This secondary analysis of the Protocol S trial from the DRCR Retina Network assessed the cost-effectiveness of 0.5 mg ranibizumab versus panretinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR).
Study design
This was a preplanned secondary analysis of Protocol S, including 213 adults with PDR, with or without center-involved diabetic macular edema (CI-DME) and vision loss (20/32 or worse) at baseline. The data included more than 5 years of follow-up, with simulation of results through 10 years. The ranibizumab group was treated as often as monthly while the PRP group received treatment at baseline and again during follow-up if neovascularization worsened.
The main outcome measure was the incremental cost-effectiveness ratio (ICER), calculated by dividing the total cost of the intervention by the incremental gain in quality-adjusted life-years (QALYs), with ICER and cost-effectiveness being inversely correlated. The range of $50,000 to $150,000 per QALY is frequently cited as being cost effective in the US.
Outcomes
For patients without CI-DME at baseline, the ICER was $582,268/QALY at 5 years and $742,202/QALY at 10 years. Among patients with CI-DME, the ICER was $65,576/QALY and $63,930/QALY at 5 and 10 years, respectively.
Limitations
A significant proportion of individuals were lost to follow-up during the 5-year study. The study used BCVA of the study eye or better-seeing eye as a surrogate for overall health-related quality of life but that may not reflect other potential therapeutic benefits or the impact on peripheral visual fields. Direct medical costs were measured, but the analysis did not capture indirect costs such as caregiver cost, transportation costs, and time away from work; these factors may disproportionately influence the ranibizumab group which had more injections and office visits.
Clinical significance
This analysis suggests that 0.5 mg ranibizumab, as administered in the Protocol S trial for PDR, is within the reference range frequently considered as cost-effective in the United States for those with vision-impairing CI-DME at baseline, but not for those without CI-DME. This data may be considered in conjunction with other patient-specific factors when selecting treatments for PDR.