BACKGROUND: In the District of Columbia, the first CD4 or viral load laboratory result for an individual is used as a proxy for linkage to care. The extent to which such a proxy is meaningful is in part dependent on the underlying assumption it indicates an HIV positive individual has established a connection with a clinical provider and will subsequently engage in treatment. In order to assess the validity of early laboratory results as a proxy for linkage to care, this analysis compares the impact of differing linkage to care windows on retention in care and time to viral suppression.
METHODS: Adults diagnosed with HIV and reported to the DC surveillance system from 2010-2014 with a CD4 or viral load result within 30 days of diagnosis were considered eligible. The current definition for linkage to care (length of time from diagnosis to first CD4 or viral load) was compared to an adjusted definition (length of time from diagnosis to first CD4 or viral load test at least seven days after diagnosis). Those with a change in their linkage date based on the change in the definition were considered to have shifted. Demographic factors, retention in care, and time to first viral suppression were included as outcomes. Statistical differences were assessed using chi-squared, non-parametric, and logistic regression analyses.
RESULTS: Of 1771 eligible cases, 546 (30.83%) shifted dates within one month of diagnosis, 354 (19.99%) shifted from linkage within one month of diagnosis to 1-3 months; 413 (23.32%) shifted from linkage within one month of diagnosis to greater than three months, and 458 (25.25%) did not change linkage classification. This analysis found that the odds of shifting is 1.62 times greater for those diagnosed from 2010-2013 compared with those diagnosed in 2014. (95% CI: 1.19-2.21) It was also found that those diagnosed at a hospital experienced a 1.51 times greater odds of shifting than those diagnosed by a private physician. (95% CI: 1.02-2.21) No statistical difference was found between those who shifted and those who did not with respect to either retention in care or time to viral suppression. The median time to viral suppression was 141 days among those who shifted compared with 159 days for those who did not.
CONCLUSIONS: This analysis found no differences based on the shifted definition supporting the notion that early laboratory results can be used as an effective proxy for linkage to HIV care.