Table 3.

Quality assessment and risk of bias^a

Eligible Studies	Risk of bias domains — ROBINS-I
Eligible Studies	Bias due to confounding	Bias in selection of participants into the study	Bias in classification of interventions	Bias due to deviations from intended interventions	Bias due to missing data	Bias in measurement of outcomes	Bias in the selection of the reported result	Overall risk of bias
Singer, 2015¹⁰	Moderate	Moderate	Low	Low	NI	Low	Low	Moderate
Singer, 2014¹¹	Moderate	Moderate	Low	Low	NI	Low	Low	Moderate
Larsen, 2011¹²	Moderate	Moderate	Low	Serious	NI	Moderate	Moderate	Moderate
Mullen, 2014¹³	Serious	Serious	Moderate	Low	NI	Moderate	Moderate	Serious
Maung, 2014¹⁴	Serious	Serious	Moderate	Low	NI	Moderate	Moderate	Serious
Choong, 2014¹⁵	Serious	Serious	Moderate	Low	NI	Moderate	Moderate	Serious
Smith, 2010¹⁶	Serious	Serious	Moderate	Low	NI	Moderate	Moderate	Serious
Varpula, 2007¹⁷	Serious	Serious	Moderate	Serious	NI	Moderate	Serious	Serious

↵a Low — comparable with a well-performed RCT. Moderate — sound for a non-randomised study but not comparable with a well-performed RCT. Serious — important problems in this domain. Critical — too problematic to provide any useful evidence on the effects of the intervention. NI = no information. RCT = randomised controlled trial.