“…Two studies used a mixed-methods approach [25,32], three utilized a qualitative approach [28][29][30] and 12 used a quantitative approach [19][20][21][22][23][24]26,27,31,[33][34][35]. Within each broad methodological approach, various specific methods were employed: one study undertook a scoping review and focus group method [30], two studies analysed call logs and call assessment checklists [21,24], four studies used semi-structured interviews [25,28,29,32] and 12 studies utilized questionnaires [19,20,22,23,[25][26][27][31][32][33][34][35]. Of the studies using questionnaires, nine studies specifically measured loneliness or social isolation, using a version of the UCLA loneliness scale self-report scale [20,22,26,27,33,35], the leave behind questionnaire [31], the loneliness scale [19] and the Lubben social network scale …”