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Prospective Long-Term Followup of Patients With Asymptomatic Lower Pole Caliceal Stones

Prospective Long-Term Followup of Patients With Asymptomatic Lower Pole Caliceal Stones
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  Prospective Long-Term Followup of PatientsWith Asymptomatic Lower Pole Caliceal Stones Kubilay Inci,* Ahmet Sahin, Ekrem Islamoglu, Murat T. Eren, Mehmet Bakkalogluand Haluk Ozen  From Faculty of Medicine, Department of Urology, Hacettepe University, Ankara, Turkey Purpose:  The intervention time of asymptomatic lower pole calculi remains controversial. In this prospective study weevaluated the natural history and progression rate of asymptomatic lower pole stones. Materials and Methods:  Patients were followed every 6 months. Computerized tomography in even years, ultrasound scanin odd years after initial visit and abdominal plain films between these visits were evaluated. The largest diameter wasmeasured for each calculus and the cumulative diameter was calculated for cases of multiple stones. Disease progression wasdefined as pain experienced during followup, stone growth or the need for intervention. Results:  A total of 24 patients, 14 male and 10 female, were followed for a mean of 52.3 months (range 24 to 72). Of the 24patients 3 had bilateral lower pole stones. Mean cumulative stone diameter at presentation was 8.8 mm (range 2.0 to 26.0).Progression in stone size was demonstrated in 9 of 27 renal units (33.3%) with 2 (11.1%) requiring intervention. There wasno need for intervention during the first 2 years of followup. Three stones passed spontaneously without any symptoms. Paindeveloped in 3 patients during followup, and 2 of them passed a stone and responded to the analgesics without furthertreatment. None of the patients had a pyelonephritic attack during followup. Conclusions:  Our results showed that observation could be considered for patients with asymptomatic lower pole stones.However, patients should be counseled about the 33% disease progression and 11% intervention rates.  Key Words: signs and symptoms, urinary calculi, observation I ncreasing stone size, localized obstruction, associatedinfection and acute or chronic pain are the indicationsfor treatment of lower caliceal stones. 1–3 Because thenatural history of small, nonobstructing asymptomaticlower pole calculi is poorly defined and the progression riskisnotclear,thereisstillnoconsensusonthetimingandtypeof intervention for these stones. Glowacki et al evaluated thenatural history of asymptomatic renal stones and reportedthat the risk of a symptomatic episode or need for interven-tion was approximately 10% per year, with a cumulative5-year event probability of 48.5%. 4 Recently in a retrospec-tive study 77% of asymptomatic patients with renal stonesexperienced disease progression with 26% requiring surgicalintervention. 5 The most appropriate management of lower pole calicealstones also remains controversial. ESWL® has low stone-free rates. 6–8 Flexible ureteroscopy is another treatmentoption with similar stone-free rates for lower pole calicealcalculi 1 cm or less. 9 Percutaneous nephrolithotomy has thehigheststoneclearanceratesbutismoreinvasive. 6,10 Inthisprospective study we evaluated the natural history and pro-gression rate of asymptomatic lower pole stones, and estab-lished a concept of the best management approach forasymptomatic lower pole stones. MATERIALS AND METHODS The study protocol was approved by the Hacettepe Univer-sity Human Ethics Committee. Any patient diagnosed withasymptomatic single or multiple lower pole caliceal stonesfor at least 6 months was eligible for inclusion. Patients witha history of treatment for renal stones with pyeloureteralsurgery, percutaneous renal surgery or ESWL were alsoincluded in the study if they remained symptom-free for atleast 6 months. Exclusion criteria were any coexistentstones in other pyelocaliceal locations, history of urinarytract congenital anomalies, solitary kidney, increased serumcreatinine (greater than 2 mg/dl), high grade hydronephro-sis, diabetes and pregnancy. Patients were informed aboutdiseases and treatment options in detail, and they wereactively involved in the decision making process.Baseline characteristics including patient age, sex, his-tory of urinary tract infection, number of previous stoneepisodes and most recent stone composition were recorded. All patients underwent a detailed evaluation including non-contrast spiral CT, excretory urography and urinalysis atinitial visit. Urine samples (24-hour) were collected on arandom dietary regimen to determine volume, oxalate, cal-cium, citrate, uric acid and creatinine. In the first 3 years allpatients underwent excretory urography as part of the im-aging protocol. However, this was extracted from the imag-ing protocol at the end of the 3 years. Patients were evalu-ated every 6 months. At each visit a history regarding thedevelopment of symptoms, urinary tract infection and he-maturia was taken, physical examination was performed, Submitted for publication October 19, 2006.Study received Hacettepe University Human Ethics Committeeapproval.* Correspondence:DepartmentofUrology,FacultyofMedicine,Hac-ettepe University, Sihhiye, Ankara 06100 Turkey (telephone:  90 3123051970; FAX:  90 312 3112262; e-mail: Vol. 177, 2189-2192, June 2007T HE  J OURNAL OF  U ROLOGY   ®   Printed in U.S.A. Copyright © 2007 by A  MERICAN  U ROLOGICAL  A  SSOCIATION  DOI:10.1016/j.juro.2007.01.154 2189  and serum creatinine, urinalysis and, when indicated, 24-hour urine samples were executed. CT in even years, ultra-sound in odd years after initial visit, and plain film of thekidneys, ureters and bladder between these visits were eval-uated. Additional CT evaluations were performed at therequested interventions. The largest diameter was mea-sured for each calculus, and the cumulative diameter calcu-lated was for multiple stones on standard axial and recon-structed coronal images. Stone sizes measured by CT at theinitial visit were compared with the sizes detected at inter- vention for the symptomatic patients, and at the last re-corded clinical visit for the remaining asymptomatic pa-tients.Disease progression was defined as pain experienced dur-ing followup, stone growth or need for intervention (intrac-table pain or pain causing impairment of quality of life,dilatation of the urinary system, recurrent urinary tractinfection and persistent gross hematuria). Student’s t testwas used for statistical analysis. RESULTS  A total 14 male and 10 female patients were included in thestudy. Patient age ranged from 22 to 73 years (mean 46.9).Ten patients had a history of urinary stone treatment(ESWL in 8, PCNL in 2). Of the 24 patients 3 had bilaterallower pole stones. Documented stone analysis was availablein 7 patients, revealing calcium oxalate in 6 and calciumphosphate in 1 stone. Based on the results of metabolicevaluations, dietary regimen and/or medical therapy wereadministered to 75% of patients.Patients were followed up for a mean of 52.3 months(range 24 to 72). A total of 83 CT examinations (7 patientshad 2, 12 had 3 and 5 had 4) were performed at 24-monthintervals. Three additional CT examinations were per-formed at months 30, 62 and 67 of followup. Mean followupfor CT was 47.6 months (range 24 to 72).Mean cumulative stone diameter at presentation was 8.8mm (range 2 to 26) (see table). Stone size at presentation measured as largest single diameter was less than 5 mm in29.6% (8 of 27), 5 to 10 mm in 44.4% (12 of 27) and 11 to 15mm in 25.9% (7 of 27). Overall increase in stone size was0.57 mm (p  0.459, 95% CI 1.00–2.15) at the end of 2-yearfollowup. Increase in stone size was demonstrated in 8 of 27renal units (29.6%). Mean increase in stone size was 4.43 mm(median 3.5, range 2 to 10) and mean increase in percentagewas 98.1 (median 54.7, range 17 to 350) in these 8 renalunits. However, none of these patients required interven-tion.Increase in stone size was 0.05 mm (p    0.971, 95% CI3.04–3.15) at the end of followup. In 9 of 27 renal units(33.3%) a mean of 7.2 mm (median 4.0, range 2 to 24) and a131.7% increase (median 54.7, range 25 to 400) was demon-strated (see table). Although the increase in stone size wasgreater in patients with a largest single diameter more than10 mm (42.9%) versus patients with a largest single diame-ter less than 5 mm (25.0%) and 5 to 10 mm (33.3%), the  Patient characteristics and stone activity at 24 months and end of followup PtNo.—Age—SexCumulative mmStone Size atPresentation(each stone size)24-Mo Followup End of FollowupCumulative mmStone Size(each stone size)Mm SizeDifference % ChangeCumulative mmStone Size(each stone size)Mm SizeDifference % Change1—60—M 8 8 0 0 10 2 252—33—F 2 9 (3, 3, 3) 7 350 9 (3, 3, 3) 7 3503—44—M 10 13 3 30 13 3 304—43—M 6 10 4 66.7 10 4 66.75—59—F 5 5 0 0 5 0 06—73—F 7 7 0 0 7 0 07—53—F 12 11   1   8.3 11   1   8.38—39—F:Lt 2 2 0 0 0   2   100Rt 2 2 0 0 0   2   1009—41—F 15 15 0 0 19 4 26.710—31—M 12 (7, 5) 10 (6, 4)   2   16.7 6.5   5.5   45.811—46—M 9 9 0 0 5   4   44.412—52—M 14 (8, 6) 18 (10, 8) 4 28.6 0   14   10013—37—F 7 10 3 42.9 9 2 28.614—48—M 15 15 0 0 14   1   6.715—61—M 13 13 0 0 13 0 016—22—F 4 4 0 0 0   4   10017—49—F 12 14 2 16.7 27 (15, 7, 5)* 15 12518—54—F 20 (12, 8) 17 (9, 8)   3   15 14†   6   3019—46—M:Lt 5 5 0 0 3   2   40Rt 3 6 2.5 83.3 0   3   10020—49—M:Lt 26 (7, 6, 4, 4, 3, 2) 12 (3, 3, 3, 3)   14   53.8 7   19   73.1Rt 3 3 0 0 7 4 133.321—49—M 6 16 10 166.7 30‡ 24 40022—50—M 4 4 0 0 4 0 023—30—M 12 12 0 0 12 0 024—56—M 4 4 0 0 4 0 0Mean 46.9 8.81 9.38 0.57 25.6 8.87 0.05 16.2* Patient required ESWL because of pain at month 30.† Patient required ureteroscopy because of obstructing ureteropelvic stone at month 62.‡ Patient required PCNL because of stone growth at month 67.  