Table 1.

Description of the included studies.

No.	Reference	Journal	Type of study	Country	Type of social mediaa	Attitudeb
1	Abdul, 2011 [38]	Lancet	Correspondence	Taiwan	Facebook	+
2	Adams, 2010 [25]	Int J Med Inf	Review	Netherlands	Social media in general	+/–
3	Adams, 2011 [26]	Soc Sci Med	Original	United States, United Kingdom, Netherlands	Rating sites	+/–
4	Bacon, 2009 [39]	BMJ	Opinion paper	United Kingdom	Rating sites	+
5	Bardach, 2012 [40]	BMJ Qual Saf	Original	United States	Rating sites	+
6	Black, 2009 [41]	Inform Prim Care	Original	United States	Rating sites	+/–
7	Denecke, 2013 [42]	Methods Inf Med	Editorial	n/a	Social media in general	+/–
8	Emmert, 2012 [27]	Methods Inf Med	Original	Germany	Rating sites	+/–
9	Emmert, 2013 [43]	J Med Internet Res	Review	n/a	Rating sites	+/–
10	Galizzi, 2012 [44]	BMJ Open	Original	United Kingdom	Rating sites	+/–
11	Gao, 2012 [15]	J Med Internet Res	Original	United States	Rating sites	+/–
12	Greaves, 2012c[28]	BMJ Qual Saf	Original	United Kingdom	Rating sites	+
13	Greaves, 2012 [29]	Arch Intern Med	Original	United Kingdom	Rating sites	+/–
14	Greaves, 2012 [30]	J Med Internet Res	Original	United Kingdom	Rating sites	+/–
15	Greaves, 2013 [19]	BMJ Qual Saf	Opinion paper	United Kingdom	Social media in general	+/–
16	Hammond, 2008 [45]	Guidelines in Practice	Opinion paper	n/a	Rating sites	+
17	Kadry, 2011 [31]	J Med Internet Res	Original	United States	Rating sites	+/–
18	Lagu, 2010 [32]	J Gen Intern Med	Original	United States	Rating sites	+/–
19	Lopez, 2012 [46]	J Gen Intern Med	Original	United States	Rating sites	+/–
20	McCartney, 2009 [47]	BMJ	Opinion paper	United Kingdom	Rating sites	–
21	Reimann, 2010 [33]	BMC Health Serv Res	Original	n/a	Rating sites	+/–
22	Rozenblum, 2013 [48]	BMJ Qual Saf	Editorial	n/a	Social media in general	+
23	Segal, 2012 [34]	J Med Internet Res	Original	United States	Rating sites	+/–
24	Strech, 2011 [35]	J Med Internet Res	Opinion paper	n/a	Rating sites	+/–
25	Tanne, 2013 [36]	BMJ	News item	United States	Rating sites	+/–
26	Tello, 2013 [49]	Am J Med Qual	Correspondence	Peru	Facebook	–
27	Thielst, 2011 [37]	Front Health Serv Manage	Opinion paper	United States	Social media in general	+
28	Timian, 2013 [20]	Am J Med Qual	Original	United States	Facebook	+
29	Trigg, 2011 [3]	J Health Serv Res Policy	Essay	n/a	Rating sites	+/–

^aRating sites: various types of health care rating sites like physician rating sites or hospital rating sites.

^bA subjective assessment of the authors’ attitude towards the relation between social media and quality of health care (+: positive, +/–: positive with reservations, –: negative).

^cWe refer to three different papers by Greaves et al in 2012: see citations [28-30].