Medical Expulsive Therapy versus Early Endoscopic Stone Removal for Acute Renal Colic: An Instrumental Variable Analysis

Abstract

Introduction and objective

Use of medical expulsive therapy (MET) to hasten stone passage potentially lowers expenditures around episodes of renal colic; however, these efficiency gains may be mitigated if patients treated with MET have frequent healthcare encounters due to pain while waiting for their stones to pass.

Methods

Using claims data (2002 – 2006), we identifed adult men with acute renal colic. We compared 6-week payments, as well as the frequency of hospitalization and ED revisit associated with an initial course of MET with those of early endoscopic stone removal. To account for unmeasured confounding, we performed an instrumental variable analysis, exploiting variation in recommended treatment based on the day of week that a patient’s first emergency department (ED) visit occurred.

Results

1,835 and 4,397 men received MET or early endoscopic stone removal, respectively. Although minimal differences existed between men with respect to the day of week of their ED presentation, weekend encounters were strongly associated with MET receipt (P<0.001). Two-stage least squares regression revealed 6-week payments to be 10-fold lower for men on MET who were candidates for either treatment (P<0.001). While there was no difference in their frequency of hospitalization, these men were more likely to have an ED revisit when compared with those who underwent endoscopic stone removal (68.8% versus 39.6%, respectively, P=0.025).

Conclusions

Findings on MET are mixed, with lower 6-week payments but more frequent ED revisits. These data inform patients, who are candidates for MET or endoscopic stone removal, when making decisions about their care.

http://www.jurology.com/article/S0022-5347(13)03687-2/abstract