ASYMPTOMATIC LOWER POLE CALICEAL STONES2190  difference was insignificant. Three patients required ESWL,ureteroscopy and PCNL because of pain, an obstructing ureteropelvic stone, and stone growth at months 30, 62 and67 of followup, respectively. Three stones passed spontane-ously without any symptoms. Pain developed in 3 patientsduring followup, and 2 of them passed a stone and respondedto analgesics without further treatment. The spontaneouspassage rate was 50% for stones less than 5 mm in diameter,16% for stones 5 to 10 mm and 0% for stones larger than 10mm. Five renal units (18.5%) were stone-free at the end of followup. None of the patients had a pyelonephritic attackduring followup. DISCUSSION The intervention indications for renal caliceal stones areincreasing stone size, localized obstruction, associated infec-tion and acute and/or chronic pain. 1–3 Treatment indicationsfor renal lower pole caliceal stones are similar to those of other locations. However,nocomprehensibleconsensusontheappropriate time for management and type of intervention forsmall,nonobstructing,asymptomaticlowerpolecalicealstoneshas been constituted to date. Before the introduction of ESWL,small asymptomatic and minimally symptomatic calicealstones were managed expectantly to avoid the only alterna-tive therapy, open surgery. ESWL has been increasinglyused for the treatment of these stones to reduce the risk of complications and need for invasive procedures. The re-ported incidence of ESWL treatment of caliceal stonessmaller than 10 mm increased from 36% to 50% from 1986until recently in United States. 11–13  Although ESWL is considered a noninvasive treatmentoption for lower pole caliceal stones, the efficiency studied indifferent series is reported to be in a wide range. In ameta-analytic study conducted by Lingeman et al withESWL the stone-free rates ranged from 25% to 84.6% withan overall stone-free rate of 59.2%. 10 It has been suggestedthat stone clearance is affected by the collecting systemanatomy like lower infundibulopelvic angle or lower poleinfundibular width. 14–16 Furthermore, in a prospective ran-domized controlled trial with a 2.2-year clinical followup,Keeley et al reported no significant difference betweenESWL and observation when they compared asymptomaticcaliceal stones smaller than 15 mm in terms of stone-freerate, symptoms, requirement of additional treatment, qual-ity of life, renal function or hospital admission rate. 8 Following the technical improvements of flexible uretero-scopes and newer intracorporeal lithotriptors such as theholmium laser, ureteroscopic management has become analternative treatment option. Grasso and Ficazzola reporteda 94% stone-free rate and shorter operation time (less than1 hour) for lower pole caliceal stones less than 2 cm using retrograde ureteropyeloscopy. 17 However, more recentlyESWL and ureteroscopy for the treatment of small lowerpole stones (1 cm or less) were compared in a prospective,randomized, multicenter study. Radiographic evaluationwith CT in a 3-month followup revealed the stone-free ratefor ESWL and ureteroscopy to be 35% and 50%, respectively,with no statistical difference. 9  Although PCNL has hightherapeutic success rates independent of stone size, theinvasiveness and technically demanding nature limits usefor lower pole caliceal stones. 6,10 The natural history of asymptomatic lower pole stonesshould be defined to decide whether a prophylactic inter- vention is required. In a retrospective study Hubner andPorpaczy reported that infection developed in 68% of pa-tients with asymptomatic caliceal stones and 45% had anincrease in stone size in a 7.4-year followup. They suggestedthat 83% of caliceal calculi would require interventionwithin the first 5 years of diagnosis. 18 In addition, in acohort study Glowacki et al reported that in 107 patientsduring a 32-month followup a symptomatic event developedin 31.8% of patients with asymptomatic caliceal stones. 4 They also demonstrated that the cumulative 5-year proba-bility of a symptomatic event was 48.5%. Like Hubner andPorpaczy, those authors recommended prophylactic treatmentfor these stones to prevent renal colic, hematuria, infection orstone growth. In the latter study primary outcome eventswere defined as renal colic leading to stone passage,endoureteral removal, percutaneous and open surgery orESWL for symptomatic urolithiasis. On the contrary, in-creasing stone size and infection was not considered a symp-tom and no categorization for stone localization was men-tioned. Our study included specifically lower pole calicealstones and we observed that no patient required interven-tionina24-monthfollowup.Inaddition,anincreaseinstonesize without any need for intervention was detected in 8 of 27 renal units (29.6%). When we increased followup to 52.3months 9 (33.3%) patients had an increase in stone size.However, only 3 (11%) patients required intervention.In a retrospective study by Burgher et al asymptomaticstone natural history and risk of disease progression basedon the need for surgical intervention, development of pain orstone growth on serial imaging were evaluated in 300 malesubjects with a 3.36-year followup. 