Renal colic really hurts, believe me I know! It’s one of those conditions that we see in emergency medicine where it really does not matter who you are, if you have good going colic you will be in agony. In terms of management then we know that early, good quality analgesia is the way to go. In #Virchester we often use a combined approach with NSAIDs and paracetamol as first line followed by opiates in the group of patients who don’t settle with NSAIDs (or who are intolerant of them).
Once we’ve got pain under control then we get a rapid CT KUB to assess whether there is any obstruction, the location of the stone and its size. For patients who’s pain can be managed, where there is no significant obstruction, no signs of infection, normal renal function, and where the stone is less than 9mm in diameter patients can be managed as an out-patient with Urology follow up.
What’s more controversial is whether we can aid the passage of a stone using MET (Medical Expulsive Therapy), typically with Tamsulosin or Nifedipine. There was a lot of enthusiasm for this in the past, but the evidence has not really stacked up to be decisive. Although there are meta-analyses and systematic reviews out there that are postive the methodological quality and patient groups have questioned the validity of the recommendations. In the UK they are considered a possible second line therapy by NICE1, but it’s hardly a firm endorsement. In the #FOAMed world colleagues have questioned the use of these drugs on several occasions2–4, but they are still used frequently in clinical practice.
— Salim R. Rezaie (@srrezaie) June 29, 2018
This month we have more evidence to help inform the debate. A Randomised Controlled trial of emergency department patients with a diagnosis of renal colic5. I think this is one of the largest to date (Ed – recent Lancet trial bigger6) and so may help us answer the question of whether Alpha blockers help aid the passage of renal stones.
The abstract is below, but as always we strongly suggest that you read the full paper.
What kind of study is this?
It’s an RCT, which, since we are looking at a therapeutic intervention is one of the optimal designs. Patients were randomised to receive either 0.4mg Tamsulosin or Placebo for 28 days. Patients were randomised between the two groups using the simple urn method – which is not a method I’ve come across before. I thought it meant picking the selection out of an urn (or I presume some sort of box would work), but it might be more complex than that (stats nerds can click here7,8 for an explanation). In the era of computers the idea of picking selections out of an urn seems quaint, but as the papers suggest I think it’s more complex than that. This paper is actually a continuation of the STONE pilot study that recruited in 2008-2009. Patients from both cohorts were analysed together. They were not able to have 24/7 recruitment sadly (which may be an issue for this condition).
What about the patients?
This is an ED study with adult patients (over 18) and a CT KUB diagnosis of renal colic and a stone <9mm. So pretty close to the group of patients we see in Virchester. The usual exclusions were in place to avoid patients with renal impairment, sepsis, severe pain or severe obstruction getting discharged. That does mean that they are typical of the patients we would manage as an out patient in Virchester. Overall 512 patients were recruited, 109 of whom were from the first cohort in 2008-2009.
What about the outcome measures.
The primary outcome measure was natural stone passage within 28 days, as defined by the patient seeing it pass, or capturing it. Patients were contacted up to 90 days post randomisation and in the latter cohort they had a repeat CTKUB at 28 days. There is an issue here with different outcomes for the two cohorts (although the primary outcome remains the same, CT is arguably a better test than physically noticing the stone pass). We can see this as the expulsion rates on CT (second cohort) are much higher than those reported by the patients, roughly 30% higher than patient reported in fact. I’m a bit uncomfortable with this as they did find a 6% difference in favour of Tamsulosin in the CT evaluated group. However, secondary outcomes were still the same and so the clinical importance of this is questionable.
And the results?
Let’s keep this brief. In terms of the overall success rate there was really no difference between Tamsulosin and Placebo with success rates of 49.6% vs 47.3%. They adjusted the results with regard to age, recruiting site, location and size and there was still no difference. However, some of the subgroup analysis was pretty small numbers with large confidence intervals (e.g. for upper ureter location).
The bottom line?
It’s still a bit tricky as there are plenty of studies, guidelines and reviews that advocate MET for renal colic patients. However, this trial and other higher quality large trials in ED patients (what I’m interested in6) fail to show an effect. At the moment it seems that we cannot advocate the routine use of Tamsulosin in our renal colic patients.
We may still get further trials that look at subgroups and which use a more robust outcome measure, but for now like many other #FOAMites, we think the evidence is pretty weak for use in ED patients.
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