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A Decision Analysis of Observation vs. Immediate Re-Intervention for Asymptomatic Residual Fragments &lt 4mm Following Ureteroscopic Lithotripsy
Michal Ursiny, M.D.¹, Alan Yaghoubian, M.D.¹, Mitchell Humphreys, M.D.², Hilary Brotherhood, M.D.³, Benjamin Chew, M.D.³, Manoj Monga, M.D.⁴, Amy Krambeck, M.D.⁵, Cameron Charchenko, M.D.⁶, An Qi Wang, B.S.⁷, Roger Sur, M.D.⁷, Nicole Miller, M.D.⁸, Tracy Marien, M.D.⁸, Yui-Hui Chang, B.S.⁶, Bodo Knudsen, M.D.⁹, Courtney Yong, M.D.¹⁰, Brian Matlaga, M.D.¹¹, Ojas Shah, M.D.¹², Vernon Pais, M.D.¹³, Brian Eisner, M.D.¹.
¹Massachusetts General Hospital, Boston, MA, USA, ²Mayo Clinic Arizona, Phoenix, AZ, USA, ³University of British Columbia, Vancouver, BC, Canada, ⁴Cleveland Clinic, Cleveland, OH, USA, ⁵University of Indiana, Indianapolis, IN, USA, ⁶Mayo Clinic, Rochester, MN, USA, ⁷UCSD, San Diego, CA, USA, ⁸Vanderbilt University, Nashville, TN, USA, ⁹Ohio State University, Columbus, OH, USA, ¹⁰University of Iowa, Iowa City, IA, USA, ¹¹Johns Hopkins University, Baltimore, MD, USA, ¹²Columbia University, New York, NY, USA, ¹³Dartmouth-Hitchcock Medical Center, Hanover, NH, USA.

Background: To assess the cost-effectiveness of observation vs. intervention on asymptomatic residual fragments less than 4mm in diameter following ureteroscopic laser lithotripsy using a decision analysis model. Methods: Outcomes data from a retrospective analysis evaluating the natural history, complications, and re-intervention rates of asymptomatic residual stone fragments performed by the EDGE consortium were utilized. A decision analysis model was constructed to compare the cost-effectiveness of initial observation of residual fragments compared to immediate intervention. Cost for the observation arm consisted of ED visits, hospitalizations, and re-interventions. The cost-analysis model extended for 3 years to account for delayed re-intervention rates on fragments of this size. For the immediate intervention arm, costs for ureteroscopy and shockwave lithotripsy were accounted and weighted depending on actual usage. Expected value calculations and sensitivity analyses were performed to determine the optimal treatment pathway based on overall cost-effectiveness inclusive of equipment, secondary costs from complications, emergency department visits, hospital readmission, and re-interventions. Costs of emergency department visits, readmissions, and re-interventions were calculated based on published figures from the literature. Results: Two hundred thirty-two patients were found to have asymptomatic residual fragments &lt 4mm on follow-up imaging following ureteroscopic lithotripsy. There were 191 patients in the observation group and 41 in the immediate-intervention group. Decision analysis modeling demonstrated that when comparing initial observation to immediate re-intervention, the cost was $2965 vs. $4504, respectively. The difference in cost was largely driven by the fact that over 3 years, approximately 56% of patients remain asymptomatic and thus incur no ED visit, hospitalization, or re-intervention costs. This represents an approximate annual per-patient savings of $513, and $1539 over three years when observation is selected over immediate re-intervention. Conclusion: Our decision analysis model demonstrates superior cost-effectiveness for observation over immediate re-intervention for asymptomatic residual stones &lt 4mm following ureteroscopic lithotripsy. The cost-savings are primarily due to a plurality of patients not requiring intervention if observed. Based on these findings, careful stratification and selection of patients may enable surgeons to improve cost-effectiveness of managing small, asymptomatic residual fragments following ureteroscopic lithotripsy.

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