Table 2.

Examples of performance metrics within each identified category

Categories	Example performance metric	Studies in which metric included
Assessing site potential	Site location potential index based on an assessment of the number of patients at an individual site with the disease of interest	[14]
Monitoring recruitment	Number of participants randomised per site	[15, 17, 27]
Monitoring retention	Rates of withdrawal by site	[20, 25]
Quality of data collection	Number of data queries per participant	[2, 12, 19]
Trial conduct	Protocol violations per site or per participant	[12, 15, 23, 27, 30]
Trial safety	Serious adverse event (SAE) reporting per site	[11, 24, 27]