Original article
The Advanced Glaucoma Intervention Study (AGIS): 12. Baseline risk factors for sustained loss of visual field and visual acuity in patients with advanced glaucoma

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Abstract

PURPOSE: To examine the relationships between baseline risk factors and sustained decrease of visual field (SDVF) and sustained decrease of visual acuity (SDVA).

DESIGN: Cohort study of participants in the Advanced Glaucoma Intervention Study (AGIS).

METHODS: This multicenter study enrolled patients between 1988 and 1992 and followed them until 2001; 789 eyes of 591 patients with advanced glaucoma were randomly assigned to one of two surgical sequences, argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) or trabeculectomy-ALT-trabeculectomy (TAT). This report is based on data from 747 eyes. Eyes were offered the next intervention in the sequence upon failure of the previous intervention. Failure was based on recurrent intraocular pressure elevation, visual field defect, and disk rim criteria. Study visits occurred every 6 months; potential follow-up ranged from 8 to 13 years. For each intervention sequence, Cox multiple regression analyses were used to examine the baseline characteristics for association with two vision outcomes: SDVF and SDVA. The magnitude of the association is measured by the hazard ratio (HR), where HR for binary variables is the relative change in the hazard (or risk) of the outcome in eyes with the factor divided by the hazard in eyes without the factor, and HR for continuous variables is the relative change in the hazard (or risk) of the outcome in eyes with a unit increase in the factor.

RESULTS: Characteristics associated with increased SDVF risk in the ATT sequence are: less baseline visual field defect (hazard ratio [HR] = 0.86, P < .001, 95% CI = 0.82–0.90), male gender (HR = 2.23, P < .001, 1.54–3.23), and worse baseline visual acuity (HR = 0.96, P = .001, 0.94–0.98); in the TAT sequence: less baseline visual field defect (HR = 0.93, P = .001, 0.89–0.97) and diabetes (HR = 1.87, P = .007, 1.18–2.97). Characteristics associated with increased SDVA risk in both treatment sequences are better baseline acuity (ATT: HR = 1.05, P < .001, 1.02–1.09; TAT: HR = 1.06, P < .001, 1.03–1.08), older age (ATT: HR = 1.05, P = .001, 1.02–1.08; TAT: HR = 1.04, P = .002, 1.01–1.06), and less formal education (ATT: HR = 1.92, P = .001, 1.29–2.88; TAT: HR = 1.77, P = .002, 1.22–2.54).

CONCLUSIONS: For SDVF, risk factors were better baseline visual field in both treatment sequences, male gender, and worse baseline visual acuity in the ATT sequence, and diabetes in the TAT sequence. For SDVA, risk factors in both treatment sequences were better baseline visual acuity, older age, and less formal education.

Section snippets

Design

The AGIS design and methods have been described in detail elsewhere2, 3, 4 and are summarized here. From April 1988 through November 1992, investigators at eleven AGIS clinical centers enrolled a total of 789 eyes of 591 patients. Eligible eyes were randomized to one of two intervention sequences: argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) or trabeculectomy-ALT-trabeculectomy (TAT). The first intervention was administered soon after enrollment; the second and third

Methods

To be eligible for AGIS, patients had to be 35 to 80 years old and eligible eyes had to be phakic and have either (1) advanced primary open-angle glaucoma without previous glaucoma surgery or (2) residual open-angle glaucoma (without any peripheral anterior synechia) 4 or more weeks after laser iridotomy. We considered glaucoma in an eye to be advanced when, in the presence of at least some glaucomatous visual field loss, the disease could not be adequately controlled by medications alone. Eyes

Results

Table 1 presents either the relative frequencies or means of the baseline characteristics (listed in Table 2) considered in these analyses. The average baseline visual field defect score was 8.4, and the average baseline BCVA score was 79.5 letters (about 20/25). All eyes had at least one AGIS intervention, 28% (208/747) had at least two, and 5% (39/747) had three or more. More details on intervention failure and risk factors for intervention failure are provided in AGIS Report 11.1 Although

Discussion

This study was undertaken to explore baseline risk factors for vision loss in eyes of patients with advanced glaucoma rather than to test specific existing hypotheses. Analyses were conducted within each treatment sequence, because we did not assume that the risk factors would be the same for both sequences. Further, the statistical significance of risk factors may depend on specific duration of follow-up.

In both the ATT sequence and the TAT sequence, an increased risk of SDVF is associated

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    This study was supported by grants from the National Eye Institute and the Office of Research on Minority Health (grant numbers U10 EY06824 through U10 EY06827, U10 EY06830 through U10 EY06835, U10 EY07057, and U10 EY09640). The two agencies are part of the National Institutes of Health, U.S. Department of Health and Human Services.

    The writing team members for this paper are: Beth Blackwell, ScD, Douglas Gaasterland, MD, Fred Ederer, MA, FACE, Leonard G. Dally, MSc, Paul Van Veldhuisen, MS, Bruce E. Prum, MD, Marshall Cyrlin, MD, L. Jay Katz, MD, Howard Weiss, MD, Paul Lichter, MD, and Jacob Wilensky, MD.

    (A complete list of staff in the Advanced Glaucoma Intervention Study appears at the end of AGIS Report 11 [AJO 2002;134:481–498]).

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