Criteria for a judgment of yes for the sources of risk of bias

Method of randomization

Item has a positive score if the concealment of treatment allocation is explicitly described to provide assurance of adequate concealment. Examples of adequate concealment procedures are some form of centralized randomization scheme, numbered or coded containers, an on‐site computer system providing allocations in a locked, unreadable file that can be assessed only after inputting the characteristics of an enrolled participant, and sequentially numbered, sealed, opaque envelopes. Clearly inadequate procedures are alternation, or reference to case record numbers, dates of birth, day of the week or any other such approach.

Concealment of treatment allocation

Item has a positive score if the procedure of sequence generation is explicitly described and adequate. Examples are random‐number tables, computer random‐number generator, and coin tossing.

Blinding of patients

Item has a positive score if patients are blinded regarding treatment allocation and the method of blinding is appropriate. As it is difficult to blind patients for behavioral therapy, the credibility of the treatments should be evaluated and treatments should be equally credible and acceptable to patients.

Blinding of care providers

Item has a positive score if the care provider is blinded regarding regarding treatment allocation.

Blinding of outcome assessment

Item has a positive score if the outcome assessors are blinded regarding treatment allocation and the blinding is evaluated and adequate. If only self‐reported (by the patients) outcome measures are used and no outcomes were measured by a blinded observer, item 3) will be scored negative.

Drop‐out rate during the intervention period

Item has a positive score if participants who were included in the study but did not complete the observation period or were not included in the analysis are described. Item 2) is also positive if the drop‐out rate (that is the number of randomized patients minus the number of patients at the main moment of effect measurement divided by all randomized patients and multiplied by 100) is less than 20%.

Intention‐to‐treat analysis

Item has a positive score if all randomized patients are reported/analyzed for the most important moments of effect measurement irrespective of non‐compliance and co‐interventions.

Withdrawals during follow‐up

Item has a positive score if participants who were included in the study but did not complete the observation period or were not included in the analysis are described. Item 2) is also positive if the drop‐out rate (that is the number of randomized patients minus the number of patients at the main moment of effect measurement divided by all randomized patients and multiplied by 100) is less than 30%.

Similarity of baseline characteristics

Item has a positive score if the study groups are comparable at baseline for the most important prognostic factors (for example, duration of complaints, value of outcome measures, age, recurrence status, and absence or presence of radiation). The blinded reviewers decide if the groups are similar.

Co‐interventions avoided or equal

item has a positive score if co‐interventions are avoided in the study design or are equally divided among the intervention groups.

Compliance

Item has a positive score if adherence to the interventions is acceptable. The blinded reviewers decide whether adherence to the interventions is acceptable, based on the reported intensity, duration, number and frequency of sessions for both the index and control interventions.

Adequate length of follow‐up

Item has a positive score if the duration of follow‐up is 12 months or more.