Validation of a Decision Rule to Limit CT Scanning in Suspected Renal Colic

Trial Information

Validation of a Decision Rule to Limit CT Scanning in Suspected Renal Colic

Study Aim: The specific aim of this study is to prospectively validate the previously
derived decision rule for obtaining a Flank Pain Protocol (FPP) CT scan in suspected renal
colic.

The investigators will integrate the derived clinical decision rule from the ongoing
retrospective analysis with gestalt clinician pre-test probability, point of care
ultrasound, and plain radiography (when appropriate) to prospectively and observationally
test the rule at two distinct clinical settings. CT results and 90-day follow-up will be
used to determine predefined outcomes.

Study Hypothesis: Prospective observational testing of a clinical decision rule, combined
with point of care ultrasound and plain radiography when appropriate, will categorize >85%
of patients who will require intervention, validating a decision rule to avoid unnecessary
CT.

This amendment comes from recent evidence and work at our institution to develop an
"ultra-low dose" CT scan protocol (ULDCT) with an effective radiation dose close to that of
a plain film of the abdomen (KUB), or near 1mSv (compared to 8.5mSv in current practice).
While we expect the ULDCT to be better than a KUB at localizing and characterizing kidney
stones, what is unknown is how the loss in resolution with an ultra-low dose CT protocol
might affect this localization and characterization of stones relative to a regular dose CT
(current protocol), as well as the ability to find alternate diagnoses. Incorporating this
additional imaging study in a subgroup of patients during the observational phase will allow
us to determine test characteristics of the ULDCT that will allow incorporation into the
prospective phase. This will hopefully provide excellent evidence about how to implement an
ultra-low dose CT scan in practice, ultimately leading to a dramatic reduction in radiation
exposure for a large number of patients at Yale and other sites.

We filed an amendment 11-15-2011. This amendment comes from recent evidence and work at our
institution to develop an "ultra-low dose" CT scan protocol (ULDCT) with an effective
radiation dose close to that of a plain film of the abdomen (KUB), or near 1mSv (compared to
8.5mSv in current practice). While we expect the ULDCT to be better than a KUB at localizing
and characterizing kidney stones, what is unknown is how the loss in resolution with an
ultra-low dose CT protocol might affect this localization and characterization of stones
relative to a regular dose CT (current protocol), as well as the ability to find alternate
diagnoses. Incorporating this additional imaging study in a subgroup of patients during the
observational phase will allow us to determine test characteristics of the ULDCT that will
allow incorporation into the prospective phase. This will hopefully provide excellent
evidence about how to implement an ultra-low dose CT scan in practice, ultimately leading to
a dramatic reduction in radiation exposure for a large number of patients at Yale and other
sites.

This amendment comes from recent evidence and work at our institution to develop an
"ultra-low dose" CT scan protocol (ULDCT) with an effective radiation dose close to that of
a plain film of the abdomen (KUB), or near 1mSv (compared to 8.5mSv in current practice).
While we expect the ULDCT to be better than a KUB at localizing and characterizing kidney
stones, what is unknown is how the loss in resolution with an ultra-low dose CT protocol
might affect this localization and characterization of stones relative to a regular dose CT
(current protocol), as well as the ability to find alternate diagnoses. Incorporating this
additional imaging study in a subgroup of patients during the observational phase will allow
us to determine test characteristics of the ULDCT that will allow incorporation into the
prospective phase. This will hopefully provide excellent evidence about how to implement an
ultra-low dose CT scan in practice, ultimately leading to a dramatic reduction in radiation
exposure for a large number of patients at Yale and other sites.

Future Direction: Ultimately the investigators intend to implement the validated decision
rule at both study sites to evaluate further the feasibility, physician acceptance and
comparative effectiveness of our rule. Using standard dissemination techniques and
integration of the rule into the computerized physician order entry (CPOE) system at our
institutions the investigators will determine the actual reduction in the number of FPP CT
scans ordered, clinical outcomes based on 90-day follow up, survey of physician acceptance
of the rule as well as an comparative effective analysis. The investigators will submit an
application at a later date nearing the end of our projected enrollment for this study.