“…In 19 out 66 studies (28.8%) [14,16,18,23,24,28,34,40,42,44,46,47,53,57,60,66,68,71,72], there was no mention of the study methodological limitations. Self-selection into voluntary insurance and the subsequent sample bias were discussed in 20 studies [13, 15, 17, 19, 22, 25, 26, 41, 50-52, 58, 62, 63, 67, 69, 70, 73, 75, 77], openly acknowledging the related identification problems.…”