STONE PLUS: Evaluation of Emergency Department Patients With Suspected Renal Colic, Using a Clinical Prediction Tool Combined With Point-of-Care Limited Ultrasonography

Abstract

Study objective-We determine whether renal point-of-care limited ultrasonography (PLUS) used in conjunction with the Sex, Timing, Origin, Nausea, Erythrocytes (STONE) clinical prediction score can aid identification of emergency department (ED) patients with uncomplicated ureteral stone or need for urologic intervention.Methods-This was a prospective observational study of adult ED patients undergoing computed tomography (CT) scan for suspected ureteral stone. The previously validated STONE score classifies patients into risk categories of low (≈10%), moderate (≈50%), or high (≈90%) for symptomatic stone. Renal PLUS assessed for presence of hydronephrosis before CT scanning. The primary outcomes of symptomatic ureteral stone or acutely important alternative finding were abstracted from CT reports. The secondary outcome, urologic intervention, was assessed by 90-day follow-up interview and record review.Results-Of 835 enrolled patients, ureteral stone was identified in 53%, whereas 6.5% had an acutely important alternative finding on CT. Renal PLUS modestly increased sensitivity for symptomatic stone among low and moderate STONE score categories. Moderate or greater hydronephrosis improved specificity from 67% (62% to 72%) to 98% (93% to 99%) and 42% (37% to 47%) to 92% (86% to 95%) in low-and moderate-risk patients, with likelihood ratios of 22 (95% CI, 4.2-111) and 4.9 (95% CI, 2.9-8.3), respectively. Test characteristics among high-risk patients were unchanged by renal PLUS. For urologic intervention, any hydronephrosis was 66% sensitive (57% to 74%), whereas moderate or greater hydronephrosis was 86% specific overall * Corresponding Author. brockdaniels@gmail.com. Author contributions: BD and CLM conceived the study. CPG, DS, and CLM and obtained research funding. SL and CLM supervised the conduct of the trial and data collection. SL participated in recruitment of patients. AM, SL, RJ, and CLM managed the data, including quality control. CPG and AM provided statistical advice. CPG, AM, and DS provided advisement on study design and methodology. BD, AM, RJ, and CLM analyzed the data. BD drafted the article and all authors contributed substantially to its revision. BD takes responsibility for the paper as a whole.Presented as an abstract at the Society for Academic Emergency Medicine annual meeting, May 2014, Dallas, TX.Clinical trial registration number: NCT01352676 HHS Public Access

Derivation of decision rules to predict clinically important outcomes in acute flank pain patients

“…The finding of hydronephrosis on renal point-of-care limited ultrasonography was shown to have a sensitivity of 66% and specificity of 58% for urologic intervention; moderate to severe hydronephrosis had a modest specificity (86%), but the sensitivity was diminished (36%). The addition of renal point-of-care limited ultrasonography modestly improved risk stratification of the STONE score [31]. Age and elevated white blood cell count are known predictors of ureteral stone requiring urologic intervention [17,32].…”

Ultrasound vs. Computed Tomography for Severity of Hydronephrosis and Its Importance in Renal Colic

“…We chose to perform follow up at 30 days based on the recommended trial of medical expulsion therapy of 4–6 weeks 8,10,41,42. Two prior studies found moderate and severe hydronephrosis to be more predictive of the need for urologic intervention 17,32. A smaller prospective study analyzed the test characteristics of severity of hydronephrosis and stone size >5mm on risk of 30-day hospitalization in renal colic patients and found any hydronephrosis to be 100% sensitive and 44% specific 31.…”

“…However, as many as 50% of patients diagnosed with renal colic will have recurrent episodes and may receive multiple CTs throughout their lifetime, adding to costs, increased length of stay, and radiation exposure 10–13. There are currently no validated practice guidelines for the diagnosis and ED management of renal colic; thus, the need for a multidisciplinary approach to managing this disease is clear 12,14–17…”

The “Sinking” STONE

“…If CT is desired to delineate stone size and location, this is an optimal population for reduced-dose CT. 8 High likelihood of ureteral stone has been consistently associated with low likelihood of alternate diagnoses in the initial retrospective, prospective, and external validations. [2][3][4][5]7 The recent editorial also raised the question of whether risk stratification is necessary when a clinician believes that a CT scan is warranted. That is precisely when risk stratification is needed: when the clinician is about to press the "order" button.…”