Clinical utility of monitoring serum cryptococcal antigen (sCRAG) titers in patients with AIDS

Purpose: The purpose of our study was to define the time course and clinical role of monitoring serum cryptococcal antigen titers (sCRAG) in patients with AIDS-related cryptococcal disease. Method: A retrospective chart review was conducted. The medical records for all HIV-infected patients with positive cryptococcal antigen (CRAG) tests from January 1993 to May 1998 at San Francisco General Hospital (SFGH) were reviewed for sCRAG titer levels and clinical outcomes. Results: Out of the 314 patients found to have positive antigen tests, 136 met the inclusion criteria. Twelve (8.8%) had no change in titer from baseline, 6 (4.4%) had an increase, and 118 (86.8%) had a decrease. Examining the association of sCRAG with time to relapse using a variety of Cox models produced largely null results. Rate of change in sCRAG over time (slope) was not significantly predictive of time to relapse nor of time to definite relapse/probable relapse/persistent disease. Conclusion: Although in the majority of patients, the sCRAG titers appeared to decrease over time, we could not detect a significant correlation between sCRAG titer results of patients who had a clinical response to treatment and sCRAG titers in patients who experienced persistent disease, probable relapse, or definitive relapse of cryptococcal disease. We conclude that follow-up monitoring of the sCRAG titer is not useful in the management of patients with AIDS-related cryptococcal disease on treatment.