According to a report published Online First by Archives of Ophthalmology, one of the JAMA/Archives journals, a new risk assessment model may help predict the development of advanced age-related macular degeneration.
The article’s background information states age-related macular degeneration (AMD) to be a leading cause of blindness in the U.S. and in the Western world. The authors write,
“As progress in designing better preventive measures and earlier treatment options accelerates and new gene associations are identified that add to currently known risk factors, the desirability of having a reliable risk assessment model has become of considerable interest and potential value.”
They continued to explain that the model should recognize individuals with early AMD who possess the largest risk of developing advanced AMD with the ability to predict when that progression might occur. Michael L. Klein, M.D., from the Casey Eye Institute, Oregon Health & Science University, Portland, and his fellow investigators wanted to design a risk assessment model for development of advanced AMD that included phenotypic (related to observable physical characteristics), demographic, environmental and genetic risk factors.
The investigators utilized longitudinal data from the Age-Related Eye Disease Study, including participants’ DNA samples, ocular and medical histories and examinations. The study was conducted by following patients for an average of 9.3 years and was categorized into two groups. The first group of participants who had developed advanced AMD in either eye and who did not have this condition at baseline. The second group consisted of participants who developed advanced AMD in a second eye who already had the condition in one eye at baseline.
The final model included the following variables: a simple scale score (a sum of clinical risk factors in both eyes), two genotypes, very large drusen (deposits on the retina associated with AMD), smoking, family history, advanced AMD in one eye and age.
The final model consisted of 2,692 participants who, at baseline, had no advanced AMD, 635 participants (24%) developed advanced AMD during follow-up. 82 percent of patients with advanced AMD at baseline had the geographic atrophy (gradual deterioration of retinal cells, called “dry AMD”) type, while 56 percent who had the neovascular type (new blood vessel formation and leakage, called “wet AMD”) developed advanced AMD in the other eye.
The study therefore suggests that the complete model appeared to perform well and discriminated an individual’s risk of advanced AMD.
The authors state,
“The results can be of potential value in clinical practice by helping determine the frequency of follow-up examinations, the use of home monitoring of central vision, and the advisability of initiating preventive measures including beneficial lifestyle changes such as dietary alterations and nutritional supplement use. The short-term end points (e.g., 2 years) may be helpful in planning clinical trials.”
They continued saying that the model performed well on measures of discrimination, calibration and overall performance and added,
“We believe our current model is of substantial value in assessing AMD risk, and we expect that future advances will further improve its accuracy.”
Written by Grace Rattue