Medical Explusion Therapy for Kidney Stones
Search strategy: Turning to the Evidence Based Medicine link on the Becker Medical Library Website, you locate the link to the TRIP database and enter the search term “kidney stones” which yields 249 “therapy” and 68 “systematic review” articles on MEDLINE. Unfortunately, none of the 68 SR’s discuss α-agonists in kidney stone management and you do not have the time to search 249 therapy abstracts. Therefore, you refine your TRIP search to “renal colic tamsulosin” which yields two PUBMED SR’s. One Annals of Emergency Medicine SR seems relevant so you click “related articles” and find another SR in Lancet. From these SR’s three of the articles you need are located. The fourth article you note while reading through EM Journal Watch.
A 40-year old female presents to your Emergency Department on Labor Day weekend with sudden onset, intermittent left flank pain over the last 4-hours. She notes no associated dysuria, hematuria, fevers, or abdominal pain. She has no PMH or PSH. After Tylenol failed to relieve her suffering, she proceeded to the ED for pain control. Your initial evaluation reveals a lean woman rolling around her bed in pain holding her left flank. She is hemodynamically stable without evidence of abdominal pain or any pulsatile abdominal mass. Although lacking any abdominal aortic aneurysm (AAA) risk factors, you astutely review her abdominal aorta on ultrasound (US) and note no AAA. Unfortunately, you are not adept at renal US so after discussing the risk-to-benefit trade-off of CT-imaging, you order a renal stone protocol CT.
The CT demonstrates an 8mm stone at the left ureterovesicular junction with moderate hydronephrosis. Concerned that this stone has a 15% chance of spontaneous passage, you consult your Urologist to ascertain further medical or surgical therapeutic options. Over the phone, your Urologist recommends tamsulosin and next day follow-up in her office. You question the benefit of an α-agonist so turn to the literature for an answer.
Population: Patients with symptomatic kidney stones
Intervention: α-agonist plus routine pain management
Control: Routine pain management alone
Outcomes: symptom duration, stone passage rate, pain control
Second years: Randomized Trial of the Efficacy of Tamsulosin, Nifedipine, and Spasmolytic in Medical Expulsive Therapy for Distal Ureteral Calculi, J Urol 2005; 174: 167-172. (http://pmid.us/15947613)
Article 1: SR of Medical Therapy for Kidney Stones — Annals EM 2007.pdf
Article 2: Tamsulosin or Nifedipine for Distal Ureteral Calculi RCT — J Urol 2005.pdf
Article 3: Alfuzosin for Distal Ureteral Calculi RCT — J Urol 2008.pdf
Article 4: Medical Therapy to Pass Kidney Stone Meta-analysis — Lancet 2006.pdf
Low-quality RCT’s suggest that both α-antagonists (primarily tamsulosin, NNT = 3) and nifedipine (NNT = 4) improve moderate sized (more than 5mm) distal kidney stone expulsion rates compared with standard medical therapy in very select ED patient populations. Calcium channel blockers may have more adverse side effects than α-antagonists (4% vs. 15%). Both therapies reduce the time to stone expulsion with upper limit of 95% CI 14-days (α-antagonists) or 28-days (CCB). Therefore, the duration of therapy should be 14-days for α –antagonists and 28-days for CCB. Alfuzosin should not be first-line α-antagonist used in MET for small (<4mm) distal ureteral kidney stones since this agent does not improve expulsion rates or clinically significant pain scores. Compared with ureteroscopy and lithotripsy, MET may save $2,000 – $4,000 per patient. Future large RCT’s will need to identify subjects of patients unlikely to respond to MET, adverse event rates, and the optimal MET agent, dosing, and duration of therapy.