Mean age at first anal intercourse according to current sexual behaviour and HIV/STIs
| n | % | Mean AFAI | β* | t | p Value | |
| Behaviour in past 12 months | ||||||
| Number of sexual partners | ||||||
| 0 | 28 | 3 | 17.6 | −0.11 | 3.46 | 0.001 |
| 1–5† | 318 | 39 | 21.3 | – | – | – |
| 6–10 | 166 | 20 | 21.2 | −0.02 | 0.69 | 0.49 |
| 11+ | 306 | 37 | 20.6 | −0.12 | 3.47 | 0.001 |
| Behaviour at most recent sexual encounter | ||||||
| Group sex | ||||||
| No† | 705 | 87 | 21.2 | – | – | – |
| Yes | 109 | 13 | 18.9 | 0.14 | 4.64 | <0.001 |
| Had sex with a casual or occasional partner? | ||||||
| No† | 279 | 34 | 21.5 | – | – | – |
| Yes | 533 | 66 | 20.6 | 0.05 | 1.50 | 0.13 |
| Anal intercourse | ||||||
| Insertive only† | 191 | 24 | 22.2 | – | – | – |
| Receptive only | 229 | 29 | 20.2 | −0.13 | 3.20 | <0.001 |
| Both insertive and receptive | 108 | 13 | 19.8 | −0.10 | 2.56 | 0.01 |
| Did not have anal intercourse | 270 | 34 | 21.2 | −0.08 | 1.87 | 0.06 |
| Were condoms used at all times?‡ | ||||||
| No† | 287 | 53 | 20.4 | – | – | – |
| Yes | 254 | 47 | 21.2 | −0.02 | 0.61 | 0.54 |
| Affected by drugs or alcohol | ||||||
| No† | 632 | 79 | 21.4 | – | – | – |
| Yes | 170 | 21 | 19.4 | −0.06 | 1.89 | 0.06 |
| HIV/STIs | ||||||
| Ever had a test for HIV | ||||||
| Yes† | 694 | 85 | 21.0 | – | – | – |
| No | 123 | 15 | 20.5 | −0.06 | 1.78 | 0.07 |
| HIV status§ | ||||||
| Negative† | 609 | 90 | 21.3 | – | – | – |
| Positive | 67 | 10 | 18.5 | −0.14 | 4.06 | <0.001 |
| Number of infections from STIs in past 12 months¶ | ||||||
| 0 | 612 | 74 | 20.7 | −0.08 | 2.01 | 0.04 |
| 1† | 112 | 14 | 22.4 | – | – | – |
| 2 or more | 98 | 12 | 20.4 | −0.11 | 2.73 | 0.007 |
| Ever diagnosed as having hepatitis A | ||||||
| No† | 746 | 93 | 21.0 | – | – | – |
| Yes | 57 | 7 | 19.8 | −0.14 | 4.37 | <0.001 |
| Ever diagnosed as having hepatitis B | ||||||
| No† | 756 | 94 | 21.0 | – | – | – |
| Yes | 49 | 6 | 19.3 | −0.17 | 5.07 | <0.001 |
| Ever diagnosed as having hepatitis C | ||||||
| No† | 791 | 98 | 21.0 | – | – | – |
| Yes | 14 | 2 | 18.2 | −0.12 | 3.82 | <0.001 |
p Values relate to differences in mean AFAI between each category of a variable and its reference category.
↵* Adjusted for age cohort, education and sexual coercion prior to age 16 years.
↵† Reference category.
↵‡ Of those who had anal intercourse at their most recent sexual encounter (N=543).
↵§ Of men who reported having had an HIV test (N=694).
↵¶ Includes genital herpes, thrush, chlamydia, genital warts, gonorrhoea, pubic lice, syphilis and non-specific urethritis.
AFAI, age at first anal intercourse; β, standardised beta coefficient; STIs, sexually transmissible infections; t, t test.