Transcript PPT - LSU School of Medicine

LSU Journal Club
Ultrasounography versus Computed
Tomography for Suspected
Nephrolithiasis
R. Smith-Bindman, C. Aubin, J. Bailitz, C.A. Camargo, Jr., J. Corbo, A.J. Dean, R.B.
Goldstein, R.T. Griffey, G.D. Jay, T.L. Kang, D.R.Kriesel, O.J.Ma, M. Mallin, W. Manson, J,.
Melnikow, D.L. Miglioretti, S.K. Miller, L.D. Mills, J.R.Miner, M. Mighadassi, V.E.Noble,
G.M. Press, M.L. Stoller, V.E. Valencia, J,. Wang, R.C.Wang, and S.R.Cummings
Abby Gandolfi, PGY 1
November 20, 2014
Background
• Cost of acute care for nephrolithiasis: 2 billion
annually
• Fairly common ED presentation, but lack of
consensus as to regarding initial imaging modality
• Abdominal CT is currently most common based on
sensitivity over ultrasound
Background
• Drawbacks to CT:
-Radiation exposure and long term risk of cancer
- Incidental findings
- Cost of CT, 2 billion a year acute care cost
• No evidence that diagnosis via CT leads to better
patient outcomes
Research question
• What is the effect of diagnostic imaging
techniques, specifically CT versus ultrasound,
on patient outcomes in the initial work up of
suspected nephrolithiasis?
• Compared ED physician-performed ultrasound
(point-of-care) radiologist performed
ultrasound, and CT
Research Question
• Primary outcomes
measured:
Any of the following diagnoses made within
30 days of initial ED presentation:
-AAA with rupture
-PNA with sepsis
-appendicitis with rupture
-diverticulitis with abscess or sepsis
-Bowel ischemia or perforation
-Renal infarct
-Renal stone with abscess
-Pyelonephritis with sepsis or bacteremia
-Ovarian torsion with necrosis
-Aortic dissection with ischemia
– high risk diagnoses
that could be
delayed or missed
– Cumulative radiation
exposure
– Total cost, not
reported in study
•Patients followed for 180 days after presentation
Research Question
Secondary Outcomes:
• Serious adverse events
• Serious adverse events related to study
participation
• Repeat ED visits and hospitalizations
• Patient reported pain score
• Diagnostic accuracy for nephrolithiasis
Confirmation of presence of stone within 6 months based on patient reported
stone passage or surgical removal
Study Design
• Multicenter, randomized, comparative
effectiveness trial
• October 2011 to February 2013
• Conducted across 15 ED’s at geographically
diverse academic medical centers
Study design
-Patients who
presented to the ED
with suspected
nephrolithiasis were
randomly assigned to
one of the three
imaging groups
-Randomization 1:1:1
via SAS software and
only occurred during
hours when all 3
modalities were
available
Study Subjects
• Compiled data of 2759 patients age 18
to 76, all were consented
• Patients selected if chief complaint
included flank or abdominal pain and if
the treating physician decided that
work up would include imaging to rule
out nephrolithiasis as primary diagnosis
Table 2:
Clinical Data and
Provisional
Diagnosis by
Emergency Dept
Physicians
Study Subjects
Exclusion criteria:
• High clinical suspicion for alternative, serious
diagnosis
• Pregnant women
• Men weighing more than 129kg or 285 lbs
• Women weighing more than 113 kg or 250 lbs
• Any patients with single kidney, s/p kidney
transplant, or dialysis patients
Results: Primary Outcomes
Results: Primary Outcomes
• Cumulative radiation exposure was significantly lower in
patients who underwent ultrasound
• 11 patients were identified with an alternative high risk
diagnosis,
– 6 patients in the point of care ultrasound group
– 3 patients in the radiology ultrasound group
•
2 patients in the CT group
• No statistically significant difference among imaging modality
when a serious alternative diagnosis was made
Results: Secondary Outcomes
Results: Secondary Outcomes
•
Adverse events
– no significant difference
•
ED length of stay
– Longer time in ED for radiology ultrasound and CT groups
•
Return ED visits
– No statistical difference among groups
•
Diagnostic accuracy
– Based on result of initial imaging showed ultrasound had lower sensitivity and higher specificity
sensitivity 54% POC, 57% radiology u/s, 88% CT
specificity 71% POC, 73% radiology u/s, 58% CT
– Based on confirmation of stone within 6 months, sensitivity and specificity for diagnosis were
similar across 3 groups
– Patients who underwent u/s initially more likely to undergo subsequent testing
• 40% pts with point of care u/s got a subsequent CT
• 27% of pts with radiology u/s got a subsequent CT
• 5% of pts who got initial CT got additional ultrasound
Conclusions
• Authors conclude that ultrasound should be initial
test of choice in suspected nephrolithiasis
– Lower total radiation
– No significant difference in missed high risk
diagnosis
– Though more u/s patients had subsequent CT,
most u/s patients did not undergo any additional
imaging
Conclusions
• Start evaluation with ultrasound and then obtaining
additional imaging based on clinical judgment
• Patients with history of nephrolithiasis have likely
had high cumulative radiation exposure, ultrasound
preferred here
• CT has greater sensitivity, but did not translate to
better outcomes
• As expected, point of care u/s had shortest length of
stay but highest incidence of subsequent CT