Incidence and risk factors for developing cytomegalovirus retinitis in HIV-infected patients receiving protease inhibitor therapy

Objective: To assess the incidence and risk factors for cytomegalovirus (CMV) retinitis in HIV-infected patients who initiated protease inhibitor-containing antiretroviral therapy. Design and setting: Prospective, multicentre study. Patients: A cohort of 172 HIV-infected patients with a CD4 cell count below 100 × 106 cells/l at the time of protease inhibitor introduction. Main outcome measures: Confirmed CMV retinitis and mortality, according to CD4 cell count, HIV load, and CMV viraemia. Results: The cumulative incidence of CMV retinitis was 5% at 1 year and 6% at 2 years. Only a positive CMV polymerase chain reaction (PCR) test at therapy initiation was significantly associated with the development of disease (relative hazard, 4.41; 95% confidence interval, 2.12-8.93; P < 0.00001). The 12-month Kaplan-Meier CMV retinitis event rate was 38% in patients who were CMV PCR-positive compared with 2% in those who were CMV PCR-negative (P < 0.001). Mean CMV load was significantly higher in those individuals who went on to develop CMV retinitis (3700 versus 384 copies/ml, P = 0.002). Only 2% of patients remained CMV PCR-positive after 3 months of protease inhibitor therapy, and CMV viraemia was not associated with a worse therapy response or shorter survival. Transient CMV positivity without a higher risk of disease was observed in 7% of patients at the first month on therapy. Conclusions: Protease inhibitor-containing antiretroviral therapy significantly reduces the incidence of CMV viraemia and disease. Although a positive CMV PCR test identifies those patients on therapy at highest risk of CMV retinitis, it is not associated with an increased risk of death or a worse response to protease inhibitor therapy.