Background:
STI clinics are important venues for the identification of HIV-infected persons. Increasing the uptake of HIV testing in these venues may increase the proportion of HIV-infected persons who are aware of their infection and, with appropriate interventions, may decrease HIV transmission.

Objective:
We evaluated the effect of the introduction of rapid HIV testing and opt-out consenting on HIV testing uptake and HIV positivity rate among clients of the Denver Metro Health Clinic (DMHC).

Method:
We evaluated HIV testing trends over 4 periods; p1: the year before introduction of rapid testing in December 2003 (12/2002 – 11/2003; N = 9,340 ); p2: the interval during which rapid testing was offered as alternative to standard EIA testing (12/2003 – 5/2004; N = 4,567); p3: the interval during which rapid testing was offered as the only testing option (6/2004 – 3/2005; N = 8,075); and p4: 6 months following the introduction of opt-out consenting (4–9/2005, N=2,825).

Result:
Over the 4 time periods, HIV testing uptake increased from 80.0% in p1, to 97.3% in p2, 92.8% in p3, and 96.3% in p4. Among MSM (the most important population at risk for HIV in the Denver area), these percentages were 80.1%, 87.0%, 90.4%, and 91.0% respectively. Overall HIV sero-positivity increased from 0.5% to 0.7% between p1 and p4.

Conclusion:
The introduction of the HIV rapid test as the routine mode of HIV testing at DMHC and subsequent opt-out consenting, increased testing uptake by 20% among all patients and 14% among MSM. Overall HIV positivity rate increased by 40%. Opt-out consenting increased testing uptake, but this increase was small compared to the increase that followed the introduction of rapid testing.

Implications:
HIV rapid testing appears to increase testing uptake and may increase the number of newly diagnosed HIV infections in STI settings.