Table 3.

Estimated crude incidence rates and HRs for time to HIV by the quintiles of age at first sex

	Crude incidence rate per 100 person-years (95% CI)	Unadjusted HR (95% CI)	p Value	Adjusted HR* (95% CI)	p Value
Age at first sex (years)
<15	12.0 (8.0 to 18.0)	1.97 (1.07 to 3.63)	0.029	1.78 (0.96 to 3.29)	0.066
15–16	7.2 (5.7 to 9.0)	1.11 (0.69 to 1.80)	0.664	0.90 (0.53 to 1.46)	0.633
17–18	6.1 (4.1 to 9.0)	0.95 (0.53 to 1.69)	0.851	0.82 (0.45 to 1.47)	0.496
19–20	5.1 (2.9 to 9.0)	0.78 (0.39 to 1.60)	0.503	0.72 (0.35 to 1.67)	0.365
21+	6.4 (4.2 to 9.8)	1		1

^*Adjusted for age, number of lifetime sex partners, cohabitation status, level of education, ever used condom with vaginal sex.