A systematic survey of demographic representation in anaesthesia randomised controlled trials
Comparing five years of randomised trials from anaesthesia's leading journals against the NAP7 national activity survey to quantify who is missing from the evidence base.
Trial populations differ systematically from the patients seen in routine care. Older people, those living with significant comorbid disease or obesity, and patients presenting as an emergency are consistently excluded or under-recruited, while women and minority ethnic groups remain underrepresented across medicine more broadly. No study has yet examined whether this pattern holds in anaesthesia specifically, or how large the gap is between the patients enrolled in anaesthesia trials and those who actually receive anaesthetic care in the UK.
We are systematically screening every randomised controlled trial published in Anaesthesia, the British Journal of Anaesthesia, Anesthesiology and the European Journal of Anaesthesiology between 2021 and 2025, extracting eligibility criteria and reported participant demographics for each. These trial populations are compared against NAP7, the most detailed prospective survey of UK anaesthetic activity available, covering over 24,000 anaesthetic episodes across more than 200 NHS hospitals. By calculating participation-to-prevalence ratios for age, sex, ASA grade, BMI and surgical urgency, the survey will produce a quantified account of representation gaps in the anaesthesia trial evidence base, developing an understanding of how far existing evidence can safely be extrapolated to the patients anaesthetists treat every day.