Purpose: To delineate the immune parameters associated with reactivation of cytomegalovirus (CMV) retinitis in patients for whom highly active antiretroviral therapy (HAART) was not successful.
Methods: Prospective, longitudinal observational study of a cohort of 102 patients with CMV retinitis treated with HAART and being followed up at the AIDS Ocular Research Unit of the University of California, San Diego from November 1995 to November 1998. The study included serial clinical and fundus photographic examinations with CD4 T-lymphocyte counts and HIV viral load measurements.
Results: Forty-seven of the 102 patients with CMV retinitis responded to HAART. Thirty-five of the patients were successfully withdrawn from anti-CMV therapy. During a median follow-up of 74.71 weeks (range, 4.86-144 weeks) after discontinuation of anti-CMV therapy, four patients experienced a reactivation of CMV retinitis. In each case, the CD4 count decreased before reactivation to a median of 31.5 cells/mm3 (mean, 31.25 cells/mm3; range, 23-39 cells/mm3). The association between the CD4 count decreasing to less than 50 cells/mm3 and reactivation of CMV retinitis was statistically significant (P < 0.0003).
Conclusion: Four patients treated with HAART experienced reactivation of CMV retinitis as their CD4 count decreased. The threshold CD4 count below which reactivation of CMV retinitis occurred in patients for whom HAART was not successful appeared to be 50 cells/mm3. Despite an initial response to HAART, patients are still at risk for reactivation of CMV retinitis if their CD4 count decreases to less than 50 cells/mm3. The HIV viral load did not appear to predict CMV reactivation.