Improvement in quality of life from photodynamic therapy: a Canadian perspective

Background: The Treatment of Age-Related Macular Degeneration with Photodyn amic Therapy (TAP) Study showed that at I year, photodynamic therapy signif icantly reduced the chances of severe visual loss (15 letters or greater) c ompared with placebo treatment in patients with "predominantly classic" sub foveal choroidal neovascularization (CNV). We performed a study to determin e the expected gain in quality of life associated with photodynamic therapy for the treatment of subfoveal CNV in a Canadian cohort of patients with a ge-related macular degeneration. Methods: We created a decision analysis model to determine the incremental gain in quality-adjusted life years (QALYs) associated with photodynamic th erapy over placebo over a 2-year period. The analysis was conducted using e fficacy data derived from the TAP Study and patient-based utilities collect ed by means of the time tradeoff technique. We conducted one-way and two-wa y sensitivity analyses to determine the robustness of our model. A Monte Ca rlo simulation was used to determine whether the observed gain in QALYs wit h photodynamic therapy was significant. Results: Photodynamic therapy was associated with a relative increase in QA LYs of 11.3% compared with placebo. In one-way and two-way sensitivity anal yses, the relative increase in quality of life associated with photodynamic therapy ranged from 4.2% to 25.7%. The Monte Carlo simulation showed that the gain in QALYs conferred from photodynamic therapy was statistically sig nificant (p < 0.001). Interpretation: Photodynamic therapy improves the quality of life of Canadi ans with predominantly classic subfoveal CNV secondary to age-related macul ar degeneration.