A micro costing analysis of the development of a primary care intervention to improve the uptake of diabetic retinopathy screening.

Our results highlight that intervention development requires a significant amount of human capital input, combining research experience, patient and public experience, and expert knowledge in relevant fields. The time committed to intervention development is critical but has a significant opportunity cost. With limited resources for research on developing and implementing interventions, capturing intervention development costs and incorporating them as part of assessment of cost-effective interventions, could inform research priority and resource allocation decisions.