Table 2.

Strength of confidence in quality of quantitative Cohort/Registry studies (Modified STROBE checklist)

Author and year	Variables documented			Bias		Statistical methodology			Descriptive data			Limitations	Score
	Outcome	Exposure	Confounders and modifiers	Documented	Addressed	Full description	Missing Data	Sensitivity analysis	Demographic	Clinical	Social
Aizer, et al, 2012, USA	Yes	Yes	Yes	Yes	No	Yes	No	Yes	Yes	Yes	Yes	Yes	10
Loeb et al, 2013, Sweden	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	11
Filson et al, 2014, USA	Yes	Yes	Yes	Yes	No	Yes	No	No	Yes	Yes	Yes	Yes	9
Hoffman et al, 2014, USA	Yes	Yes	No	Yes	No	Yes	No	Yes	Yes	Yes	Yes	Yes	9
Liu et al, 2015, USA	Yes	No	Yes	Yes	No	Yes	No	No	Yes	Yes	Yes	Yes	8
Maurice et al, 2016, USA	Yes	Yes	Yes	No	No	Yes	No	No	Yes	Yes	Yes	Yes	8
Womble et al, 2014, USA	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	11
Loeb et al, 2016, Sweden	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	11
Loeb et al, 2015, Sweden	Yes	Yes	Yes	Yes	No	Yes	No	No	Yes	Yes	Yes	Yes	9
Hamdy et al, 2016, UK	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes	Yes	No	Yes	10
Bokhorst et al, 2015, Netherlands	Yes	Yes	Yes	No	No	Yes	No	No	No	Yes	No	Yes	6
Weerakoon et al, 2015 Australia.	Yes	Yes	Yes	No	No	Yes	No	Yes	Yes	Yes	No	Yes	8
Parikh et al, 2017, USA	Yes	No	Yes	No	No	Yes	No	Yes	Yes	Yes	Yes	Yes	8
Bokhorst et al, 2016, Worldwide	Yes	Yes	No	No	No	Yes	No	No	No	Yes	No	Yes	5

Notes: variables (clear explanation of all outcomes, exposures, potential confounders and effect modifiers) data source (details given of measurement), study size (≥500 patients), bias (effort made to address potential sources of bias), statistical methodology (description of methods, missing data addressed, sensitivity analysis performed), descriptive data (characteristics of individuals given: demographic, clinical and social) and limitations (generalisability addressed, cautious interpretation).