Table 2.

Association between serosorting and testing newly positive for HIV and bacterial STIs among MSM attending the Public Health – Seattle & King County STD clinic and Gay City Health Project 2002–2013

	NCCAI n/N (%)*	Serosorting n/N (%)*	No CAI n/N (%)*	aPR (95% CI)** Serosorting vs NCCAI	aPR (95% CI)** Serosorting vs no CAI
HIV-Negative MSM
HIV	421/10,035 (4.2)	255/13,768 (1.9)	147/15,042 (1.0)	0.53 (0.45–0.62)	1.98 (1.61–2.44)
Urethral CT/GC	745/6,078 (12.3)	822/8,386 (9.8)	665/9,436 (7.1)	0.89 (0.80–0.99)	1.48 (1.33–1.65)
Rectal CT/GC	832/5,618 (14.8)	1142/7,661 (14.9)	504/5,895 (8.6)	1.02 (0.93–1.11)	1.72 (1.54–1.91)
Early syphilis	262/10,767 (2.4)	202/14,525 (1.4)	129/16,286 (0.8)	0.76 (0.62–0.92)	1.98 (1.56–2.52)
HIV-Positive MSM
Urethral CT/GC	236/1,277 (18.5)	268/1,390 (19.3)	102/689 (14.8)	1.22 (1.02–1.45)	1.36 (1.11–1.73)
Rectal CT/GC	357/1,390 (25.7)	292/1,220 (23.9)	87/480 (18.1)	0.91 (0.80–1.05)	1.27 (1.00–1.62)
Early syphilis	148/1,717 (8.6)	143/1,642 (9.0)	53/923 (5.7)	1.02 (0.81–1.30)	1.40 (1.02–1.92)

aPR, adjusted prevalence ratio; CI, confidence interval; NCCAI, Non-concordant condomless anal intercourse; CAI, condomless anal intercourse; CT, chlamydia; GC, gonorrhea

^*n/N = number who tested positive out of the total number tested for each behavior

^**HIV models adjusted for age, race, time since last HIV test, number of male sex partners in the past 12 months, methamphetamine use, clinic location, and year of visit. STI models adjusted for age, race, number of male sex partners in the past 12 months, methamphetamine use, clinic location, and year of visit