The collaborative initial glaucoma treatment study: Study design, methods, and baseline characteristics of enrolled patients

doi:10.1016/S0161-6420(99)90147-1

Ophthalmology

Volume 106, Issue 4, 1 April 1999, Pages 653-662

Presented in part at the Association for Research in Vision and Ophthalmology annual meeting, Ft. Lauderdale, Florida, May 1998, and the Society for Clinical Trials annual meeting, Atlanta, Georgia, May 1998.

https://doi.org/10.1016/S0161-6420(99)90147-1 Get rights and content

Abstract

Objective

The Collaborative Initial Glaucoma Treatment Study (CIGTS) is a randomized, controlled clinical trial designed to determine whether patients with newly diagnosed open-angle glaucoma (primary, pigmentary, or pseudoexfoliative) are better treated by initial treatment with medications or by immediate filtration surgery.

Design

Randomized, controlled clinical trial.

Participants

A total of 607 patients with open-angle glaucoma were enrolled.

Intervention

Patients randomized to initial medications (n=307) received a stepped regimen of medications to lower intraocular pressure. Those randomized to initial surgery (n=300) underwent trabeculectomy to lower intraocular pressure.

Main outcome measures

Progression in visual field loss constitutes the study’s primary outcome variable. Secondary outcomes include health-related quality of life, visual acuity, and intraocular pressure.

Results

Randomized assignment resulted in a balanced distribution between treatment groups for most demographic and clinical measures assessed at enrollment. More males than females were enrolled (55% were males), and a substantial percentage (38.1%) of enrollees were blacks. Most enrollees (90.6%) were diagnosed with primary open-angle glaucoma; the remainder had either pseudoexfoliative (4.8%) or pigmentary (4.6%) forms of open-angle glaucoma.

Conclusions

Follow-up of this well-characterized group of patients should provide well-rounded guidance, based on both traditional ophthalmic measures and patients’ perspectives on their health-related quality of life, on how best to initially treat open-angle glaucoma.

Section snippets

Rationale

Open-angle glaucoma, one of the major causes of impaired vision worldwide, is a condition characterized by damage to and loss of optic nerve axons, resulting most commonly in loss of peripheral aspects of the visual field, which may progress to loss of central vision. Treatment of open-angle glaucoma has been directed to lowering the IOP based on several clinical observations:

1.
Many patients with open-angle glaucoma have elevated IOP.
2.
Those patients who lack elevated IOP are thought to have a

Organization

Fourteen clinical centers and 1 satellite center participated in the recruitment of patients and are now actively following enrolled patients (refer to Appendix for a list of study centers and personnel). The study’s protocol and informed consent were approved by human studies’ review boards at all participating centers. Three resource centers provide a central structure to the project (refer to Appendix). The Administrative Center provides direction to the study; the Coordinating Center

Treatment sequences

In the surgical arm, the patient’s study eye underwent trabeculectomy within 14 days of randomization. If further treatment was required (refer to description of intervention failure), argon laser trabeculoplasty was the next treatment step, followed by a sequence of medications, repeat trabeculectomy with an antifibrotic agent, and then medication. In the medical arm, patients received a sequence of medications that usually began with a topical beta-blocker, followed by an alternate single

Discussion

Unlike several other clinical trials of glaucoma treatment in which the randomization unit was the eye, such as the Glaucoma Laser Trial31 and the Advanced Glaucoma Intervention Study,23 the CIGTS randomization unit was the patient. Even though patients might have presented with only one eye meeting the criteria for treatment, they had to consent to participate based on the foreknowledge that should their other eye eventually meet the treatment criteria, it would receive the same treatment

Acknowledgements

In developing the protocol for this study, the CIGTS Investigators benefited greatly from access to the AGIS protocol (Advanced Glaucoma Intervention Study Manual of Operations: National Technical Information Service, Accession No. PB93-220192. Springfield, VA) and thank that study’s investigators for the wealth of procedural information that was available from their efforts. In particular, the authors thank Marshall H. Becker, PhD, MPH, who contributed substantially to the development and

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^☆: Supported by the National Institutes of Health, National Eye Institute, grants EY09100, EY09140, EY09141, EY09142, EY09143, EY09144, EY09145, EY09148, EY09149, EY09150, and EY09639.

^∗: The CIGTS Study Group members are listed in the Appendix at the end of this article.

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The collaborative initial glaucoma treatment study: Study design, methods, and baseline characteristics of enrolled patients☆

Abstract

Objective

Design

Participants

Intervention

Main outcome measures

Results

Conclusions

Section snippets

Rationale

Organization

Treatment sequences

Discussion

Acknowledgements

Ophthalmology

Am J Ophthalmol

Ophthalmology

Am J Ophthalmol

J Chronic Dis

Am J Ophthalmol

Ophthalmology

Am J Ophthalmol

Ophthalmology

Control of chronic simple glaucoma with primary medical, surgical and laser treatment

Trans Ophthalmol Soc UK

Early trabeculectomy versus conventional management in primary open angle glaucoma

Br J Ophthalmol

The benefit of early trabeculectomy versus conventional management in primary open angle glaucoma relative to severity of disease

Eye

Immediate surgery for the treatment of open angle glaucoma?

Eye

The influence of prior therapy on the success of trabeculectomy

Arch Ophthalmol

Cost analysis of early trabeculectomy versus conventional management in primary open angle glaucoma

Eye

The role of early surgery for open-angle glaucoma

Ophthalmology Clinics of North America

Primary surgery for primary open angle glaucoma - justified or not?

Br J Ophthalmol

Adverse effects of topical antiglaucoma medication. I. The conjunctival cell profile

Arch Ophthalmol

Adverse effects of topical antiglaucoma medication. II. The outcome of filtration surgery

Arch Ophthalmol