Table 3.

Study Characteristics

Variable	Number of studies (%)
Length of peer support contact
Less than 1 month	20 (20.0)
Between 1 month and less than 6 months	16(16.0)
Greater than 6 months	17(17.0)
Not reported or unclear	47 (47.0)
Study Design
Randomized Controlled Trial	26 (26.0)
Cluster-randomized Randomized Controlled Trial	6 (6.0)
Quasi-experimental	9 (9.0)
Other controlled triala	2 (2.0)
Single group pre-post	19(19.0)
Descriptive or observational	30 (30.0)
Otherb	4 (4.0)
Not reported	4 (4.0)
Study Funding
Federal	37 (37.0)
Private (state or regional foundation)	4 (4.0)
Private (national foundation)	12(12.0)
State / local government	4 (4.0)
Pharmaceutical	0(0)
Other	3 (3.0)
Multiple c	27 (27.0)
Not reported	13 (13.0)
Study Outcomes
Recipient engagement in clinical care	43 (43.0)
Behavioral risk	2 (2.0)
Quality of life	0(0)
Mental health	0(0)
Other psychosocial outcomes d	8 (8.0)
Cancer progression and other clinical outcomes	0(0)
Othere	4 (4.0)
Multiple f	40 (40.0)
Not reported	3 (43.0)

^aExamples: “Cluster-randomized at clinic level, randomized at individual level” and “group-randomized trial with nested cohort design”

^bExamples: “Simulation” or “multiple types of study designs”

^cThe most common type of funding combination was federal and private (n=11, 11% of all studies).

^dExamples: appraisal, self-efficacy, social support, attitudes, optimism, intentions, knowledge)

^eExamples: “cost”, “feasibility or process evaluation outcomes”, “sexual function”, etc.

^fThe most common type of combination was recipient engagement in clinical care and psychosocial outcomes (n=16, 16% of all studies).