Table I. Categories, subcategories, and characteristics of Benchmarking Controlled Trials (BCTs).

BCT categories and subcategories	Study objective	Design issues	Causal and effect factors	Implications for
1. Clinical comparison (as determinants for effectiveness and efficiency) Subtypes: 1.1. single or set of intervention(s) 1.2. whole clinical pathway	To assess differences in outcome between health care providers (individual, hospital, district, country) who treat similar patients but their way of treating patients (from single intervention to clinical pathway) potentially differs	1. Between-group differences at baseline must be adjusted for 2. Diagnostics and treatment procedures during the clinical pathway should be properly documented (i) to appraise how plausible the differences in outcome are, and (ii) to make decisions on how to improve treatment of patients	Causal factor: differences in single or sets of interventions or in clinical pathways between the comparator arms Effect factor: differences in all relevant outcomes between the comparator arms	Clinicians, policy-makers
2. System comparisons of the health and social care system (as determinants for effectiveness and efficiency) Subtypes: 2.1. related to the financing of the care system (e.g. tax-based or insurance-based system) 2.2. related to the reimbursement and incentives (e.g. fee for service, bonus for quality) 2.3. related to how and by whom the services are organized/provided (e.g. centralized versus decentralized) 2.4. related to the regulations (e.g. on uptake of new technology) 2.5. related to the available resources for health care (e.g. amount of personnel, GDPs of the countries). 2.6. related to other system or structure-related issues (e.g. freedom of choice)	To assess differences in outcome between health care providers due to reasons related to the health and social care system	1. Between-group differences at baseline must be adjusted for 2. Diagnostic and treatment procedures during the clinical pathway should be properly documented and analyzed as mediators of effectiveness	Causal factor: differences in features related to the health care system or part of it Effect factor: differences in all relevant outcomes between the comparator arms: clinical effects and effects on the health care system itself	Policy-makers