Table 2. Exposures and potential risk factors for acute hepatitis C; bold if included in multivariable analysis.
| Category | Subcategory | Cases (%) | Controls (%) | Univariable | Multivariable | ||
| OR (95%- CI) | p | Adj. OR (95%- CI) | p | ||||
| N | 34 (100.0) | 67 (100.0) | |||||
| Sexual behaviour in the previous 12 months | |||||||
| Number of sex partners | More than 10 | 22 (64.7) | 33 (49.3) | 1.89 (0.81–4.42) | 0.204 | — | 0.939 |
| More than 20 | 17 (50.0) | 27 (40.3) | 1.48 (0.65–3.40) | 0.400 | — | 0.641 | |
| More than 50 | 7 (20.6) | 13 (19.4) | 1.08 (0.39–3.01) | 1.000 | |||
| Anonymous sex partners | More than 50 per cent | 16 (47.1) | 30 (44.8) | 1.10 (0.48–2.51) | 0.836 | ||
| Sex frequency | Twice weekly or more | 9 (26.5) | 17 (25.4) | 1.06 (0.41–2.71) | 1.000 | ||
| Met sex partners through the internet | Often or always | 18 (52.9) | 26 (38.8) | 1.77 (0.77–4.08) | 0.206 | ||
| Met sex partners in saunas | Often or always | 5 (14.7) | 9 (13.4) | 1.11 (0,34–3.62) | 1.000 | ||
| Met sex partners at sex parties | Often or always | 10 (29.4) | 12 (17.9) | 1.91 (0.73–5.02) | 0.209 | ||
| Met sex partners at leather venues | Often or always | 8 (23.5) | 8 (11.9) | 2.27 (0.77–6.70) | 0.155 | ||
| Insertive AI § with non-steady partners | Frequently or always | 21 (61.8) | 24 (35.8) | 2.89 (1.23–6.79) | 0.019 | — | 0.347 |
| Receptive AI § with non-steady partners | Frequently or always | 20 (58.8) | 26 (38.8) | 2.25 (0.97–5.23) | 0.062 | 0.759 | |
| BDSM §§ or fisting with non-steady partners | Frequently or always | 10 (29.4) | 9 (13.4) | 2.69 (0.97–7.44) | 0.063 | — | 0.708 |
| UAI with non-steady partners * | One episode or more | 22 (64.7) | 25 (37.3) | 3.08 (1.30–7.28) | 0.012 | — | 0.288 |
| Five episodes or more | 15 (44.1) | 14 (20.9) | 2.99 (1.22–7.33) | 0.020 | — | 0.653 | |
| STIs and condom attitudes | |||||||
| History of syphilis | In the last 12 months | 10 (29.4) | 9 (13.4) | 2.69 (0.97–7.44) | 0.063 | 0.192 | |
| History of Chlamydia infection | In the last 12 months | 7 (20.6) | 10 (14.9) | 1.48 (0.51–4.30) | 0.575 | ||
| History of gonorrhoea | In the last 12 months | 8 (23.5) | 12 (17.9) | 1.41 (0.51–3.87) | 0.599 | ||
| History of any of the three above | In the last 12 months | 19 (55.9) | 21 (31.3) | 2.78 (1.18–6.50) | 0.020 | — | 0.211 |
| Non-steady partners with syphilis | In the last 12 months | 5 (14.7) | 10 (14.9) | 0.98 (0.31–3.14) | 1.000 | ||
| Non-steady partners with HIV | Presently | 27 (79.4) | 38 (56.7) | 2.94 (1.13–7.70) | 0.029 | — | 0.986 |
| Would engage in UAI if sex partner is seroconcordant for HIV | 22 (64.7) | 39 (58.2) | 1.32 (0.56–3.09) | 0.667 | |||
| Would never engage in any UAI | 4 (11.8) | 22 (32.8) | 0.27 (0.09–0.87) | 0.029 | — | 0.296 | |
| Condoms not considered for prevention of STIs (other than HIV) | 14 (41.2) | 13 (19.4) | 2.91 (1.17–7.24) | 0.031 | — | 0.554 | |
| Sexual exposures since 2000 | |||||||
| UAI* with person known to be HCV positive | 3 (8.8) | 5 (7.5) | 1.20 (0.27–5.35) | 1.000 | |||
| Group sex | Yes | 31 (91.2) | 44 (65.7) | 5.40 (1.49–19.58) | 0.007 | 3,50 (0.84–14.52) | 0.084 |
