BMC Public Health 2008, 8:180 http://www.biomedcentral.com/1471-2458/8/180 Table 1: Self-reported details of responders' characteristics Variable Age Under 21 years 21 – 30 years 31 – 45 years 46 – 60 years Older 61 years Nationality Swiss Other Europe Asia Central/South America Other Sexual orientation Homosexual Heterosexual Bisexual Sexual contacts with ... Men only Women only Both men and women Relationship Living in a monogamous relationship Living in an open relationship with arrangements Living in an open relationship without arrangements Living alone Result of last HIV test Negative serostatus Positive serostatus Never been tested Hepatitis A vaccination status Not vaccinated Vaccinated Vaccination status unknown Hepatitis B vaccination status Not vaccinated Vaccinated Vaccination status unknown Number of past tests for sexually transmitted infections (STI) 0 1–2 3 and more History of sexually transmitted infections (STI) No Yes n (%) responders* 30 (7.5) 144 (35.8) 179 (44.5) 31 (7.8) 11 (2.7) 310 (77.1) 63 (15.7) 7 (1.7) 14 (3.5) 3 (0.7) 241 (60.0) 106 (26.4) 54 (13.4) 131 (32.6) 36 (9.0) 37 (9.2) 124 (30.8) 78 (19.4) 19 (4.7) 150 (37.3) 309 (76.9) 2 (0.5) 78 (19.4) 92 (22.9) 183 (45.5) 112 (27.9) 84 (20.9) 199 (49.5) 102 (25.4) 89 (22.1) 138 (34.3) 141 (35.1) 277 (68.9) 115 (28.6) *n varies per item due to item-non-response. % = relative to the entire sample (n = 402) men or in conjunction with sexual activity (42% infre- quently, 10% frequently and 0.5% used drugs always). The most common substances used in conjunction with sex were alcohol (41%), followed by cannabis (13%), cocaine (5%), methylenedioxymethamphetamine (ecstasy; 5%), sildenafil (viagra; 4%) and other substances (5%), mainly inhalant nitrites (poppers), crystal metham- phetamine (crystal) and Gamma-Hydroxybutyrate (GHB/ GBL). The main reasons for requesting HIV or STI testing were a prior risk situation (46.3%), followed by routine screen- ing without a prior risk situation (24.1%) and clarifica- tion of HIV/STI status due to the beginning of a new relationship (29.6%). 2.5% of clients reported a prior STI as rationale for requesting HIV testing while 2 men (0.5%) were diagnosed with HIV previously and asked for STI testing. Details on the reported previous risk behav- iours are presented in table 3. The most common risk behaviours reported by respondents were oral uptake of Page 4 of 9 (page number not for citation purposes)