Background:  Diagnosing persons with HIV soon after infection could decrease HIV transmission and HIV-associated morbidity.

Methods:  We analyzed data collected as part of a public health HIV testing program and a related effort that provides CD4 testing to newly diagnosed persons in Seattle, Washington. We assessed trends in HIV testing history and CD4 count at time of HIV diagnosis using c² tests and robust linear regression. 

Results:  From January 1995 to July 2008, 696 (0.8%) persons were newly diagnosed with HIV during 85,762 testing encounters. Records included self-reported HIV testing history for 591 (85%) persons, 488 (83%) of whom were men who have sex with men (MSM). The proportion of newly diagnosed MSM who reported never previously HIV testing decreased from 25% in 1995 to 1996 to 5% in 2007 to 2008 (p <0.0001), but remained stable in non-MSM (mean for 2-year periods 40%, range 24 to 60%) (p = 0.8). The median time between last HIV^– test and first HIV⁺ test (inter-test interval) among MSM decreased from 692 to 248 days (p <0.0001). Among non-MSM the median inter-test interval was 805 days (range for 2-year periods 533 to 1702 days), with no temporal trend (p = 0.5). During this same period, 619 persons had CD4 counts measured near the time of HIV diagnosis, 495 (80%) of whom were MSM. The median CD4 count among MSM increased from 390 in 1995 to 1996 to 487 in 2007 to 2008 (p = 0.002). Among non-MSM, the median CD4 count increased from 337 in 1995 to 2000 to 407 in 2001 to 2008 (p = 0.04). Patient reported data on HIV testing history were available for 406 (66%) persons, of whom 347 reported a prior negative test. Shorter inter-test interval was associated with a higher CD4 count, but explained little of the observed CD4 count variance (p = 0.03, R² = 0.014). Among 145 persons HIV tested in the preceding year, 6 (5%) had CD4 counts <200, and 27 (19%) had CD4 counts <350; 36 (45%) of the 75 persons with CD4 counts <200 reported that they had HIV tested in the preceding 2 years. Overall, 66% of all persons diagnosed with HIV had CD4 counts >350.

Conclusions:  These data suggest that persons with HIV, particularly MSM, are being diagnosed earlier in their infection. Many persons with low CD4 counts have HIV tested fairly recently, and may be misclassified as late diagnoses. A growing proportion of persons with newly diagnosed HIV are not candidates for immediate antiretroviral therapy using current guidelines. The generlizability of these findings is uncertain.