Association between participant characteristics and syphilis status in women in the early cohort (n=3692)
| Variable | Syphilis negative n=3414 (92.5%) | Syphilis positive n=278 (7.5%) | Syphilis seroprevalence crude POR (95% CI) | P value | Syphilis seroprevalence adjusted POR (95% CI) | P value |
| Demographics | ||||||
| Age category (years) | 0.007 | 0.001 | ||||
| 16–29 | 962 (28.2) | 64 (23.0) | 0.90 (0.45 to 1.80) | 0.776 | 1.22 (0.59 to 2.56) | 0.591 |
| 30–39 | 1521 (44.6) | 154 (55.4) | 1.38 (0.71 to 2.67) | 0.344 | 1.31 (0.66 to 2.62) | 0.443 |
| 40–49 | 795 (23.3) | 50 (18.0) | 0.86 (0.42 to 1.73) | 0.663 | 0.64 (0.31 to 1.32) | 0.228 |
| ≥50 | 136 (4.0) | 10 (3.6) | Ref | Ref | Ref | Ref |
| Black race | 1925 (56.4) | 203 (73.0) | 2.09 (1.59 to 2.75) | <0.001 | 1.95 (1.46 to 2.60) | <0.001 |
| Hispanic ethnicity | 914 (26.8) | 61 (21.9) | 0.77 (0.57 to 1.03) | 0.080 | ||
| Single relationship status | 2155 (63.2) | 183 (66.1) | 1.13 (0.87 to 1.47) | 0.347 | ||
| Low Income (<$12 000/year) | 1934 (58.5) | 202 (76.8) | 2.35 (1.75 to 3.15) | <0.001 | 2.01 (1.48 to 2.73) | <0.001 |
| Self-reported history of syphilis | 29 (0.85) | 48 (17.3) | 24.6 (15.2 to 39.7) | <0.001 | ||
| Currently pregnant | 69 (2.0) | 10 (3.6) | 1.82 (0.93 to 3.58) | 0.082 | ||
| Medical comorbidities | ||||||
| HIV infection | 2501 (73.3) | 232 (83.5) | 1.84 (1.33 to 2.55) | <0.001 | 1.84 (1.30 to 2.60) | <0.001 |
| Hepatitis C (antibody positive) | 1072 (31.4) | 131 (47.3) | 1.96 (1.53 to 2.51) | <0.001 | 1.46 (1.08 to 1.96) | 0.013 |
| Drug and alcohol use | ||||||
| Problem alcohol use (>7 drinks/week) | 384 (11.3) | 50 (18.0) | 1.69 (1.22 to 2.34) | 0.001 | ||
| Active or prior drug use | 2548 (74.8) | 259 (93.2) | 4.60 (2.87 to 7.38) | <0.001 | 3.25 (1.94 to 5.44) | <0.001 |
| Active or prior IDU | 1021 (29.9) | 109 (39.2) | 1.51 (1.18 to 1.94) | 0.001 | ||
| Sexual history | ||||||
| Number of lifetime sex partners | <0.001 | <0.001 | ||||
| >100 | 215 (6.3) | 50 (18.0) | 3.71 (2.62 to 5.27) | <0.001 | 2.88 (1.98 to 4.19) | <0.001 |
| 11–100 | 866 (25.4) | 82 (29.5) | 1.51 (1.14 to 2.00) | 0.004 | 1.18 (0.87 to 1.60) | 0.296 |
| 0–10 | 2332 (68.3) | 146 (52.5) | Ref | Ref | Ref | Ref |
| Transactional sex (ever) | 1065 (31.3) | 179 (64.6) | 4.00 (3.10 to 5.18) | <0.001 |
Values expressed as n (% of non-missing results); reference levels for variables: age (≥50 years old), race (white, Asian, Native American, Pacific Islander and other), ethnicity (non-Hispanic), relationship status (married/living with a partner), income (US$≥12 000), self-reported history of syphilis (no self-reported history of syphilis), currently pregnant (not pregnant), HIV status (HIV negative); hepatitis C (negative), problem alcohol use (≤7 drinks a week), active or historical use of cocaine/crack, heroin, methamphetamines or other non-IDU drugs (no active or historical drug use); number of lifetime sex partners (0–10 lifetime partners) and history of transactional sex (reporting never having sex for drugs, money or shelter); missing data: income (n=123, 3.3%), self-reported history of syphilis (n=3, 0.1%), currently pregnant (n=32, 0.9%), marital status (n=7, 0.2%), HCV antibody (n=3, 0.1%), alcohol use (n=83, 2.3%), transactional sex (n=16, 0.4%), active or historical use of cocaine/crack, heroin, methamphetamines or other non-IDU drugs (n=6, 0.2%) and number of lifetime sex partners (n=1, <0.1%). In the multivariable model for women enrolled in the early WIHS cohorts (1994–2002), there were 3692 women of which data for 3562 were used. Backward selection with an alpha level of removal of 0.2 was used, and problem alcohol use was removed from the model.
IDU, injection drug use; POR, prevalence OR; WIHS, Women’s Interagency HIV Study.