EAU 2018: Medical Expulsive Therapy Has No Benefit in Improving Spontaneous Stone Passage in Patients Presenting with Acute Ureteric Colic: Results from the MIMIC Study

Copenhagen, Denmark (UroToday.com) Medical expulsive therapy (MET), or the use of pharmaceuticals to facilitate spontaneous stone passage, has not had the benefit of Level 1 evidence to guide its use in patients with acute ureteric colic. Previous studies have been underpowered, particularly due to high variation in stone size and stone position in the ureter; even further, subset analysis has not shown MET to be advantageous and fails to adjust for potential confounders.

Dr. Shah (MD) of the British Urology Researchers in Training (BURST) group, presented a multi-institutional and international cohort study of 71 centers assessing whether the use of MET increased rates of spontaneous stone passage in patients with acute ureteric colic. Unique to this study is its use of mixed effects multivariable logistic regression models, in effort to control for covariates such as age, gender, stone size, and stone position.

Of the 4181 patients with acute ureteric colic in the study, 3127 were discharged with conservative management. 952 (44%) were prescribed tamsulosin as MET intervention, while the remaining 1234 (56%) were not. Of note, the former group was noted to be older (47.5 vs. 46 yrs of age) than the latter.

Overall, 2516 (80%) of the patients experienced the primary outcome of spontaneous stone passage – this cohort of which was ultimately included in the multivariate model. MET use was included in this final model, along with the interaction terms for the above mentioned confounders.

In simple regression, MET use was a statistically significant indicator of spontaneous stone passage (OR 1.250, 95% CI 1.041 – 1.501). However, the authors note that the effect was small in absolute numbers, reflecting the difference between 78% and 72% in the MET usage group and the non-MET usage group. Similarly, after multivariable analysis, there was no association of MET with spontaneous stone passage in the overall and subgroup analysis of stone size or stone position.

Dr. Shah notes that a possible limitation of this study is the exclusion and inclusion criteria, as 300 patients of the initial cohort were excluded as MET use was unable to be confirmed. In addition, this patient cohort was noted to have a smaller average stone size (4mm, range 3-5mm) than other studies showing an advantage to MET use in conservative management.

Because the spontaneous stone passage in this cohort was particularly high, however, the study team does recommend conservative management for patients with acute ureteric colic. Whether this management benefits from MET use via tamsulosin, however, has not been proven and thus should not be routinely used in this patient cohort.

Presented by:  Shah T.T. MD, British Urology Researchers in Surgical Training (BURST), Urology Research Collaborative , London, United Kingdom

Written by: Linda M. Huynh, BS, (Department of Urology, University of California-Irvine) at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark