Box 1.

Summary of exemplar studies

Study	Condition	Aims
Schrag et al (2015)10	Parkinson’s disease	‘Assess the association between several prediagnostic features and a subsequent diagnosis of Parkinson’s disease, and chart the timeline of these presentations before diagnosis.’
Blackwell et al (2021)11	Inflammatory bowel disease (IBD)	‘Examine the prevalence of gastrointestinal symptoms attributable to undiagnosed IBD before diagnosis and … identify predictors for timely specialist review.’
Miller et al (2021)12	Tuberculosis	‘Propose a population-based approach for estimating the incidence and duration of diagnostic delays associated with tuberculosis, and … describe the risk factors associated with patients experiencing a diagnostic delay.’
Miller et al (2021)13	Herpes simplex encephalitis (HSE)	‘Determine the incidence of diagnostic delays for HSE … identify risk factors and outcomes associated with diagnostic delays.’