Abstract: PD21-02
Sources of Funding: none

Introduction

The management of patients with ureterolithiasis who report resolution of their symptoms but do not recall passing the stone presents a clinical challenge. We sought to analyze the cost of differing management strategies for these patients.

Methods

We performed a cost minimization analysis using published efficacy data and Medicare reimbursement costs. We constructed a decision analysis tree (Fig 1) which we used to compare: a) ureteroscopy with planned lithotripsy; b) follow-up imaging to determine presence or absence of stone using computed tomography (CT), abdominal plain film (KUB), or ultrasound (US); or c) continued observation. We performed sensitivity analyses, varying threshold values, to determine the factors driving costs.

Results

Observation was associated with the lowest costs for patients when the probability of spontaneous stone passage was higher than 62% (Fig 2). Initial imaging with CT was the least costly approach for patients with an intermediate probability of stone passage, 21-62%. Proceeding directly with ureteroscopy was associated with the lowest costs when the probability of spontaneous stone passage was less than 21% (Stones about >8mm in size). When the sensitivity of US is modeled to be high (>79%), it surpasses CT scan as the least costly approach across a wide range of spontaneous passage rates

Conclusions

The probability of spontaneous passage of a ureteral stone can be used to optimize treatment strategies for patients. Observation minimizes costs for patients with stones likely to pass spontaneously, whereas ureteroscopy minimizes costs for stones unlikely to pass. For ureteral stones with an intermediate probability of spontaneous passage, CT imaging to guide treatment is associated with the lowest estimated costs.

Funding

none