Our example of a cost-recovery model for ED CTAP
Our ED installed a CT scanner initially for assessing poly-trauma and stroke patients. Later, the EPs (sometimes with the surgeons’ inputs) began to order CTAPs for patients with acute abdomen. Initially, the costs of performing CTAPs in the ED were absorbed by the hospital, under the flat fee of SGD140 for each emergency attendance (SGD80 paid by patient and SGD60 from government subvention). This meant a loss for the hospital as each CTAP costs about SGD700 (without subvention).
After 2015, patients were asked to pay for ED CTAPs themselves, if they are not admitted. It was charged at SGD350 (after 50% subvention). Should the CTAP show a condition that necessitated emergency admission, then the cost would be rolled over and included into the inpatient bill instead of the ED charges. Patients could choose to pay part or all of their hospitalisation bills with own savings, private insurance or from Medisave (national health savings scheme). Patients could choose to have their CTAPs done in the ED or ward, and some preferred it done as an inpatient so as to utilise insurance or Medisave funds.
Making a confident diagnosis that allows appropriate pain relief and safer disposal of patients
Several past papers from Western and Japanese settings 1,2,3,4, have shown that CT for abdominal pain changes the leading diagnosis, increases diagnostic certainty, and facilitates management decisions. In haemodynamically stable patients with acute severe and generalized abdominal pain, CTAP is now the preferred imaging test and gives invaluable diagnostic information. Even for unstable patients after adequate resuscitation 5, 6, Paolantonio5 has shown examples of safely diagnosing acute pancreatitis, gastrointestinal perforation, ruptured aneurysm and acute mesenteric ischemia.
In another survey by Kirsch 7 in an American setting, the adult CTAP utilization rate ranged from 11.3% (95% CI 11.2–11.4%) at age 20–29 years to 24.6% (95% CI 24.5–24.8%) for those over 65. The CT utilization rate was 9.3% (95% CI 9.2–9.4%) in EDs with < 20,000 annual visits and increased to 17.8% (95% CI 17.7–17.9%) in EDs with volumes of > 40,000 annual visits.
For our patient population that was discharged from the ED after a negative CTAP, none returned within 72 hours nor had any adverse outcomes. Though analgesic use was not studied, it was generally acknowledged that our emergency physicians and surgeons were more comfortable in allowing the use of opioid analgesics for pain relief in patients undergoing CTAPs.
Effect of early CT on length of hospital stay and need for additional inpatient imaging.
Using appendicitis as a proxy, our results showed benefits for admitted. Our department uses the Alvarado score to help define indications for ED CTAP in the RLQ as part of a suspected appendicitis protocol. It is similar to Sala’s 3 study, which found that the average hospital stay was almost 1 day (22 hours) shorter for patients in the CT group than for those in the control group, but that was statistically not significant. However, in that British study, the CTAPs were done after admission, and not in the ED. Patients in Sala’s CTAP group had significantly fewer additional inpatient radiological investigations.
Mitigating transit time through the ED
There are valid arguments that performing CT scans in the ED could worsen transit time through the ED, causing choke points in the ED. The counter-argument is that with more access block, usage of CT scans could reduce unnecessary admissions and freeing up badly-needed beds. In our hospital, where the daily average bed occupancy often hovers above 95%, we favour the latter argument. To mitigate the CTAP becoming a choke point for patients flowing through the ED, our senior EPs used a system of decision making similar to that described by Wang 8 in Toronto. When studying the flow of ED patients having CTAPs for acute abdomens, they found 3 unique patterns of ED disposition:
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disposition after initial imaging report - the most common pattern is where CTAP is performed and interpreted before the disposition decision (83% of their patients)
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disposition before report – this represents the sequence of events where a disposition decision has been made before the availability of the first radiology report but after the scan has been performed (for instance when the Alvarado score for appendicitis is high enough to warrant admission, and the scan is to differentiate between appendicitis or ovarian abscess and hence admission to surgery or OBGYN)
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disposition before CT – when during the ED visit where the disposition decision was made before the start of the CTAP (for instance when plain films showed obstructed bowel resulting in a decision to admit before a CTAP is ordered)
With adoption of pattern B (7%) and C (6%), the Toronto team found that the ED length of stay (LOS) for pattern A (mean 10.4 hours) is statistically significantly longer than those for pattern B (mean 8.1 hours) and pattern C (mean 6.9 hours). In our study, we did not manage to collect the actual numbers and hours for each pattern, but our EPs practiced the three patterns in a similar way. Our patients’ stay in the ED ranged from 1.37 to 26.83 hours (can be prolonged by access block), with a median of 4.82 hours and mean of 5.2 hours.
