Risk Factors for Geographic Atrophy in the CATT Trial

Kanish Mirchia, MBBS; Sophie J. Bakri, MD


September 19, 2014

In This Article

Risk of Geographic Atrophy in the Comparison of Age-Related Macular Degeneration Treatments Trials

Grunwald JE, Daniel E, Huang J, et al; CATT Research Group
Ophthalmology. 2014;121:150-161

Study Summary

CATT has been monumental in comparing the relative safety and efficacy of bevacizumab and ranibizumab as treatments for neovascular age-related macular degeneration (AMD). CATT primarily focused on final visual acuity (VA) between patient groups, while secondarily examining effective dosing schedules, adverse events, and anatomical changes in the retina and comparing the costs of the drugs.

As part of these secondary outcome measures, the two-year results from CATT examined the risk factors for geographic atrophy (GA) in a cohort of the CATT population. When treated for choroidal neovascularization, some patients develop atrophy of the retinal pigment epithelium (RPE) and a choriocapillaris layer. These lesions have not been studied histologically, and their long-term effects are unknown. However, they clinically resemble de novo GA lesions, and the two-year data on incidence of and risk factors for their development have been evaluated here.

The cohort in which the risk factors for GA were studied included 1024 patients out of the original 1185 CATT patients. These patients had no baseline GA as tested by color fundus photography and fluorescein angiography. All patients were aged ≥ 50 years, with untreated, active choroidal neovascularization caused by AMD, as well as baseline VA between 20/25 and 20/320.

Patients were randomly assigned to the following groups:

Bevacizumab injections

   - Monthly/as-needed for two years

   - Monthly for one year and re-randomization to as-needed for one year

Ranibizumab injections

   - Monthly/as-needed for two years

   - Monthly for one year and re-randomization to as-needed for one year

Drug regimen and dosing schedule; demographic data; ocular characteristics; genetic factors; and lesion features on optical coherence tomography, color fundus photography, and fluorescein angiography were studied for association with GA.

Each of the individual risk factors first underwent a univariate analysis. Factors with a P value < .20 were included in a multivariate analysis. Factors with a P value < .05 were further shortlisted into the final multivariate model; the exceptions were drug arm and dosing regimen, which were part of all multivariate models.


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