DIAgnostic iMaging or Observation in early equivocal appeNDicitis (DIAMOND): open-label, randomized clinical trial

Mild appendicitis may resolve spontaneously. The use of CT may lead to an overdiagnosis of uncomplicated appendicitis. The aims of this study were to examine whether early imaging results in more patients being diagnosed with acute appendicitis than initial observation, and to study the safety and feasibility of score-based observation compared with imaging in patients with equivocal signs of appendicitis.

Patients with suspected appendicitis with symptoms for fewer than 24 h and an Adult Appendicitis Score of 11-15 were eligible for this trial. After exclusions, patients were randomized openly into two equal-sized groups: imaging and observation. Patients in the imaging group had ultrasound imaging followed by CT when necessary, whereas those in the observation group were reassessed after 6-8 h with repeated scoring and managed accordingly. The primary outcome was the number of patients requiring treatment for acute appendicitis within 30 days.

Ninety-three patients were randomized to imaging and 92 to observation; after exclusions, 93 and 88 patients respectively were analysed. In the imaging group, more patients underwent treatment for acute appendicitis than in the observation group: 72 versus 57 per cent (difference 15 (95 per cent c.i. 1 to 29) per cent). This suggests that patients with spontaneously resolving appendicitis were not diagnosed or treated in the observation group. Some 55 per cent of patients in the observation group did not need diagnostic imaging within 30 days after randomization. There was no difference in the number of patients diagnosed with complicated appendicitis (4 versus 2 per cent) or negative appendicectomies (1 versus 1 per cent) in the imaging and observation groups.

Score-based observation of patients with early equivocal appendicitis results in fewer patients requiring treatment for appendicitis. Registration number: NCT02742402 (http://www.clinicaltrials.gov).