Table 2.

Criteria of the assessment of study quality.

In Cuijpers et al. (2010, p. 212, 213)	In this meta-analysis
(1) “Participants met diagnostic criteria for a depressive disorder (as assessed with a personal diagnostic interview, such as CIDI, SCID, or SADS, and using a diagnostic system such as DSM or Research Diagnostic Criteria)”	(1) Breast cancer patients or breast cancer survivors
(2) “The study referred to the use of a treatment manual (either a published manual, or a manual specifically designed for the study)”	(2) Detailed description of the psychological approach, timing, procedure, and sessions
(3) “The therapists who conducted the therapy were trained for the specific therapy, either specifically for that study or as a general training”	(3) The psychologists who conducted the psychological treatment were trained for the specific psychological intervention
(4) “Treatment integrity was checked during the study (by supervision of the therapists during treatment or by recording of treatment sessions or by systematic screening of protocol adherence by a standardized measurement instrument)”	(4) “Treatment integrity was checked during the study (by supervision of the psychologists during treatment or by recording of treatment sessions or by systematic screening of protocol adherence by a standardized measurement instrument)”
(5) “Data were analyzed with intention-to-treat analyses, in which all persons who were randomized to the treatment and control conditions initially were included in the analyses”	(5) Same
(6) “The study had a minimal level of statistical power to find significant effects of the treatment, and included ≥ 50 persons in the comparison between treatment and control groups [this allows the study to find standardized effect sizes of d = 0.80 and larger, assuming a statistical power of 0.80 and α = 0.05; calculations in Stata (Stata Corp., USA)]”	(6) Not included
(7) “The study reported that randomization was conducted by an independent (third) party (this variable was positive if an independent person did the randomization, when a computer program was used to assign patients and survivors to conditions, or when sealed envelopes were used)”	(7) Same
(8) “Assessors of outcome were blinded and did not know to which condition the respondents were assigned to (this was only coded when the effect sizes were based on interviewer-based depression ratings; when only self-reports were used, it was assumed that this criterion was met)”	(8) Same
	Additional items to further explore the quality of studies
	(9) The control groups do not receive an intervention*
	(10) The absence of differential attritions between intervention and control groups (e.g., a great number of participants dropped out of the research study)*
	(11) The absence of reporting bias in the results*

^*Items included in this meta-analysis to further explore the quality of studies.