Table 3.

Data to be extracted from each study

Category	Parameter to extract
Descriptive characteristics of the study	• Location of the study
	• Study design
Type of sample, source and outcome	• Environmental media or biological sample type tested
	• Location of the WWTP where the sample(s) was (were) taken
	• Quantity of samples
	• Bacterial species and/or genes analyzed
	• Microbiological method used
Type of exposure	• Categorical: Downstream, downwind or down-gradient
	• Continuous: Distance to the WWTP; distance to the Comparator
Type of comparator	• Categorical: Upstream, upwind or up-gradient
	• Continuous: Distance to the WWTP; distance to the exposure site?
Sample size	• If exposure is categorical: Sample size of each group
	• If exposure is continuous: Total sample size
If statistical modelling was used	• Type of model
	• Effect measure (extracted or computed if there is enough raw data reported)
	• Measure of variability
	• p value
Confounding control	• Methods to account for confounding or account for clustering data
Measure of resistance	• Proportional: Is denominator present? Was the denominator stable across sampling sites?
	• Absolute