Background
Acute appendicitis is one of the most common indications for emergency abdominal surgery [
1]. Computed tomography (CT) has assumed a paramount position in the disposition of adult patients with suspected appendicitis in the developed world, owing to its many advantages over other diagnostic tests including ultrasonography [
2,
3]. Studies conducted in Korea (Park JH on behalf of the LOCAT group: Diagnostic imaging utilization in cases of acute appendicitis: multi-center experience, unpublished) and the United States [
4‐
6] have reported preoperative CT utilization rates ranging from 93% to 98% in patients undergoing appendectomy between 2007 and 2011. CT is highly accurate, readily available, rapid, easy to perform and interpret, and rarely affected by bowel gas, severe abdominal pain or extreme body habitus [
7]. Despite a historical debate [
8], a number of recent studies [
5,
6,
9‐
12] have consistently shown that the increased use of CT coincides with a reduction in the negative appendectomy rate (NAR) without an increase in the appendiceal perforation rate (APR). NAR is the percentage of the number of negative appendectomies (removal of an uninflamed appendix) out of all non-incidental appendectomies [
6,
8‐
12]. NAR and APR are two important reciprocal measures of the quality of care, indicative of false-positive and delayed (false-negative) diagnoses, respectively. The routine use of CT for patients suspected of having appendicitis has also been reported to be cost-effective through prevention of delayed or inaccurate diagnoses [
13].
There has been a surge in CT use for diagnosing appendicitis during the last decade in the United States [
5,
6,
8‐
12], indicating that the threshold for the decision to use CT may have declined. Over 250,000 appendectomies are performed in the United States each year [
1], while approximately 95,000 were performed in the Republic of Korea in 2011 [
14]. The vast majority of these patients undergo CT examination preoperatively [
5,
6,
9,
11,
12]. Moreover, there is an even greater number of patients who undergo CT and do not finally undergo appendectomy. Factors contributing to these trends include improved CT technology, widespread availability, favorable reimbursement and a general shift in the culture of medicine toward defensive medicine [
15] and dependency on imaging tests [
16].
Many patients with suspected appendicitis are children or young adults [
1], for whom CT radiation is of particular concern [
17]. Although debatable, there are increasing concerns that even a single typical abdomen CT examination may increase the risk of carcinogenesis [
17‐
19]. While such risk induced by an individual CT scan would be minute, multiplication by the large number of exposures may imply the real occurrence of cancer. With a greater awareness of the carcinogenic risk [
19,
20], it may no longer be certain if the benefits of CT in diagnosing appendicitis clearly outweigh the risk associated with the radiation doses traditionally used. It should be noted that the traditional radiation doses have historically been determined without robust scientific basis [
21], with large variations in practice across hospitals [
22]. Furthermore, while there is no rationale for using an identical dose for young appendicitis patients and elderly patients with malignancies, attempts have rarely been made to properly differentiate the dose levels according to the application.
Results from several studies have suggested that reducing the radiation dose by 50% to 80% does not significantly impair the diagnosis of appendicitis [
23‐
25], although the dose reduction decreases image quality. Recently, a single-institution randomized controlled trial [
26] demonstrated the non-inferiority of low-dose (LD) CT, which used a quarter of the standard dose (SD), compared to SD CT with respect to NAR (3.5% vs 3.2%; 95% CI for the difference, -3.8 to 4.6 percentage points) for adolescents and young adults with suspected appendicitis. However, the study had a potentially important limitation. While appendicitis is a very common disease encountered across emergency departments worldwide, it remains uncertain if the results of that particular study can be generalized to other institutions that are less experienced in using LD CT. At the time of writing, the LD CT technique has not been widely accepted as the standard of practice in many institutions. We have therefore proposed a multi-institution trial with a similar study design to confirm the generalizability of the results of the previous single-institution study. In this article, we summarize the protocol of the study, LOCAT (low-dose CT for appendicitis trial).
Study objectives
The primary objective of LOCAT is to determine whether LD CT is non-inferior to SD CT as the first-line imaging test in regard to NAR for adolescents and young adults. In addition, LOCAT aims to disseminate the use of the LD CT technique throughout the participating sites through the implementation of the study protocol.
