Presentation Authors: Ryan McLarty*, Mark Assmus, Timothy Wollin, Shubha De, Edmonton, Canada
Introduction: Many outcome-based studies have utilized patient reported accounts to establish stone passage rates, however little data exists regarding the accuracy of such assessments. We sought to prospectively quantify the accuracy of patient reported variables on true ureteric stone expulsion rates.
Methods: New patients presenting to the University of Alberta stone clinic were prospectively surveyed between April 2016 and November 2017. Current patient symptoms and an assessment of whether or not they believed they had passed their stone were assessed. Exclusion criteria included non-ureteric stones, sepsis, prior ureteric stent or operative intervention for the current stone episode. The primary outcome was radiographic stone passage as confirmed by ultrasound with KUB, CT scan, or ureteroscopy. Radiographic stone passage was compared to patient survey responses to calculate sensitivity and specificity.
Results: 136 patients met inclusion criteria with an average follow-up of 16.9Â±8.0 days from diagnosis. 69.5% were male, 50% were distal stones, average stone size was 6.8Â±3.2 mm, and 43.3% of patients had radiographically confirmed stone passage at first visit. 58% of patients who reported cessation of pain had passed their stone. Furthermore, only 77.7% of patients who believed they had passed their stone had actually passed it. Cessation of pain at the time of assessment demonstrated a sensitivity of 79.7% (67.1-89.0%, 95%CI) and a specificity of 55.8% (44.0-67.1%, 95%CI) for true ureteric stone expulsion. Patient reported stone passage had a sensitivity of 59.3% (45.7-71.9, 95%CI) and a specificity of 87.0% (77.4-93.5%, 95%CI) for true ureteric stone expulsion.
Conclusions: This is the largest prospective cohort study to assess patient reported outcomes on ureteric stone expulsion. Cessation of pain displayed a high sensitivity for predicting ureteric stone expulsion while patient reported stone passage had a high specificity. Both assessments may incorrectly assess ureteric stone expulsion, which raises concern for their validity as a clinical endpoint.