“…The characteristics of these studies show that only 8 out of 38 had national coverage [17-18, 32, 76-81]. As with PWID, these samples were mostly recruited via sexually transmitted infection (STI) clinics, such as studies (7) 15 (12) 19 (16) 13 (7) 16 (12) Central Europe (n = 15) 15 (14) 11 (4) 13 (7) 13 (9) 9 (2) 13 (5) 15 (14) 11 (4) 13 (7) East (n = 15) 14 (13) 14 (13) 12 (10) 14 (14) 13 (11) 14 (11) 14 (14) 14 (14) 14 (12) Total 48 (42) 38 (18) 33 (19) 37 (35) 30 (20) 42 (28) 48 (44) 38 (25) in Austria (1,184), Germany (3,880), Kazakhstan (1,960), Russia (4209), and Spain (4,485), and a large community-recruited sample in Ukraine (2,278) [3,32,77,78,82,83]. Studies in the former Yugoslav Republic of Macedonia and Armenia, described as national samples, were limited by small sample sizes [3,18].…”