Acknowledgements
LOCAT is funded by the Korea Healthcare Technology R&D Project, Ministry of Health and Welfare, Republic of Korea (HI13C00040200), the Medical Research Collaborating Center, Seoul National University Bundang Hospital (02-2013-091) and Dasol Life Science Inc (06-2013-107), all of which have no role other than funding. LOCAT is supported by Korean Society of Abdominal Radiology and Korean Society of Radiology Center for Clinical Research.
LOCAT is a collaborative effort by the LOCAT Group:
1. Soyeon Ahn, Seoul National University Bundang Hospital
2. Sang Hoon Cha, Korea University Ansan Hospital
3. Han Jin Cho, Korea University Ansan Hospital
4. Jea Min Cho, Seoul National University
5. Seong Whi Cho, Kangwon National University Hospital
6. Pil Cho Choi, Kangbuk Samsung Medical Center
7. Sung Hyuk Choi, Korea University Guro Hospital
8. Yoo Shin Choi, Chung-Ang University Hospital
9. Yong Hwan Chung, Seoul National University Bundang Hospital
10. Bon Seung Gu, Seoul National University Bundang Hospital
11. Young Rock Ha, Daejin Medical Center, Bundang Jesaeng General Hospital
12. Sang Kuk Han, Kangbuk Samsung Medical Center
13. Jae Yeon Heo, LOCAT Office Staff
14. Seong Sook Hong, Soonchunhyang University Hospital
15. Suk Ki Jang, Daejin Medical Center, Bundang Jesaeng General Hospital
16. Sung-Bum Kang, Seoul National University Bundang Hospital
17. Bohyoung Kim, Seoul National University Bundang Hospital
18. Cho Hee Kim, LOCAT Office Staff
19. Ho Jung Kim, Soonchunhyang University Bucheon Hospital
20. Hyuk Jung Kim, Daejin Medical Center Bundang Jesaeng General Hospital
21. Joong Hee Kim, Seoul National University Bundang Hospital
22. Kwang Pyo Kim, Kyung Hee University
23. Kyuseok Kim, Seoul National University Bundang Hospital
24. Mi Kyung Kim, Chung-Ang University Hospital
25. Mi Sung Kim, Kangbuk Samsung Medical Center
26. Min-Jeong Kim, Hallym University Sacred Heart Hospital
27. Sung Eun Kim, Chung-Ang University Hospital
28. Young Chul Kim, Ajou University Hospital
29. Young Hoon Kim, Seoul National University Bundang Hospital
30. Yousun Ko, Seoul National University Bundang Hospital
31. Heon-Ju Kwon, Kangbuk Samsung Medical Center
32. Chang Hee Lee, Korea University Guro Hospital
33. Hae Kyung Lee, Soonchunhyang University Bucheon Hospital
34. Hye Seung Lee, Seoul National University Bundang Hospital
35. Jae Hyuk Lee, Seoul National University Bundang Hospital
36. Ji Eun Lee, LOCAT Office Staff
37. Jongmee Lee, Korea University Guro Hospital
38. Kyoung Ho Lee, Seoul National University Bundang Hospital
39. Min Hee Lee, Soonchunhyang University Bucheon Hospital
40. Min Jung Lee, LOCAT Office Staff
41. Yoon Jin Lee, Seoul National University Bundang Hospital
42. Ri Young Na, LOCAT Office Staff
43. Chan Jong Park, Seoul National University Bundang Hospital
44. Chul Woo Park, Kangwon National University Hospital
45. Ji Hoon Park, Seoul National University Bundang Hospital
46. Sung Bin Park, Chung-Ang University Hospital
47. Yang Shin Park, Korea University Guro Hospital
48. Dong Hyuk Shin, Kangbuk Samsung Medical Center
49. Eun Jung Shin, LOCAT Office Staff
50. Hyun Sik Woo, SMG-SNU Boramae Medical Center
51. Ji Young Woo, Hallym University Kangnam Sacred Heart Hospital
52. Hyun Kyung Yang, Seoul National University Bundang Hospital
53. Suk Keu Yeom, Korea University Ansan Hospital
54. Boem Ha Yi, Soonchunhyang University Bucheon Hospital