“…The included studies were published between 2002 4 and 2019 17 and were carried out mostly in the United States 4,5,8,11,[15][16][17]20,21,[23][24][25][26][27][28][29] with three exceptions, which were conducted in Spain, 18 Germany, 22 and Israel. 19 The most common designs were cross-sectional (n = 13), 11,[16][17][18][19][20][22][23][24][25][26]28,29 followed by retrospective cohort (n = 4), 4,5,8,15 one prospective cohort (n = 1), 21 and one clinical trial (n = 1). 27 The method used to identify POU was mostly questionnaires: two used telephone questionnaires, 15,16 six used a face-to-face interview, 11,17,18,20,21,23 and seven used a self-completed questionnaire with help available from an interviewer (if required).…”