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Disclaimer: About 80% to 90% of this piece was written by Laurel A. Rockefeller. The other 10% to 20% was written by Arpi Haroutunian.

Laurel A. Rockefeller

Issue 2, September 17, 2004: Risk Supplement Program

Publication:
Risk Assessment in the management of patients with ocular hypertension. Robert N. Weinreb, MD; David S. Friedman, MD, MPH; Robert D Fechtner, MD; George A Cioffi, MD. Am J Ophthalmol. 2004;138.

Discussion synopsis

• Building upon the parallels made by Girkin et al between coronary heart disease and glaucoma, and relying primarily on data from the OHTS, Olmstead County Study, and 10-year St. Lucia Study, Dr. Weinreb begins the process of creating a risk assessment model for glaucoma that will allow medical practitioners to determine which patients are most likely to experience quality of life affecting vision loss from glaucoma.

• Includes analysis by the panel of experts featured in the supplement of population based studies of patients with OH and glaucoma.

• Measures of risk of disease progression derived from three long-term studies and assumptions based on available data were used to estimate risk of progression from OH to glaucoma and from glaucoma to unilateral blindness for treated and untreated patients over a 15-year period from the OHTS, Olmstead County Study, and 10-year St. Lucia Study.

• Although most glaucoma patients rarely progress to unilateral blindness and most patients experience negative quality of life impacts long before this end point, risk assessment and clinical definitions consider "functional impairment" to be unilateral blindness, not significant quality of life or visual field losses where some vision remains.

  • It is estimated that from 12 to 83 patients would need to be treated to prevent one patient from progressing to unilateral blindness.

  • Patients treated for OH cut the risk for unilateral blindness from 1.5% - 10.5% in untreated to 0.3%.- 2.4% of treated OH patients.

• Global risk assessment of glaucoma should balance age, IOP level, cup-to-disk ratio, and central corneal thickness. Assessments are best grouped into low, moderate, and high risk categories based on these factors. Low risk patients should be monitored but not treated, moderate risk patients given the choice of to treat or not treat, and all high risk patients given treatment. This assessment plays an important role in the management of patients with OH.

• A more precise understanding of long-term vision loss should inform decisions the initiation of therapy

• These estimates will continue to evolve with the availability of new population-based epidemiologic data and improvements in multivariate model testing.

Strengths

• This study does an excellent job reviewing the data from OHTS and the 10-year St. Lucia Study and extrapolating the statistics determining risk.

• While it does not provide clearly proven methodologies, the paper does provide some preliminary guidance to those seeking to determine if a particular patient might be at risk for unilateral blindness, by estimating low, moderate, and high-risk groups and suggesting thresholds for treatment.
  

Weakness

• Unilateral blindness is the end point and definition of "functional impairment" for the purposes of this analysis. Such an absolute endpoint is problematic because the risk of unilateral blindness is so small (1.5% of ocular hypertensive patients in 15 years). Most patients never progress to unilateral blindness, but many do experience quality of life affects that could be prevented by lowering IOP. In defining impairment too strictly, these patients might not receive treatment.
  

Conclusion:

This is a great beginning to developing a risk assessment tool for glaucoma. To determine if a particular patient is at risk and how aggressively to treat that patient, the physician should attempt to estimate that patient's global risk based on currently available evidence, including suspected risk factors, disease progression risks, and life expectancy. As the science and methodology evolves in the coming years, physicians will be able to estimate risk more efficiently.

BACK TO HOMEPAGE

Disclaimer: About 80% to 90% of this piece was written by Laurel A. Rockefeller. The other 10% to 20% was written by Arpi Haroutunian.