Table 3.

Assessment of risk of bias within the studies.

	Risk of selection bias		Risk of performance bias	Risk of detection bias	Risk of attrition bias	Risk of reporting bias
References	Random sequence generation	Allocation concealment	Blinding of participants and researchers	Blinding of outcome assessment	Incomplete outcome data	Selective reporting
Rothbaum et al., 2000	Unclear	Unclear	Unclear	Unclear	Low	Low
Emmelkamp et al., 2002	Unclear	Unclear	Unclear	Unclear	Low	Low
Rothbaum et al., 2006	Unclear	Unclear	Unclear	Unclear	Unclear	Low
Michaliszyn et al., 2010	Unclear	Unclear	Unclear	Unclear	High	Low
Anderson et al., 2013	Low	Low	Unclear	Unclear	Unclear	Low
Kampmann et al., 2016	Low	Low	Unclear	Low	Unclear	Low
Bouchard et al., 2016	Low	Low	Unclear	Unclear	Low	Low
Botella et al., 2007	Unclear	Unclear	Low	Low	Low	Low
Meyerbroeker et al., 2013	Unclear	Unclear	Unclear	Unclear	Low	Low

Risk of bias was assessed using a tool from the Cochrane Collaboration (Higgins et al., 2011). Risk of bias was rated as low, unclear, or high.