Interim clinical outcomes in the collaborative initial glaucoma treatment study comparing initial treatment randomized to medications or surgery☆
Received 26 June 2001; accepted 8 August 2001.
Abstract
Purpose
To report interim outcome data, using all available follow-up through 5 years after treatment initiation, in the Collaborative Initial Glaucoma Treatment Study (CIGTS).
Design
Randomized clinical trial.
Participants
Six hundred seven newly diagnosed glaucoma patients.
Methods
In a randomized clinical trial, 607 patients with newly diagnosed open-angle glaucoma were initially treated with either medication or trabeculectomy (with or without 5-fluorouracil). After treatment onset and early follow-up, patients were evaluated clinically at 6-month intervals. In addition, quality of life telephone interviews were conducted at similar frequency to the clinical visits. Patients in both arms of CIGTS were treated aggressively in an effort to reduce intraocular pressure (IOP) to a level at or below a predetermined target pressure specific for each individual eye. Visual field (VF) scores were analyzed by time-specific comparisons and by repeated measures models.
Main outcome measures
VF loss was the primary outcome variable in CIGTS. Secondary outcomes of visual acuity (VA), IOP, and cataract were also studied.
Results
On the basis of completed follow-up through 4 years and partially completed through 5 years, VF loss did not differ significantly by initial treatment. Over the entire period of follow-up, surgical patients had a greater risk of substantial VA loss compared with medical patients. However, by 4 years after treatment, the average VA in the two groups was about equal. Over the course of follow-up, IOP in the medicine group has averaged 17 to 18 mmHg, whereas that in the surgery group averaged 14 to 15 mmHg. The rate of cataract requiring removal was greater in the surgically treated group.
Conclusions
Both initial medical or initial surgical therapy result in about the same VF outcome after up to 5 years of follow-up. VA loss was greater in the surgery group, but the differences between groups seem to be converging as follow-up continues. When aggressive treatment aimed at substantial reduction in IOP from baseline is used, loss of VF can be seen to be minimal in general. Because 4 to 5 years of follow-up in a chronic disease is not adequate to draw treatment conclusions, these interim CIGTS outcomes do not support altering current treatment approaches to open-angle glaucoma.
Manuscript no. 210440.
aDepartment of Ophthalmology and Visual Sciences, Kellogg Eye Center, The University of Michigan, Ann Arbor, Michigan, USA
bDepartment of Epidemiology, The University of Michigan, Ann Arbor, Michigan, USA
cDepartment of Biostatistics, The University of Michigan, Ann Arbor, Michigan, USA
dDepartment of Health Behavior and Health Education, The University of Michigan, Ann Arbor, Michigan, USA
eDepartment of Ophthalmology, University of Kentucky, Lexington, Kentucky, USA
Reprint requests to Paul R. Lichter, MD, W. K. Kellogg Eye Center, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105 USA
☆ The CIGTS is funded by the National Institutes of Health, National Eye Institute, Bethesda, Maryland, grant numbers EY09100, EY09140, EY09141, EY09142, EY09143, EY09144, EY09145, EY09148, EY09149, EY09150, and EY09639.
ABSTRACT