Co‐Design of a Theory‐Informed, Multicomponent, Intervention for Diagnostic Stewardship in a Major‐Referral Emergency Department: A Qualitative Descriptive Study

ABSTRACT Objective Low‐value diagnostic tests harm patients. Stewardship of tests can improve patient safety. Co‐design and behavioural change theories can enhance the effectiveness of diagnostic stewardship interventions. This study aimed to co‐design a theory‐informed diagnostic stewardship intervention at a major‐referral emergency department in Queensland, Australia. Methods A qualitative study was conducted at Townsville University Hospital Emergency Department. The Theoretical Domains Framework underpinned intervention design. Emergency clinicians ordering pathology tests were eligible for inclusion. A purposive sample of consenting participants was recruited. Data were collected via workshops facilitated by the lead author. Conversations were audio recorded and digitally transcribed. Data were managed with NVivo. Data were analysed by inductive and deductive approaches to generate codes, categories and themes. Thematic saturation and optimal stakeholder engagement influenced the final sample size. Trustworthiness was ensured via reflexivity, audit trail, thick description and participant validation. Results Seven workshops were conducted with 35 emergency physicians (18 male, 17 female) with a range of specialist experience (1–31 years). Urine culture was the diagnostic test of choice. Culture, complexity, and efficiency were identified as the major drivers of low‐value urine cultures. Education, nudge, clinical champions, and audit/feedback were selected as intervention components. Credibility of change and workflow inefficiency were perceived as intervention challenges. Conclusion Stakeholder engagement has enhanced perceived acceptability of this co‐designed intervention for urine culture diagnostic stewardship. Behavioural change theories strengthen co‐designed interventions by addressing context‐specific drivers of low‐value tests. Co‐design and behavioural change theories can inform bespoke interventions to nurture a culture of diagnostic stewardship in emergency medicine practice.