Table 2.
Analysis of Predictors and Calculation of Risk Score in the Derivation Cohort
| Univariate | Multivariatea | Stepwiseb | Risk Scorec | |||||
|---|---|---|---|---|---|---|---|---|
| Enrollment Characteristic | Crude HR (95% CI) | P Value | Adjusted HRb (95% CI) | P Value | Adjusted HRb (95% CI) | P Value | Regression Coefficient | |
| Demographic characteristics | ||||||||
| Age <21 yd | 1.22 (.42–3.52) | .710 | ||||||
| Education <8 yd | 0.83 (.23–2.98) | .778 | ||||||
| Married | 0.74 (.23–2.36) | .610 | ||||||
| Polygamous relationship | 2.42 (.67–8.67) | .176 | ||||||
| Marriage duration <1 yd | 3.00 (.94–9.59) | .063 | 2.60 (.74–9.17) | .136 | ||||
| Partner characteristics | ||||||||
| Partner age difference (years older)d | 1.06 (.98–1.16) | .158 | ||||||
| Partner uncircumcisede | 1.31 (.35–4.84) | .686 | ||||||
| Partner HIV status unknown | 5.84 (2.05–16.65) | .001 | 10.75 (3.13–36.94) | <.001 | 11.53 (3.39–39.26) | <.001 | 2.45 | 6 |
| Sexual behavior and practices | ||||||||
| Age at sexual debut <17 yd | 2.06 (.69–6.14) | .196 | ||||||
| Lifetime No. of sexual partnersd | 1.40 (1.18–1.67) | <.001 | 1.44 (1.20–1.75) | <.001 | 1.50 (1.23–1.82) | <.001 | 0.41 | 1 |
| History of trading sex | 1.57 (.35–7.02) | .554 | ||||||
| Any condomless sex in the past month | 0.82 (.29–2.34) | .714 | ||||||
| Any vaginal washing in the past week | 1.22 (.41–3.64) | .722 | ||||||
| Any vaginal drying in the past week | 1.64 (.52–5.24) | .401 | ||||||
| STIs and genital tract infections | ||||||||
| History of STIse | 2.38 (.53–10.65) | .255 | ||||||
| Chlamydia trachomatis | 1.15 (.15–8.83) | .895 | ||||||
| Syphilis | 6.72 (.87–51.78) | .067 | 10.80 (1.29–90.50) | .028 | 9.05 (1.11–73.95) | .040 | 2.20 | 5 |
| Bacterial vaginosis | 4.29 (1.49–12.36) | .007 | 2.59 (.82–8.21) | .104 | 2.61 (.83–8.17) | .099 | 0.96 | 2 |
| Candidiasis | 3.11 (1.09–8.87) | .034 | 3.54 (1.09–11.51) | .036 | 3.51 (1.08–11.37) | .037 | 1.25 | 3 |
Abbreviations: CI, confidence interval; HIV, human immunodeficiency virus; HR, hazard ratio; STI, sexually transmitted infection; y, years.
aCovariates selected for multivariate analysis were based on factors associated with HIV infection (P < .10) in univariate analysis.
bCovariates selected for the stepwise multivariate model based on lowest Akaike information criterion score from stepwise procedure.
cPoints were assigned to each risk factor by dividing each coefficient from the stepwise proportional hazard model by 0.41 (the lowest coefficient value, corresponding to lifetime number of sexual partners) and rounding to the nearest integer.
dContinuous variables were dichotomized using optimal cut-points identified through signal detection receiver operating characteristic analyses. Dichotomized variables were evaluated as predictors if measure predictability was higher using this parameterization instead of the continuous parameterization.
eSelf-reported by women.