Table 3.

Characteristics of included articles.

Characteristics of included articles		Number of articles
Study design	Primary studies – randomized studies – non‐randomized studies	103 81 22
	Reviews – systematic reviews – scoping reviews	97 77 20
Publication status	Completed On‐going Conference abstracts	78 primary studies/92 reviews 21 primary studies/4 reviews 4 primary studies/1 review
Intervention focus	Social isolation Loneliness Both social isolation and loneliness	34 primary studies/54 reviews 41 primary studies/23 reviews 34 primary studies/54 reviews
Intervention format	One‐on‐on Group‐based One‐on‐one and group based Unspecified	29 primary studies/10 reviews 56 primary studies/23 reviews 11 primary studies/28 reviews 7 primary studies/26 reviews
Intervention strategies to reduce social isolation and loneliness	Social cognitive training Improving social skills Enhancing social interactions Enhancing social support Multicomponent	21 primary studies/19 reviews 37 primary studies/40 reviews 30 primary studies/58 reviews 49 primary studies/81 reviews 16 primary studies/3 reviews
Outcomes	Individual level outcomes Community level outcomes Process indicators	95 primary studies/96 reviews 40 primary studies/40 reviews 28 primary studies/31 reviews
Most reported population sociodemographic characteristics	Gender/sex Age range (70–80 years old) Education Health condition (dementia)	83 primary studies/78 reviews 78 primary studies/55 reviews 50 primary studies/6 reviews 16 primary studies/30 reviews
Settings	Personal home Long‐term care (nursing homes) Independent living (residential homes) Assisted living	36 primary studies/45 reviews 22 primary studies/45 reviews 12 primary studies/23 reviews 5 primary studies/10 reviews
Most common locations for included studies	USA The Netherlands UK Canada Australia	42 primary studies/44 reviews 8 primary studies/25 reviews 6 primary studies/22 reviews 6 primary studies/16 reviews 5 primary studies/22 reviews