EBQ:Ultrasound versus Computed Tomography for Suspected Nephrolithiasis

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incomplete Journal Club Article
Smith-Bindman, R., Aubin, C., Bailitz, J., Bengiamin, R.N., Camargo, C.A. Jr., Corbo, J. et al,. "Ultrasonography versus Computed Tomography for Suspected Nephrolithiasis". New England Journal of Medicine. 2014. (371):1100–1110.
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Clinical Question

What is the initial imaging method for patients with suspected nephrolithiasis presenting to the emergency room?

Conclusion

Ultrasound is less sensitive than CT for the diagnosis of nephrolithiasis and can be used as an initial test for patients with suspected nephrolithiasis 

Ultrasound first as the initial imaging method can result in no CT for the most patients, lower cumulative radiation exposure no significant difference in the risk of subsequent serious adverse events Pain scores Return ED visits Hospitalizations


Major Points

Ultrasound either point-of-care or radiology was associated with a lower cumulative radiation exposure than CT without significant differences in high-risk diagnoses, serious adverse events, pain scores, return emergency department visits, hospitalizations or diagnostic accuracy in patients 18-76 years old presenting to the emergency department with suspected nephrolithiasis.

Study Design

Multicenter, pragmatic, comparative effectiveness trial 

3638 patients were screened 3100 eligible 2759 patients (89% of eligible patients) underwent randomization with 908 in the point of care ultrasound, 893 to radiology ultrasound and 958 to CT scan

No significant difference in three groups with respect to gender, age, race, self=report pain score or hospital admission after being seen in the ED

Past medical history of kidney stones, cancer, diabetes and hypertensioin were not significantly different across the three groups.

Of note, 41.6% had history of kidney stones 63.3% had hematuria 52.5% had costovertebral- angle tenderness


Physical exam findings of costoverbetral angle tenderness , right lower quadrant tenderness, left lower quadrant tenderness, murphy’s signs, McBurney’s sign, guarding as well as physicians estimated likelihood of kidney stones were obtained for the three groups with no significant difference.

Patients were contacted at 3, 7, 30, 90 and 180 days to assess study outcomes


Population

18 to 76 years old who presented to the emergency department with suspected nephrolithiasis who presented to the Emergency room in one of the 12 emergency departments


Patient Demographics

Inclusion Criteria

18-76 years of age who reported flank or abdominal pain with ED physician who was planning to order imaging to establish or rule out primary diagnosis of kidney stones

Exclusion Criteria

Patients who the ED physician deemed were at high risk for alternative diagnoses including acute cholecystitis, appendicitis, aortic aneurysm, or bowel disorders Pregnant women Men more than 129 kg Women more than 113 kg Single kidney History of renal transplant Undergoing dialysis


Interventions

Initial imaging based on randomization with point-of- care ultrasound examinations performed by ED physicians who had training as recommended by ACEP, radiology ultrasound performed in radiology department per guidelines and CT performed according to local standards. 


Outcomes

Primary Outcome

30 day incidence of high risk diagnoses (abdominal aortic aneurysm with rupture, pneumonia with sepsis, appendicitis with rupture, diverticulitisi with abscess or sepsis, bowel ischemia or perforation, renal infarction, renal stone with abscess, pyelonephritis with urospesis or bacteremia, ovarian torsion with necrosis or aortic dissection with ischemia) with complications that could be related to missed or delayed diagnosis

6 month cumulative radiation exposure (calculated by amount of radiation per CT scan as well as reviewing medical records to see if patient had any repeat radiation exams)

Secondary Outcomes

Serious adverse events (death, life-threatening, required hospitalization, caused persistent or clinically significant diability or required medical, surgical or other intervention to prevent permanent impairment ) 16 

Related serious adverse events –three people analyzed all 466 serious adverse events and rated each on as definitely, probably, possibly related, unlikely to be related, or not related to initial randomization Pain (11 point Visual Analogue Scale) Return emergency department visits Hospitalizations Diagnostic accuracy (compared diagnostics to either patient’s personal observation of stone passage or surgically removed)


Subgroup analysis

Ultrasound has lower sensitivity with greater specificity than CT. 

POC US (Sensitivity, Specificity) (54%, 71%) Radiology US (Sensitivity, Specificity) (57%, 73%) CT scan (Sensitivity, Specificity) (88%, 58%)


Criticisms & Further Discussion

No statistical difference based on imaging method for the incidence of high risk diagnosis or related adverse events

was low at 0.4% and did not vary based on imaging method The ultrasound group had statistically significantly lower mean 6 month cumulative radiation exposure compared to the CT group No statistical difference in serious adverse events in all three groups (12.4% of the point of care ultrasound, 10.8% in radiology ultrasound, 11.2% in CT) No statistical difference in the average pain score, return emergency department visits, hospitalizations and diagnostic accuracy in all three groups

Patients in the ultrasonography groups were more likely that those in the CT group to have additional diagnostic testing during the emergency department visit with 40.7 % of the point of care ultrasound group and 27.0% of the radiology ultrasound group to have a CT scan performed. Only 5.1% of the CT group underwent ultrasound.

Investigators, patients and physicians were not blinded to the study group assignments Diagnosis of stone is a very strict definition which was unbiased but some participants might foreget that they passed a stone Point of care ultrasound was performed by emergency physicians that have had training and certification in ultrasound and this might not be present in all emergency rooms


External Links

See Also

Funding

References