Table 2.

A list of included studies (n=28) with ethical, legal, and social issue components (with ethical approval of study). All platforms listed by each paper do not satisfy the ethical, legal, and social issue components equally.

Author (year)	Platform(s) concerned	Ethical, legal, and social issue components
		Research ethics committee	Open and non-discriminative participation	Web-based information sheet	Informed e-consent	Opt out from study	Personal data protection measures
Adler et al (2014) [27]	UKa	✓	✓				✓
Bajardi et al (2014) [28]	BEb, FRc, ITd, NLe, PTf, SEg, UK	✓	✓	✓	✓		✓
Bajardi et al (2014) [29]	BE, FR, IT, NL, PT, SE, UK	✓	✓		✓		✓
Brooks-Pollock et al (2011) [19]	UK	✓	✓	✓	✓		✓
Cantarelli et al (2014) [14]	BE, FR, IT, NL, PT, SE, UK	✓	✓	✓	✓		✓
Debin et al (2013) [30]	FR	✓		✓			✓
Debin et al (2014) [10]	FR	✓			✓
Eames et al (2012) [31]	UK		✓				✓
Eames et al (2012) [32]	UK	✓	✓			✓	✓
Friesma et al (2009) [5]	BE, NL		✓	✓
Guerrisi et al (2016) [33]	BE, FR, IT, NL, PT, UK		✓	✓			✓
Kjelso et al (2016) [20]	DKh		✓			✓
Koppeschaar et al (2017) [17]	BE, DK, FR, IEi, IT, NL, PT, SE, ESj, UK	✓	✓	✓	✓		✓
Land-Zandstra et al (2016) [34]	BE, NL		✓	✓
Loubet et al (2016) [35]	FR	✓		✓	✓	✓	✓
Loubet et al (2016) [36]	FR	✓		✓	✓	✓	✓
Marquet et al (2006) [21]	NL		✓	✓			✓
Paolotti et al (2010) [37]	IT		✓	✓
Peppa et al (2017) [38]	UK	✓	✓		✓
Perrotta et al (2017) [39]	IT		✓				✓
Perrotta et al (2017) [40]	IT		✓				✓
Pini et al (2017) [18]	SE					✓	✓
Smolderen et al (2007) [41]	NL		✓				✓
Tilston et al. (2010) [42]	UK	✓	✓	✓
van Noort et al (2007) [11]	BE, NL, PT		✓	✓
van Noort and Stollenwerk (2008) [43]	BE, IT, NL, PT		✓			✓
van Noort et al (2015) [9]	BE, IT, NL, PT	✓		✓
Vandendijck et al (2013) [6]	BE		✓			✓	✓

^aUK: United Kingdom.

^bBE: Belgium.

^cFR: France.

^dIT: Italy.

^eNL: the Netherlands.

^fPT: Portugal.

^gSE: Sweden.

^hDK: Denmark.

ⁱIE: Ireland.

^jES: Spain.