Fig. 2

Number of apps offering each feature. Feature item No. 1 was present in the following apps: 1, 3, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 19, 20, 21, 22. Feature item No. 2 was present in the following apps: 1, 2, 17, 18, 19, 20. Feature item No. 3 was present in the following apps: 2, 4, 19, 20 (While not having a laboratory field by default, there were apps which automatically displayed supplementary fields and questions in response to an answer to certain conditions such as pregnancy). Feature item No. 4 was present in the following apps: 2, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 21, 22. Feature item No. 5 was present in the following apps: 1, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 21, 22. Feature item No. 6 was present in the following apps: 17. Feature item No. 7 was present in the following apps: 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 21, 22. Feature item No. 8 was present in the following apps: 1, 3, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22 (Apps were also counted if contact was included in an acknowledgment message or in an introduced website)