Preventive Steps May Lower AMD Costs
Preventing Age-Related Macular Degeneration (AMD) and delaying its progression would best preserve people's quality of life while containing health care system costs. The results from two new analyses suggest that adopting dietary habits or using supplements that slow progression from early to late stages, could ease the future burden of this disease.
Combined Dietary Factors Reduce AMD Risk
Foods provide many nutrients that may interact to modify the risk for AMD. Therefore, instead of looking at isolated nutrients, researchers from Tufts University developed a composite scoring system to examine the combined effect of dietary nutrients on AMD risk.
Study Design and Results
Data was analyzed for 4,003 Age-Related Eye Disease Study (AREDS) participants, involving 7,934 eyes. Levels of AMD-protective nutrients, including vitamins C and E, zinc, lutein, zeaxanthin, omega-3 fatty acids (DHA and EPA), as well as low-GI (Glycemic Index) foods, were assessed using participants' food intake reports. Each dietary factor was assigned a percentile score, and factor scores were added up to find each participant's compound score. Compound scores were related to participants' AMD risk, based on stereoscopic fundus photographs of the macula taken when they joined AREDS.
Participants whose diets included higher levels of these protective nutrients and of low-GI foods were at substantially lower risk for early and advanced AMD. Validation analyses showed the relationships to be robust.
Conclusion and Comments
The results suggest that the compound score summarizing the overall effect of diets rich in the AREDS trial nutrients (vitamin C, vitamin E, and zinc), the AREDS 2 trial nutrients (DHA, EPA, lutein and zeaxanthin), and low-GI foods are independently associated with lower risk for prevalent drusen and advanced AMD. Beta-carotene did not affect risk levels. The findings are in accord with earlier research linking low GI-diets with reduced risk of AMD and cataract, and further research is warranted.
New Therapies May Mitigate Rise in AMD
The Vision Health Cost-Effectiveness Study Group - encompassing investigators from the CDC, the National Center for Chronic Disease and Prevention and other institutions - report that while the prevalence of AMD will increase substantially by 2050, the use of new therapies can mitigate its effects.
Study Design and Results
The study simulated cases of early AMD, choroidal neovascularization (CNV), geographic atrophy (GA), and AMD-attributable visual impairment and blindness with five possible scenarios:
| ||(1) No treatment; |
(2) Focal laser and photodynamic therapy (PDT) for CNV;
(3) Vitamin prophylaxis at early-AMD incidence with focal laser/PDT for CNV;
(4) No vitamin prophylaxis followed by focal laser treatment for extra and juxtafoveal CNV and anti-vascular endothelial growth factor treatment;
(5) Vitamin prophylaxis at early-AMD incidence followed by CNV treatment, as in scenario .
Cases of early AMD nearly doubled, increasing from 9.1 million in 2010 to 17.8 million in 2050 across all scenarios. In non-vitamin-receiving scenarios, cases of CNV and GA increased from 1.7 million in 2010 to 3.8 million in 2050 (25% lower in vitamin-receiving scenarios). Cases of visual impairment and blindness increased from 620,000 in 2010 to 1.6 million in 2050 when given no treatment and were 2%, 22%, 17%, and 35% lower in scenarios 2, 3, 4, and 5, respectively (see Figure 2E).
Number of Americans with pre-vision-threatening age-related macular degeneration (AMD) and blindness, with 5 alternative treatment scenarios from 2010 to 2050. Scenario 1 indicates no treatment (baseline); scenario 2, focal laser or photodynamic therapy (PDT) for CNV; scenario 3, universal vitamin prophylaxis at early AMD incidence with focal laser or PDT for CNV treatment; scenario 4, no vitamin prophylaxis followed by focal laser treatment for extrafoveal and juxtafoveal CNV and anti-vascular endothelial growth factor (anti-VEGF) treatments for subfoveal CNV for 2 years followed by PDT; scenario 5, universal vitamin prophylaxis followed by focal laser and anti-VEGF treatments for subfoveal CNV for 2 years followed by PDT.
Conclusion and Comments
The authors found that use of vitamins and existing therapies could reduce AMD by as much as 35%, translating to 565,000 fewer cases of visual impairment and blindness in 2050.
A 23% reduction in cases of visual impairment and blindness could be achieved using only vitamin prophylaxis in conjunction with focal laser and PDT therapies for patients who develop CNV - which amounts to a reduction of 375,000 cases of visual impairment and blindness five decades from now.
According to the authors, additional efforts to expand the use of AREDS level dietary supplements Is a cost-effective method of delaying AMD progression and cost-effective use of health care resources. However, research indicates it is not widely used among patients with early-stage disease and the correct dosage is seldom used. For example, though 68% of patients with early AMD who visited a retinal specialty practice in Edmonton, Canada, took some form of AREDS-recommended antioxidant supplement, no patients were taking the correct dosage of all 4 recommended vitamins. Public prevention efforts should focus on expanding the use of antioxidant vitamins in people with early AMD, and ensuring that these patients use the correct dosage.
- Chiu, C-J, et al. Dietary compound score and risk of age-related macular degeneration in the AREDS. Ophthalmology 116:939-46, 2009.
- Rein DB et al. Forecasting age-related macular degeneration through the year 2050: the potential impact of new treatments. Arch Ophthalmol 127:533-40, 2009.