Table 4.

Estimated PAR (95% CI) for risk factors for the prevalence and incidence of HIV infection in the MIRA trial

Modifiable risk factors	PAR (95% CI)* (prevalence of HIV infection)	PAR (95% CI)* (incidence of HIV infection)
Combined effect†	0.85 (0.84 to 0.87)	0.77 (0.72 to 0.82)
Age at first sex (<15)	0.26 (0.21 to 0.31)	0.17 (0.10 to 0.21)
Less than high school‡	0.13 (0.10 to 0.17)	NA§
Age at first sex
+ Less than high school	0.32 (0.27 to 0.38)	–
Not cohabiting	0.39 (0.35 to 0.43)	0.54 (0.46 to 0.62)
Number of lifetime male sex partners
Two	0.12 (0.11 to 0.13)	0.11 (0.09 to 0.15)
Three	0.20 (0.18 to 0.21)	0.13 (0.11 to 0.17)
Four or more	0.41 (0.39 to 0.43)	0.16 (0.13 to 0.20)
Biological risk factors
Tested positive for STI¶	0.05 (0.04 to 0.06)	0.03 (0.02 to 0.05)
HSV2	0.82 (0.80 to 0.83)	0.21 (0.14 to 0.31)

^*Age adjusted.

^†Assumes all the risk factors removed from the target population.

^‡Less than 12 years of education.

^§Level of education was not determined to be significant predictor of HIV seroconversion.

^¶Chlamydia, gonorrhoea, syphilis or Trichomonas vaginalis at screening.

HSV2, herpes simplex virus 2; MIRA, Methods for Improving Reproductive Health in Africa; PAR, Population Attributable Risk; STI, sexually transmitted infection.