| Frequently or always † | 15 (44.1) | 14 (20.9) | 3.00 (1.22–7.33) | 0.020 | — | 0.786 | |
| PDE-5 inhibitors ** | Frequently or always † | 15 (44.1) | 12 (17.9) | 3.62 (1.44–9.09) | 0.008 | — | 0.557 |
| Nitrite inhalants or large amounts of alcohol | Frequently or always† | 22 (64.7) | 36 (53.7) | 1.58 (0.67–3.70) | 0.395 | ||
| Dilative sex toys | Usage | 27 (79.4) | 37 (55.2) | 3.13 (1.20–8.17) | 0.028 | — | 0.588 |
| Frequently sharing dilative sex toys | 3 (8.8) | 2 (3.0) | 3.15 (0.50–19.80) | 0.332 | |||
| Anal pain with bloody diarrhoea | Repeatedly | 6 (17.6) | 4 (6.0) | 3.38 (0.88–12.91) | 0.082 | — | 0.384 |
| Rectal trauma with bleeding | Frequently or always † | 7 (20.6) | 3 (4.5) | 5.53 (1.33–23.00) | 0.029 | 6.19 (1.17–32.81) | 0.032 |
| Skin damage (BDSM§§) with bleeding | Yes | 8 (23.5) | 9 (13.4) | 1.98 (0.69–5.72) | 0.261 | ||
| Receptive fisting | Yes | 17 (50.0) | 15 (22.4) | 3.47 (1.43–8.39) | 0.007 | ||
| Frequently or always† | 12 (35.3) | 6 (9.0) | 5.55 (1.86–16.57) | 0.002 | |||
| Frequent receptive fisting without gloves (or gloves shared) | 11 (32.4) | 4 (6.0) | 7.53 (2.18–26.03) | 0.001 | 5.71 (1.50–21.68) | 0.011 | |
| Frequent receptive fisting and sharing of lubricant | 10 (29.4) | 5 (7.5) | 5.17 (1.60–16.69) | 0.006 | — | 0.603 | |
| Nosocomial exposures | |||||||
| Blood or plasma transfusion | Any before 1991 | 2 (5.9) | 5 (7.5) | 0.78 (0.14–4.22) | 1.000 | ||
| Major surgery | Repeatedly | 11 (32.4) | 11 (16.4) | 2.44 (0.93–6.40) | 0.079 | — | 0.507 |
| Major dental treatment | Repeatedly | 2 (5.9) | 10 (14.9) | 0.36 (0.07–1.73) | 0.329 | ||
| Endoscopies (gastro-, colono-, cystoscopies) | Repeatedly | 13 (38.2) | 23 (34.3) | 1.18 (0.50–2.79) | 0.826 | ||
| Acupuncture | Repeatedly | 2 (5.9) | 5 (7.5) | 0.78 (0.14–4.22) | 1.000 | ||
| Other exposures since 2000 | |||||||
| Tattooing | Repeatedly | 4 (11.8) | 9 (13.4) | 0.86 (0.24–3.02) | 0.812 | ||
| Body-piercing | Repeatedly | 7 (20.6) | 5 (7.5) | 3.22 (0.94–11.04) | 0.099 | — | 0.529 |
| Imprisonment | More than 72 h | 0 (0.0) | 2 (3.0) | — | 0.549 | ||
| Shared household with HCV positive person | 4 (11.8) | 5 (7.5) | 1.60 (0.40–6.40) | 0.489 | |||
| Consumption of NADs *** | Yes | 28 (82.4) | 35 (52.2) | 4.27 (1.56–11.64) | 0.004 | 3,25 (1.06–9.96) | 0.040 |
| Monthly or weekly | 7 (20.6) | 3 (4.5) | 5.53 (1.33–23.00) | 0.029 | — | 0.135 | |
| Consumption of NADs and sharing of equipment | 22 (64.7) | 25 (37.3) | 3.08 (1.30–7.28) | 0.012 | — | 0.804 | |
| Multivariable model summary | |||||||
| Hosmer-Lemeshow-Test (χ-square; p) | 6.925 | 0.226 | |||||
| Nagelkerke's pseudo-R-square | 0.327 | ||||||
§
AI = anal intercourse;
§§
BDSM = bondage, dominance/submission, sadism/masochism;
*
UAI = unprotected AI with non-steady partners of unknown HIV serostatus;
**
PDE-5 = phosphodiesterase-5: The risk of penile (rectal) trauma is higher if intercourse is temporally extended by (the partner's) use of PDE-5 inhibitors;
***
NADs = nasally-administered drugs (cocaine, amphetamines, ketamine, etc.);
†
frequently or always when having sex.