Selection bias and power

Study	Study design	Q21: Same population	Q22: Participants recruited at the same time	Q26: Loss of follow up reported?	Total score / 19
Maron et al [29]	Cross sectional	Yes	Yes	No	14
Corrado et al [30]	Cohort	Yes	Yes	U	17
Fuller et al [31]	Cohort	Yes	Yes	Yes	15
Pelliccia et al [32]	Cross sectional	Yes	Yes	No	15
Basso et al [33]	Case review	Yes	Yes	No	17
Baggish et al [34]	Cross sectional	Yes	Yes	No	17
Hevia et al [35]	Cross sectional	Yes	No	No	15
Magalski et al [36]	Cohort	Yes	No	U	15
Bessem et al [37]	Cross sectional	Yes	No	No	16
Sofi et al [38]	Cross sectional	Yes	Yes	No	18
Tanaka et al [39]	Cross sectional	Yes	Yes	Yes	14
Marek et al [40]	Cohort study	Yes	Yes	U	16
Steinvil et al [41]	Cohort study	Yes	Yes	U	8
Wilson et al [42]	Cross sectional	Yes	Yes	No	15
Pelliccia et al [43]	Cross sectional	Yes	Yes	No	15
Le et al [44]	Cross sectional	Yes	Yes	Yes	18

Score of all questions Yes= 1, No = 0; U: Unable to determine