Repeat Western blot testing after receiving an HIV diagnosis and its association with engagement in care.

Objectives: To examine the prevalence of and factors associated with potentially unnecessary repeat confirmatory testing after initial HIV diagnosis and the relationship of repeat testing to medical care engagement.

Design: South Carolina HIV/AIDS surveillance data for 12,504 individuals who were newly diagnosed with HIV infection between January 1997 and December 2008 were used for this analysis. State law requires that all positive Western blot [WB] results be reported regardless of frequency.

Methods: HIV-infected persons, diagnosed from 1997-2008 and followed through 2009, with repeat positive WB results were compared to those who did not have repeat positive WB results. We defined repeat positive testing as documentation of one or more positive WB obtained ≥90 days following initial WB confirmatory result. HIV care engagement for the period from 2007-2009 was assessed by documentation of CD4+ T-cell/viral load reports to the South Carolina HIV/AIDS surveillance system during each six-month period of a calendar year for those individuals diagnosed prior to the assessment period and still alive at the end. Relative risk [RR] with 95% confidence intervals [CI] and multivariable general linear models were used to assess if any covariates of interest were independently associated with repeat positive confirmatory testing.

Results: A total of 4,237 [34%] of 12,504 HIV-infected individuals had results of repeat positive WB testing reported to the surveillance system during 1997-2008. Persons who had repeat positive WB testing were more likely than persons who did not have repeat WB testing to have progressed to AIDS >1 year following diagnosis [RR: 1.70; 95% CI: 1.61, 1.80] and to be consistently in care [RR: 1.35; 95% CI: 1.24, 1.47] or have sporadic care [RR: 1.80; 95% CI: 1.68, 1.94].

Discussion: Having repeat positive WB tests may be a marker of engaging HIV care. However, given the limited resources available for care, it is important that healthcare reform policy and clinical recommendations promote improvements in communications about previous test results.