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EDITORIAL COMMENT

Albala et al present a prospective randomized multicenter trial com-paring shock wave lithotripsy to percutaneous nephrolithotomy formanagement of stones up to 3 cm. in length isolated to the lower polecollecting system. The authors conclude that shock wave lithotripsy is areasonable first line therapy only for stones less than 1 cm. in length butfor those larger than that percutaneous nephrolithotomy is preferabledue to the “high degree of efficacy and acceptably low morbidity.” As

this study is prospective and randomized, the objective results can beaccepted as presented. However, the Conclusions and recommendationscan and should be open to one’s own interpretation.

It is surprising that these authors would use only a single dimensionto measure and categorize stone size, especially as the correspondingauthor was among the first investigators to suggest and support the useof stone surface area for all such research, presentations and publica-tions (J Urol, 148: 1026, 1992; J Urol, 147: 1219, 1992). As a result, fromthis study the authors would recommend treatment of a 0.9 � 0.9 cm.(0.81 cm.2) calculus with shock wave lithotripsy but in contrast, recom-mend that a 1.2 � 0.5 cm. (0.6 cm.2) calculus be treated primarily withpercutaneous nephrolithotomy. The reader may have difficulty recon-ciling this recommendation.

The definition of “success” of treatment in this study is still unclear.Obviously, if only stone-free rates are used, percutaneous nephrolitho-tomy will ultimately prove superior. However, there are many patientswith symptomatic calculi at the outset who become asymptomatic aftershock wave lithotripsy and in fact have minimal residual “dust” thatmay be seen on nephrotomography. Surely, most such patients as wellas the treating urologists consider the treatment successful and in fact,the quality of life data reported here clearly confirm that. Moreover, itwould be interesting to see the quality of life data stratified by stonesize, especially for the controversial 1 to 2 cm. group.

The reader may also harbor concern regarding the frequency andseverity of complications in those patients treated with shock wavelithotripsy versus percutaneous nephrolithotomy. Although the au-thors found no statistically significant difference in the frequency ofcomplications, which in fact occurred twice as often in the percuta-neous nephrolithotomy group, the lists hardly appear comparable. Isuspect most urologists would opt for the shock wave lithotripsygroup, from which one may fail to discern a single significant com-plication compared to the percutaneous nephrolithotomy group withthe sepsis, perforations, transfusions and anteriovenous fistulas.

We are grateful to have this published data from a prospectiverandomized trial performed by highly regarded investigators andclinicians. However, we should all retain the right to interpret thedata ourselves and form our own conclusions. Personally, I agreethat with few exceptions, stones in the lower pole or anywhere else inthe pyelocaliceal system less than 1 cm. can and should be treatedprimarily with shock wave lithotripsy, while those greater than 2 cm.should generally be treated with percutaneous nephrolithotomy.However, it has been our practice that for patients with stonesbetween those parameters shock wave lithotripsy can generally beperformed successfully, although many factors must be considered torecommend the most appropriate management. These factors in-clude but are not limited to presumed stone composition and fragil-ity, concomitant medical problems, body habitus, pyelocaliceal anat-omy, and overall and ipsilateral renal function. Our interpretation ofthe data presented here has served only to reinforce that protocol.

Stevan B. StreemDepartment of UrologyCleveland ClinicCleveland, Ohio

REPLY BY AUTHORS

The Lower Pole Study Group chose to focus on maximal stonediameter as this is the standard that has been used worldwide forclassifying nonstaghorn stones. The references cited by Streem re-garding the use of stone surface area refer to staghorn calculi andwere never intended nor suggested to be used for “all research,presentations and publications.” The Lower Pole Study Group usedthe same criterion in categorizing stones, namely that of maximalstone diameter, as this is the standard universally used by urologistsand is pervasive in the literature relating to outcomes for nonstag-horn stone disease (JAMA, 260: 978, 1988; J Urol, 158: 1915, 1997).Moreover, few (if any) urologists currently use or have access to stonesurface area methodology.

The only universally agreed upon definition of successful stonetreatment is stone-free. Much has been written over the years re-garding residual stone fragments or “dust” and their significance.Streem has condemned use of the term “clinically insignificant re-sidual fragments” in a recent article (J Urol, 155: 1186, 1996).

Ultimately, clinical decision making is no better than the informa-tion used in the decision making process. This study provides themost objective data to date for urologists to use in counseling pa-tients regarding the outcomes of various treatment choices for thetreatment of lower pole calculi.

LOWER POLE NEPHROLITHIASIS2080