Early surgical intervention is an attractive option for acute ureteral colic, but existing evidence does not clarify which patients benefit. We compared treatment failure rates in patients who received early intervention and patients who were offered spontaneous passage to identify subgroups benefiting from early intervention.
Materials and methods:
We used administrative data and structured chart review to study consecutive patients presenting to 9 emergency departments in 2 Canadian provinces with confirmed ureteral stones of 2.0 to 9.9 mm.
We described patient, calculation, and treatment characteristics, and performed multivariable regression to identify factors associated with treatment failure, defined as intervention or hospitalization within 60 days. Our secondary outcome was the rate of emergency department visits.
Results:
In total, 1,168 of 3,081 patients underwent early intervention. Those with stones smaller than 5 mm experienced more treatment failures (31.5% vs 9.9%, difference 21.6%, 95% CI 16.9 to 21.2) and emergency department visits ( 38.5% versus 19.7%, difference of 18.8%, 95% CI: 13.8 to 23.8) with early intervention than with spontaneous passage.
Patients with stones 7.0 mm or larger experienced fewer treatment failures (34.7% vs 58.6%, risk difference 23.9%, 95% CI 11.3 to 36.6) and similar rates of revision to the emergency department with early intervention.
Patients with stones 5.0 to 6.9 mm had fewer treatment failures with the intervention (37.4% vs. 55.5%, risk difference 18.1%, 95% CI: 7.1 to 28.9) if the stones were in the proximal or middle ureter.
Discussion
This is one of the largest studies to date evaluating the management of ureteral colic. We found that approximately 30% of early intervention patients required subsequent hospital care regardless of stone size.
Anecdotally, most returned due to stent pain, incomplete stone removal, or continued pain in patients who expected their pain to resolve immediately after the procedure. In contrast, among patients with spontaneous passage, morbidity was low for those with small stones and increased linearly with stone size.
| Based on these findings, we propose that patients with stones less than 5 mm generally be offered spontaneous passage as initial treatment, while those with proximal or middle ureteral stones larger than 5 mm, or any stones larger than 7 mm, they are offered early intervention. |
Early intervention is intuitively appealing. It removes the offending stone and relieves obstruction, but bleeding, infection, pain from clots or stents, ureteral edema or spasm, or incomplete stone removal may increase morbidity in low-risk patients.
Comparing spontaneous passage with early intervention has left the indications for early intervention unclear. No trials have compared the intervention with spontaneous passage and studies of emergency intervention have limitations. Most report stone-free success and some report procedural complications, but none have patient-oriented controls or outcomes.
Several authors have concluded that emergency intervention is safe and effective based on high stone-free rates and relatively few complications, but without measuring other outcomes. Hollingsworth et al reported that early intervention resulted in higher costs, similar subsequent hospitalization rates, and fewer ED visits than medical treatment.
However, this study included only men and excluded patients who underwent stent placement, a common source of morbidity. Because the data were derived from insurance claims, covariates such as stone size and location were not taken into account and likely differed between groups.
Dauw et al compared early intervention patients with propensity-matched controls and found that disability and costs were higher for intervention patients, but this study also lacked important clinical covariates.
A 2014 analysis of data from Ontario showed that increasing intervention rates were associated with greater post-treatment morbidity. (ER visits and hospitalizations), and a 2018 cohort study comparing 2 health regions found a similar correlation between early intervention and post-treatment morbidity.
Several studies have described relationships between stone size, location, and passage success, but most have a small sample size. Coll et al reported expulsion rates of 48%, 60%, 75%, and 79% for proximal, mid, distal, and ureterovesical junction stones, respectively, but recruited only 10 to 62 patients per group, with only 40 stones. of more than 6 mm and only 3 calculations in some categories.
Papa et al found that larger, proximal stones predicted passage failure, but a sample of 245 patients limited precision within size and location subgroups.
Ueno et al concluded that stones smaller than 8 mm could be treated expectantly, but only 16 of 264 patients had stones larger than 6 mm. A recent study of 392 patients found that smaller stone size and increased hydronephrosis predicted passage success, but evaluated only 23 stones larger than 6.5 mm.
Another passage predictor described but studied only 16 stones larger than 4 mm. In a study of 378 patients, Morse and Resnick reported that 22%, 46%, and 72% of proximal, middle, and distal stones passed successfully, but did not provide size parameters.
A prospective cohort study of conservatively treated patients reported successful passage for 52%, 70%, and 83% of proximal, middle, and distal stones, and for 89%, 49%, and 29% of small ones ( less than 5 mm), medium (5 to 7 mm stones) and large (greater than 7 mm), respectively.
These findings are consistent with ours, but the study lacked an interventional comparator and therefore did not clarify the subgroups that would benefit from the intervention.
Transcendence
Existing guidelines are based primarily on small, older studies, do not discuss predictors beyond stone size, and may not generalize to current practice. We studied all eligible patients seen at 9 hospitals in 2 regions, a large sample that includes many patients with high-risk stones.
The variable practices across study sites provided a unique opportunity to evaluate low-risk patients exposed to the intervention, high-risk patients exposed to spontaneous passage, and the spectrum in between. This should improve the external validity of our findings.
Our derived risk stratification model, which adjusted for the effects of several important covariates, is more consistent with Canadian and European guidelines than with US ones. The latter recommend spontaneous passage for stones of 10 mm or less, 15 while the Canadian guidelines suggest a 5 mm threshold.
European experts advise intervention for stones unlikely to pass, but found insufficient evidence to specify a size limit and therefore agreed on a consensus threshold of 6 mm.6 Our data are based on previous research, which which supports a more targeted approach to early intervention.
Conclusions:
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