Monitoring utilization of CT scans in the ED
With baseline data, it is possible that monitoring of the trends in the usage of CT scans can help avoid abuse and misuse, though it may seem likely that increase usage may be inevitable with time. At the Mayo Clinic, Bellolio 9 performed a cross-sectional study of all ED visits in which a CT scan was obtained between 2003 and 2012 at an academic, tertiary-care setting. Overall, CT use per 1000 ED visits increased from 142.0 in 2003 to 169.2 in 2012 (p < 0.001), while the number of annual ED visits remained stable. The authors found that patients without a primary care provider were more likely to have a CT performed in the ED.
Closer adherence to guidelines and protocols reduces unnecessary CT scans. Gans and co-authors10 (in a multi-specialty Dutch collaboration) aimed to develop an evidence-based guideline for the diagnostic pathway of patients with non-traumatic abdominal pain in the ED. All available international literature on patients with acute abdominal pain was identified and close to 50 were selected. In their guidelines, CTAP leads to the highest sensitivity and specificity in patients with acute abdominal pain, when complemented with thorough history taking and physical findings, supplemented with relevant laboratory investigations and ultrasound.
Understandably, positive CT results are a predictor for hospital admission/transfer, and Modahl 6 found predictive clinical indicators include paediatric age, leucocytosis, and a specified pre-CT diagnosis. Choy and Yoon11 came up with a study to predict negative scans. Three hundred ED patients aged 60 or younger were studied after ED CTAP. Their model predicted that a female patient under 36 years, with a normal white count, and no peritoneal findings on exam is 70.8% less likely to have a significant positive finding on CT than the average patient.
CTAP role in assessing the Geriatric acute abdomen
Older patients often present with vague symptoms, unreliable physical findings, and laboratory values may be altered by chronic organ disease. The morbidity and mortality associated with elderly abdominal pathologic conditions are more significant13. Gardner 12 found in an American retrospective study of 464 patients (> 80 years) that CTAPs were positive in 55%, while ours was 19.6%. Their disease spectrum was similar to ours in the top 10 conditions found. 43% of their diagnoses were clinically unsuspected prior to CT and had a significant influence on clinical management and disposition. A similar conclusion was reached by Millet at al13 in Europe who had 30.3% acute unsuspected pathologies.
Defining clinical indications for ordering CTAPs
Table 1 show that the top six indications are by sites of pain, persistence of abdominal pain despite analgesia, and suspicion for intestinal obstruction. These indications may also be influenced by clinical acumen, scoring systems (for instance the Alvarado score for suspected appendicitis), laboratory results (e.g. hyper-amylasemia), or preliminary imaging (e.g. dilated bowel on plain films).
The approach for ordering CTAPs as guided by quadrant pain aided by relevant investigations is intuitively logical, as well as attractive to a busy ED physician. Pickhardt and Nelson14 studied 1000 patients who had CT scans in the ED. When analysed by quadrant pain, a positive CT diagnosis was provided in 47.3% (473/1000) of all patients, and was highest for LLQ (58.8%) and RLQ (58.0%) symptoms, including diverticulitis and appendicitis in 23.6% and 24.8% cases, respectively. CT positivity was lower for the LUQ (34.4%) and RUQ (38.0%). Lameris15 also studied 11 imaging strategies, and in one strategy driven by location of pain, they found that this approach by location had a sensitivity of 89% and a specificity of 78% for urgent diagnoses.
How much of a negative scan rate is acceptable?
In our study, 16.2% of CTAPs revealed no abnormality to account for the symptoms (259 patients with normal findings, and 43 patients with sepsis and abdominal symptoms but normal CTAP). A negative CTAP is reassuring to both patient and EPs. Medical causes of acute abdominal pain (e.g. diabetic ketoacidosis, dengue) were also confirmed after a surgical abdomen was safely excluded.
When we looked at the literature, we could not find many suitable similar retrospective studies for comparing negative scan rates for CTAPs of the entire abdomen. One comparable study by Pickhardt and Nelson14 had a negative CT diagnosis in 52.7% of all patients. Lameris’ study15 had 183 out of 1021 patients (18%) with a negative scan.
For specific regions, Wertz16 found 15% (7 out of 48 patients) of patients with RUQ pains were negative on CT. For RLQ pains, Woo17 found a negative ED CTAP rate of 60% for 107 patients, while Stengel18 had a negative CT rate of 77% for 2283 patients.