Table 3.

Application of the full and simple MSM HIV acquisition prediction models to Project Explore control arm participants (1999–2003).

Risk Score Quartile	Men, n (%)	Seroconversions, n (%)	Observed Annual Incidence, % (95% CI)	Hazard Ratio* (95% CI)
Full Score
0–6	631 (30.3)	19 (13.2)	1.11 (0.45, 2.29)	REF
7–11	650 (31.2)	37 (25.7)	1.69 (0.84, 3.02)	1.93 (1.11, 3.36)
12–17	345 (16.6)	29 (20.1)	2.61 (1.19, 4.95)	2.81 (1.58, 5.00)
≥18	455 (21.9)	59 (41.0)	4.62 (2.86, 7.06)	4.52 (2.70, 7.55)
Total	2081 (100)	144 (100)	2.32 (1.96, 2.73)
Simple Score
0	585 (28.1)	19 (13.2)	1.03 (0.38, 2.23)	REF
1–3	493 (23.7)	22 (15.3)	1.42 (0.57, 2.93)	1.37 (0.74, 2.52)
4–11	483 (23.2)	39 (27.1)	2.69 (1.43, 4.60)	2.51 (1.45, 4.33)
≥12	520 (25.0)	64 (44.4)	4.23 (2.65, 6.41)	3.87 (2.32, 6.45)
Total	2081 (100)	144 (100)	2.32 (1.96, 2.73)

CI, confidence interval.

^*Test of trend (continuous and categorical): P<0.0001.