5 Overall 77% of patientshad disease progression and 26% required surgical interven-tion. In this study lower pole stones were grouped separatelyand 61% showed an increase in size. Although there was acumulative use of CT imaging during this study only 9% of patients underwent CT examination to determine the stonesize at initial visit. This does not explain the difference inthe stone growth rate versus our study (33%). On the otherhand our study is more accurate because all the stone sizecomparisons were conducted with CT evaluation from theinitial visit to the end. In addition, our results did not sup-port that small stones had a faster progression as mentionedin their study.In the study by Keeley et al in which observation iscompared with a noninvasive technique (ESWL) within a2.2-year followup, the stone-free rates were 17% and 28%,respectively, and revealed no significant difference. 8 Theobservation group stone-free rate was similar to our findings(18.5%). However, not only lower pole caliceal stones but allcaliceal stones were included in this study group, and one of the reasons for the relatively low 28% success rate of ESWLwas attributed to high lower pole stone rate (72%) in theESWL group. In their evaluation 21 patients in the obser- vation group (21%) required additional treatment (analge-sics, antibiotics or a procedure) and in our study 6 patients(22%) needed additional treatment (3 analgesics, 1 ESWL, 1ureteroscopy and 1 PCNL) in the 52.3-month followup. Inthe observation group 10 patients (10%) required invasiveinterventions (ureteroscopy in 6 and ureteral stent place-ment in 4) whereas the ESWL group had none. In our studynone of the patients required any intervention in 2 years and ASYMPTOMATIC LOWER POLE CALICEAL STONES 2191  only 2 renal units (7.4%) required an invasive procedure inthe 52.3-month followup.There are 2 weak points in our study. Our study groupconsists of a relatively small number of subjects due to a lackof patient compliance resulting from the stones being asymptomatic and a long followup (minimum 2 years). Inaddition, 75% of patients received medication during fol-lowup that could affect the natural history of the stones. Toevaluate the exact natural history of the stones patientsshould be observed without any medication or diet thatcould interfere with stone growth. However, specific fluidbased and dietary manipulations as well as drugs whenindicated are recommended to restore the abnormalities of urinary risk factors. 19 For ethical reasons none of the pa-tients with specific urinary abnormalities was followed with-out treatment. In other words, it would be considered un-ethical to withhold from patients in a research study aneffective treatment that they could obtain as part of theirroutine medical care. To our knowledge, despite these limi-tations our prospective study is distinctive for only evaluat-ing lower pole stones with a long-term followup using CT forevaluation. To date there are no published data particularlyabout patients with lower caliceal stones that differ fromother localizations in terms of treatment options. In addi-tion, our study has the longest prospective followup for thesekinds of stones in the literature. CT evaluation, a superiordiagnostic technique for small stones and accurate measure-ment of the stone size throughout the study, was a greatadvantage for evaluating stone growth without any skepti-cism. CONCLUSIONS Our study showed that a third of all patients with asymp-tomatic lower pole caliceal stones showed disease progres-sion and a third of the patients with disease progressionrequire intervention in the long term. Based on this finding we can suggest that asymptomatic lower pole stones can befollowed safely. However, patients should be counseledabout the 33% disease progression rate.  Abbreviations and Acronyms CT    computerized tomographyESWL    extracorporeal shock wave lithotripsyPCNL    percutaneous nephrolithotomy REFERENCES 1. Andersson L and Sylven M: Small renal caliceal calculi as acause of pain. J Urol 1983;  130:  752.2. Brandt B, Ostri P, Lange P and Kvist Kristensen J: Painfulcaliceal calculi. The treatment of small nonobstructing caliceal calculi in patients with symptoms. Scand J UrolNephrol 1993;  27:  75.3. Mee SL and Thuroff JW: Small caliceal stones: is extracorpo-real shock wave lithotripsy justified? J Urol 1988;  139:  908.4. Glowacki LS, Beecroft ML, Cook RJ, Pahl D and Churchill DN:The natural history of asymptomatic urolithiasis. J Urol1992;  147:  319.5. Burgher A, Beman M, Holtzman JL and Monga M: Progressionof nephrolithiasis: long-term outcomes with observation of asymptomatic calculi. J Endourol 2004;  18:  534.6. 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