Radiology: Pancreatitis imaging doubles but doesn't improve outcomes

Patient is a 66-year-old male with a history of pancreatoduodenectomy for chronic pancreatitis. CT scan during pancreatitis episode shows peripancreatic inflammation without a dilated pancreatic duct. Image source: HPB (Oxford) 2005;7(2):124–128

The use of high-cost CT and MRI imaging in patients admitted for acute pancreatitis (AP) increased 2.5-fold yet was associated with no improvement to patient outcomes, according to a study published in the November edition of Radiology.

"Since 2000, the use of and expenditures for imaging services have increased more rapidly than any other physician-ordered service," noted Koenraad J. Mortele, MD, and co-authors from Brigham and Women's Hospital at Harvard Medical School in Boston. "Despite the potential benefits of these studies, a number of medical and economic risks are associated with diagnostic imaging. Therefore, referring physicians need to select the appropriate imaging technique to ensure cost-effective, high-quality patient care."

Acute pancreatitis (AP), a common inflammatory condition of the pancreas, accounted for more than 220,000 annual hospital admissions in the U.S. at an estimated cost of $2.2 billion in 2003. This was the first study to examine the current use of imaging for AP, the authors claimed.

A total of 252 adult patients admitted for AP between mid-2005 and the end of 2007 were included in the study, which tabulated the number of AP-related radiologic imaging studies within one year of patients' admission for AP. AP was defined as at least two of the following: characteristic abdominal pain (such as severe upper abdominal pain); serum amylase and/or lipase levels three or more times the upper limit of normal; or CT or MRI results demonstrating changes consistent with AP.

The average number of radiologic studies utilized per patient within one year of initial admission was 9.9. An average of 5.5 studies (totaling 1,324 during the study period) were administered during the initial hospital stay, generating an average of 3.9 relative value units (RVU).

The most common modalities utilized were chest radiography (38 percent of the total), abdominal CT (17 percent), pelvic CT (17 percent) and abdominal ultrasound (8 percent). Over the course of hospitalization, 54.8 percent of patients underwent at least one abdominal ultrasound study, 52.4 percent received at least one abdominal CT, 15 percent one or more MRI or MR cholangiopancreatographic exam and 13.5 percent underwent one or more endoscopic retrograde cholangiopancreatography exam.

Patients with longer hospital stays, higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores, higher pain levels, drug-induced AP and prior episodes of AP all underwent significantly more studies than other patients. Adjusting for these risks, the authors still noted a 2.5-fold increase in the average number of studies per patient over the course of the study.

"We observed a 2.5-fold increase in the use of high-cost (CT and MRI) radiologic exams for AP and a 1.4-fold increase in imaging RVUs per case-mix-adjusted admissions during the 2.5-year study period without detectable improvement in patient outcomes (measured with mortality, intensive care unit admission, need for surgery, presence of organ failure or presence of persistent SIRS).

"Therefore," the authors continued, "although it remains difficult to analyze the effect of imaging utilization on patient outcomes, it can probably be inferred that in our institution the increasing use of cross-sectional imaging did not result in a detectable improvement in outcomes for patients with AP." Mortele and colleagues expressed surprise that neither age nor the presence of comorbidity were associated with any increase in the number of studies ordered.

"Although speculative and without clear explanation for its cause," the authors conjectured, "it appears that in light of the mild disease in approximately 90 percent of our patients, CT and MR imaging usage exceed what is currently recommended by the American College of Radiology Appropriateness Criteria

"Moreover, to predict the clinical severity of AP, no advantage is likely conferred by performing early imaging compared with the simpler and more easily obtained clinical evaluation."

The authors noted several limitations to their study. For one, the results of the single facility study may not be generalizable to the rest of the country. In addition, although the authors did look at the overall association between increased imaging and patient outcomes, the research did not evaluate the appropriateness of use of the ordered studies, which the authors acknowledged to be important for the medical community as well as society at-large.

Emphasizing the risk of radiation overexposure and the high costs of the AP studies, the authors drew the conclusion that "CT should probably be used more selectively in those patients for whom the diagnosis is equivocal, in those who have severe AP predicted with clinical assessment, or in those who fail to improve clinically despite conservative therapy

"The overutilization of CT results in wasteful use of resources as well as unnecessary radiation exposure with its inherent risks ... without detectable improvement in patient outcomes."