Does volume matter? Incorporating estimated stone volume in a nomogram to predict ureteral stone passage

Authors

  • Nassib Abou Heidar Division of Urology, Department of Surgery, American University of Beirut Medical Center, Beirut, Lebanon
  • Muhieddine Labban Division of Urology, Department of Surgery, American University of Beirut Medical Center, Beirut, Lebanon
  • David-Dan Nguyen Faculty of Medicine and Health Sciences, McGill University, Montreal, Canada
  • Adnan El-Achkar Division of Urology, Department of Surgery, American University of Beirut Medical Center, Beirut, Lebanon
  • Mazen Mansour Division of Urology, Department of Surgery, American University of Beirut Medical Center, Beirut, Lebanon
  • Naeem Bhojani Division of Urology, Department of Surgery, Centre hospitalier de l’Université de Montréal, Montreal, Canada
  • Rami Nasr Division of Urology, Department of Surgery, American University of Beirut Medical Center, Beirut, Lebanon

DOI:

https://doi.org/10.5489/cuaj.7364

Keywords:

Ureteral stone, spontaneous passage, stone volume, predictive nomogram

Abstract

Introduction: Recent studies have shown that software-generated 3D stone volume calculations are better predictors of stone burden than measured maximal axial stone diameter. However, no studies have assessed the role of formula estimated stone volume, a more practical and less expensive alternative to software calculations, to predict spontaneous stone passage (SSP).

Methods: We retrospectively included patients discharged from our emergency department on conservative treatment for ureteral stone (≤10 mm). We collected patient demographics, comorbidities, and laboratory tests. Using non-contrast computed tomography (CT) reports, stone width, length, and depth (w, l, d, respectively) were used to estimate stone volumes using the ellipsoid formula: V=π*l*w*d*0.167. Using a backward conditional regression, two models were developed incorporating either estimated stone volume or maximal axial stone diameter. A receiver operator characteristic (ROC) curve was constructed and the area under the curve (AUC) was computed and compared to the other model.

Results: We included 450 patients; 243 patients (54%) had SSP and 207 patients (46%) failed SSP. The median calculated stone volume was significantly smaller among patients with SSP: 25 (14–60) mm3 vs. 113 (66–180) mm3 (p<0.001). After adjusting for covariates, predictors of retained stone included: neutrophil to lymphocyte ratio (NLR) ≥3.14 (odds ratio [OR] 6, 95 % confidence interval [CI] 3.49–10.33), leukocyte esterase (LE) >75 (OR 4.83, 95% CI 2.12–11.00), and proximal stone (OR 2.11, 95% CI 1.16–3.83). For every 1 mm3 increase in stone volume, the risk of SSP failure increased by 2.5%. The model explained 89.4% (0.864–0.923) of the variability in the outcome. This model was superior to the model including maximal axial diameter (0.881, 0.847–0.909, p=0.04).

Conclusions: We present a nomogram incorporating stone volume to better predict SSP. Stone volume estimated using an ellipsoid formula can predict SSP better than maximal axial diameter.

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Published

2021-10-18

How to Cite

Abou Heidar, N., Labban, M. ., Nguyen, D.-D. ., El-Achkar, A. ., Mansour, M. ., Bhojani, N. ., & Nasr, R. (2021). Does volume matter? Incorporating estimated stone volume in a nomogram to predict ureteral stone passage. Canadian Urological Association Journal, 16(3), E150–4. https://doi.org/10.5489/cuaj.7364

Issue

Vol. 16 No. 3 (2022): CUAJ March

Section

Original Research

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