endourological or open surgery for urinary stones within 3 months after their final SWL session, and those not evaluated for stone clearance after a series of SWL sessions, were also excluded from the present study. Information on stone composition determined by infrared spectroscopy, medical expulsive therapy (MET) and the American Society of Anesthesiologists (ASA) physical status (PS) classification [20] as an indicator of perioperative general conditions of SWL-treated patients was also

13

According to the manufacturer’s instructions, SWL was performed with a gradual increase in shock wave energy at a frequency of 60, 90, or 120 shocks per min according to the operator’s preferences. SWL outcome was evaluated by KUB imaging after each session. A further session of SWL was performed if the previous session was unsuccessful. Stone-free status was defined as complete absence of stone fragments on KUB imaging after SWL. Unless it was possible to confirm whether small, calcified shadows were residual fragments on postoperative KUB imaging, noncontrast CT, IVU, or both were also performed to ensure correct evaluation. In the present study, stone-free status after a series of SWL sessions was used to indicate therapeutic success. An efficacy quotient (EQ) was calculated as reported previously [21] using the following formula:

 EQ = %stone free/(100 % + %retreatment  +%auxiliary procedures) × 100. Statistics Statistical tests performed using R statistical free software. p values

Age-related delay in urinary stone clearance in elderly patients with solitary proximal ureteral calculi treated by extracorporeal shock wave lithotripsy.

We investigated the effects of aging on the stone-free rate (SFR) after shock wave lithotripsy (SWL) for the treatment of proximal ureteral calculi. A...
876KB Sizes 0 Downloads 9 Views