Evaluation of clinical examination and preoperative imaging in patients with right iliac fossa pain and a medium or high risk score for appendicitis (RIFT-2)

Introduction: Clinical risk models can be used to identify UK patients with right iliac fosa pain who are at low-risk of appendicitis and can be safely managed on ambulatory pathways, avoiding hospital admission and unnecessary surgery. This study examined the diagnostic pathways in patients with medium or high-risk scores. Methods: This prospective cohort study included patients admitted with suspected appendicitis in the UK. Patients aged ≥16 years were included if they had a medium or high-risk score for appendicitis (Appendicitis Inflammatory Response Score (AIRS) >2 in men, Adult Appendicitis Score (AAS) >8 in women). The primary outcome measure was the normal appendicectomy rate (NAR). The AIRS and AAS risk prediction models were validated against pre-determined criteria. Results: This UK study included 2,231 women and 1,958 men. Overall, 57.7% of patients underwent surgery. The NAR was 18.4% in women aged 16-45 years, 9.5% in men aged 16- 45 years, 4.5% in women aged ≥46 years, and 2.1% in men aged ≥46 years. Risk prediction models did not achieve the pre-determined threshold to be used to identify patients with appendicitis. Ultrasound was the most common imaging modality in women aged 16-45 years, whereas CT was most common in the other subgroups. CT was performed in 12.8% of women aged 16-45 years, 21.1% in men aged 16-45 years, 69.3% in women aged ≥46 years, and 74.5% in men aged ≥46 years. The overall NAR in patients who had CT imaging alone (3.6%) was lower than in patients who had no imaging (12.4%) or ultrasound imaging alone (19.0%). Conclusion: UK patients with a low-risk of appendicitis should be triaged to ambulatory management, whilst those with a medium/high-risk should mostly undergo a CT scan. Normal appendicectomy should become a specific therapeutic option rather than a chance finding.