Which patients are most likely to benefit?
Studies have shown that MET seems beneficial in certain stone patients but not in others.
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The most recent meta-analysis by Hollingsworth et al in The BMJ highlighted when MET is most beneficial, according to Dr. Preminger.
“Besides being more effective to facilitate the passage of distal ureteral calculi, MET appears to be most beneficial in larger stones—5 mm or greater. This finding makes sense because if you have a stone that’s only 3 mm to 4 mm, chances are that stone is going to pass whether [or not] you prescribe MET,” Dr. Preminger said. “I would offer that you should use MET in stones 5 mm or greater, and it’s a toss-up whether you use it for smaller stones.”
Dr. Nakada said he’s more likely to recommend surgical intervention for stones approaching 1 cm with obstruction and symptoms, rather than wait out MET therapy. He does, however, usually prescribe MET for patients with smaller distal stones and for patients who have a history of passing stones.
Both urologists prescribe tamsulosin because, they say, that’s the drug most used in studies. But all three commonly prescribed alpha-blockers—doxazosin, terazosin, and tamsulosin—have been shown to have similar efficacy in this off-label use, according to Dr. Nakada.
“We prefer tamsulosin. We’ve found that it’s well tolerated in males and females,” Dr. Preminger said. “It’s still our routine that when a patient is seen in the emergency department in our institution, if the patient is able to be sent home and doesn’t need emergent treatment, we will routinely give them tamsulosin, 0.4 mg daily. We’ll see the patient back in 4 to 6 weeks for follow-up imaging, and to make the decision whether or not further surgical intervention is warranted.”
Big-picture benefits, drawbacks
Generic MET doesn’t greatly impact health care costs, either positively or negatively, according to Dr. Nakada.
“The drug is not that expensive, and you would give it really for a short course—studies indicate 2 to 4 weeks,” Dr. Nakada said. “Potentially, if it were successful, this approach would lower health care expenditures because people wouldn’t need surgery.”
Where it might have greater impact is on disease-specific health-related quality of life, according to Dr. Nakada.
“If you can avoid more surgery and pass more stones, that would substantially improve the patients’ health-related quality of life related to stones. We have a large cooperative group studying this using our quality of life instrument,” he said. That study should be out in the next year.
Data already show that MET can reduce pain and time to stone expulsion (by 5 to 7 days) and emergency room visits, according to Dr. Nakada.
“Those are the historical studies and include the use of steroids. Similar findings were not identified by The Lancet study,” he said.
Drawbacks of prescribing MET are minimal.
“The side-effect profile for tamsulosin is good. Generally, less than 10% of people get any significant side effects. Anecdotally, the elderly and some women tend to struggle more with an alpha-blocker than men, with hypotension and nasal stuffiness being the main common side effects,” Dr. Nakada said.
Dr. Preminger said that in his experience, orthostatic hypotension is more common in older patients and is less common in the age groups normally treated for kidney stones.