Twenty papers were included in this review (n=more than 3,588): 10 observational/descriptive studies; six non-randomised studies; and four RCTs.
Observational/descriptive studies: Five papers were quantitative, three qualitative and two used mixed methods. Overall research quality was judged to be poor to fair and the mean quality rating was 4.8 (range 0 to 8 out of 13). All but one study appeared to report beneficial effects for both patients and volunteers.
Non-randomised studies: All six papers reported quantitative data and compared participation in a volunteer program versus non-participation. Five studies were retrospective. Overall quality was scored as fair. Mean score was 7.7 (range 6 to 9).
RCTs: All four RCTs presented quantitative data; one also incorporating a qualitative component. The mean quality rating was 9.8 (range 7 to 13). All met Cochrane review inclusion criteria.
Overall, the synthesis reported that most volunteer-based support programs were well received. Their impacts included improved well-being and reduced anxiety; however, only one well-designed RCT reported a significant immediate improvement for the intervention group.