Is It Possible to Predict Risk for Developing Macular Degeneration? A New Study Says Yes
by Maureen Duffy
When a close relative is diagnosed with age-related macular degeneration (AMD), family members will often ask, "Will I get macular degeneration, too? What is the likelihood that this will happen to me? Is there any way to predict it?"
A research group, composed of members from the United States and Australia, has attempted to answer those questions, via the development of a clinical eye-specific prediction model for advanced AMD. The researchers used eight predictors—age, sex, education level, race, smoking status, and the presence of pigment abnormality, soft drusen, and maximum drusen size—to create and validate a macular risk scoring system (MRSS).
The Macular Risk Scoring System
The research, entitled A Risk Score for the Prediction of Advanced Age-Related Macular Degeneration: Development and Validation in 2 Prospective Cohorts, was published online ahead of print in the March 19, 2014 edition of Ophthalmology. Ophthalmology, the official journal of the American Academy of Ophthalmology, publishes original, peer-reviewed reports of research in ophthalmology, including treatment methods, the latest drug findings, and results of clinical trials.
The authors are Chung-Jung Chiu, Paul Mitchell, Ronald Klein, Barbara E. Klein, Min-Lee Chang, Gary Gensler, and Allen Taylor, who represent the following institutions: Tufts University, Boston, Massachusetts; the University of Sydney, Australia; University of Wisconsin School of Medicine and Public Health; and The EMMES Corporation, Rockville, Maryland.
About the Research
In this retrospective study [i.e., examining data and records that were collected in past studies], the authors created the macular risk scoring system (MRSS) to help clinicians in assessing how likely it is that patients may develop age-related macular degeneration (AMD).
Two large AMD data sets, the Age-Related Eye Disease Study (AREDS) and the Blue Mountains Eye Study (BMES), were utilized to identify crucial parameters for the study, and five demographic predictors (age, sex, education level, race, smoking status) and three ophthalmic predictors (presence of pigment abnormality, soft drusen, and maximum drusen size) were identified.
[Editor's note: Drusen are the hallmark of "dry" AMD. Drusen are small yellow deposits beneath the retina that are a buildup of waste materials, composed of cholesterol, protein, and fats. They are a risk factor for progressing to vision loss.]
This is the first risk scoring system that also uses incidence data to help predict risk up to 10 years in the future. The authors also provide specificity and sensitivity for various cutoffs, providing flexibility for users. Limitations are mostly based on the limitations of BMES and AREDS, which include limited number of AMD cases and a narrow study population, respectively.
Overall, the MRSS provides a valuable tool to assess whether patients are low or high-risk, allowing the physician to alter monitoring as needed.
About the Blue Mountains Eye Study (BMES)
The longitudinal Blue Mountains Eye Study (BMES), named after the Australian mountain range, is the first large population-based assessment of visual impairment and common eye diseases of a representative sample of older Australians. A longitudinal study follows, and gathers information about, the same individuals or group of people over an extended period of time – often many decades.
The ongoing BMES began in 1992-1993, with the recruitment of 3,654 people aged 50 and older. Follow-up exams were conducted in 1997-1999 (5-year), 2002 (10-year) and 2007-2009 (15-year). You can read more about the BMES at the University of Sydney's Centre for Vision Research.
About the Age-Related Eye Disease Study (AREDS)
The Original AREDS Trial
The original Age-Related Eye Disease Study (AREDS), launched in 1992, was a major clinical trial sponsored by the National Eye Institute to (a) learn more about the history of, and risk factors for, age-related macular degeneration (AMD) and cataract and (b) evaluate the effect of high doses of antioxidants and zinc on the progression of AMD and cataract.
The original AREDS trial involved 4,757 participants, age 55-80 at the time of enrollment. Of 4,203 surviving participants, 3,549 (about 84 percent) took part in the follow-up AREDS2 trial.
The Second AREDS Trial (AREDS2)
In May 2013, The National Eye Institute concluded the Age-Related Eye Disease Study 2, which tested several changes to the original AREDS formulation. The ongoing AREDS trials have produced a number of breakthrough discoveries, including last year's clarification of the role of supplements in preventing advanced AMD.
A Research Summary from Ophthalmology
From the article abstract:
Design: The Age-Related Eye Disease Study (AREDS) cohort followed up for eight years served as the training data set, and the Blue Mountains Eye Study (BMES) cohort followed up for 10 years served as the validation data set.
Participants: A total of 4,507 AREDS participants (contributing 1,185 affected vs. 6,992 unaffected eyes) and 2,169 BMES participants (contributing 69 affected vs. 3,694 unaffected eyes).
Methods: We used eight baseline predictors—age, sex, education level, race, smoking status, and presence of pigment abnormality, soft drusen, and maximum drusen size—to devise and validate a macular risk scoring system (MRSS). We assessed the performance of the MRSS by calculating sensitivity, specificity, and … c-index.
Results: The internally validated AREDS and the externally validated BMES suggested excellent performance of the MRSS. An application for the iPhone and iPad also was developed as a practical tool for the MRSS.
Conclusions: The MRSS was developed and validated to provide satisfactory accuracy and generalizability. It may be used to screen patients at risk of developing advanced AMD.
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