Background:
More frequent HIV testing among high-risk persons could decrease HIV transmission.

Objective:
To determine the proportion of MSM previously tested for HIV, estimate the time between HIV tests (i.e. inter-test interval) among MSM, and identify predictors of longer inter-test intervals.

Method:
We collected data as part of routine clinical encounters during 49,662 visits by MSM to STD clinics in 4 cities (Seattle, San Francisco, Denver, and the District of Columbia (DC)), 2002-2006.

Result:
From 2002-2006, a city-specific median of 69.1% (range: 42.5-76.4%) of MSM without prior HIV diagnoses were tested for HIV, a median of 86.7% (range: 79.5-90.0%) of tested men had previous HIV testing (4.5% unknown prior testing status), and a median of 3.9% of tested MSM were newly diagnosed with HIV (range: 2.7-4.6%). Between 2002 and 2006, the median percentage of tested MSM who reported no previous HIV testing decreased from 9.4% to 5.4% (p=0.0119), and the city-specific median inter-test interval decreased from 302 to 243 days (p=0.03). Among MSM with newly diagnosed HIV, the median inter-test interval decreased from 531 days in 2002 to 287 days in 2006 (p=0.001). Predictors of longer inter-test interval included: older age, earlier calendar year, black race (vs. white), and testing in DC or San Francisco (vs. Seattle). Significant predictors of newly diagnosed HIV infection included: younger age; longer inter-test interval; black or Hispanic race/ethnicity (vs. white); clinic in San Francisco (vs. Seattle) and concurrent diagnosis with a bacterial STD.

Conclusion:
In MSM seen at four STD clinics, the percentage of MSM never previously tested is decreasing and MSM are HIV testing more frequently.

Implications:
Public Health authorities should attempt to further decrease the inter-test interval, and should monitor the proportion of MSM previously tested and the inter-test interval as indices of prevention program effectiveness.