Objectives: Despite life-long maintenance therapy, cytomegalovirus (CMV) retinitis frequently progresses in patients with AIDS. Virological markers that could clarify pathogenesis and identify risk factors for progression are required.
Design and methods: We prospectively recruited 45 patients with CMV retinitis. Blood and urine samples were collected before and after induction therapy, and on a monthly basis thereafter during routine medical and ophthalmological assessment, and at any time retinitis progressed. CMV load was measured by quantitative-competitive polymerase chain reaction (PCR).
Results: The median time to first progression of retinitis was 78 days and to death was 8.7 months. Eighty-five per cent of patients who were PCR-positive at diagnosis of retinitis became PCR-negative after 21 days of ganciclovir induction therapy. Six patients who remained PCR-positive after 21 days of treatment had a significantly higher CMV load at presentation (P = 0.005), and a shorter time to first progression of retinitis of 40 days. High CMV loads in blood at presentation were associated with a shorter time to progression (P = 0.16; relative hazard, 1.57) and a significantly shorter time to death (P = 0.004; relative hazard, 1.76). This significant relationship with survival remained after adjustment for potential confounding variables (CD4 count, age, method of drug administration).
Conclusions: We conclude that CMV load in the blood of AIDS patients is an important factor in the pathogenesis of retinitis, and quantification of CMV could be used to both select patients for controlled clinical trials and to optimize individual anti-CMV induction therapy.