Researchers examined the efficacy of existing risk prediction models in identifying patients presenting to hospitals in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. They investigated all existing appendicitis risk prediction models via performing a systematic search and determined their validation using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF from March to June 2017. They identified about 5,345 patients across 154 UK hospitals, of which two-thirds (3,613 of 5,345, 67·6%) were women. This indicates a disproportionate risk of admission among women in the UK without surgical intervention; these women had high rates of normal appendicectomy. Fifteen validated risk prediction models were identified; of these, the Adult Appendicitis Score performed best (cut-off score 8 or less, specificity 63·1%, failure rate 3·7%). For men, the best performance of the Appendicitis Inflammatory Response Score was reported (cut-off score 2 or less, specificity 24·7%, failure rate 2·4%).