Researchers from Israel have developed a new scoring system to help decide about the need to do an abdominal pelvic computed tomography (APCT) in patients with Crohn’s disease, who present to the Emergency Department with acute gastrointestinal complaints. Their findings are reported in a retrospective study published in the Journal of Clinical Gastroenterology.¹

The study included 183 adult patients (mean age, 36 years) with known Crohn’s disease who underwent APCT in the ED. Data was obtained between January 2005 and January 2018. Men comprised 61% of the study population.

Different parameters such as the patients’ characteristics, ED complaints, disease history and lab tests, which included both positive and negative findings, were compared to devise a new scoring system that could predict urgent findings on APCT and thus reduce the need for APCT in these patients. These urgent findings were defined as OPAN (obstruction, perforation, abscess or non–CD-related urgent findings].

The score was named the CATCH (Crohn Assessment Tool for CT upon Hospitalization) Score and used seven parameters to calculate it: ED complaint of diarrhea, ED complaint of fever on arrival, smoker, ileocolic  disease at diagnosis, ED neutrophils > 75% on differential white blood cell (WBC) count, ED platelets in complete blood count (CBC) > 350x10⁹/L and ED C-reactive protein (CRP) > 50 mg/L.

Each variable was scored as either +/- 1 (according to the direction of effect) or 0 (if the answer is no or unknown). A score of ≥1 as the cut-off value for ED APCT had a sensitivity of 85%, a specificity of 57%, a negative predictive value (NPV) of nearly 83% and a positive predictive value (PPV) of 61% for significant findings on APCT.

The mean number of APCTs done was 4.1. Eighty-one (44%) patients had significant findings on APCT, the most common being small intestinal obstruction seen in 33 patients (41%). However, only 18 of the 81 patients (22%) with significant findings underwent invasive intervention (interventional CT and surgery) during their hospital stay; all other patients were managed conservatively. This implies that physicians treating these patients preferred to manage them conservatively, particularly during the active inflammatory stage.

When the CATCH score was used in the study population, all 18 patients who had an intervention (100%) scored ≥ 1 compared to 95% patients (57.6%) who scored ≥1 in the no intervention group. The sensitivity of the new score for intervention was 100% with a specificity of 42.4% (PPV: 15.9% and NPV: 100%). According to the researchers, using this score could have avoided the use of APCT in 70 patients (42%).

Platelet count >350×10⁹/L, CRP >50 mg/L, neutrophil count >75% and ileocolon location at the time of diagnosis were all found to be positive predicting factors, while ED complaints of diarrhea/fever or smoking decreased the odds for significant findings on APCT scan.

Some patients in the study group were found to have undergone 22 APCTs since their diagnosis was revealed during history taking. This study has demonstrated the utility and the high NPV of the new scoring system in precluding the need for APCT by predicting findings that could necessitate invasive intervention. It is a simple and easy-to-calculate score based on seven clinical and laboratory parameters that are routinely done and hence are readily available.

Hence, the new CATCH score can come to the aid of the physicians in the ED to help them decide about the emergent need for an APCT and reduce unwarranted scans. “This can provide time for further thorough evaluation of these patients, preferably with consultation of a gastrointestinal specialist, resulting in a better patient tailored therapeutic plan,” state the study authors. However, they do recommend more studies to further corroborate the predictive ability of the score as well as the cut-off values.

Reference

1. Riskin Geuz KS, et al. Less emergency department abdominopelvic computed tomography for patients with Crohns disease: a new scoring system. J Clin Gastroenterol. 2021 Dec 15. doi: 10.1097/MCG.0000000000001634.