Positive News on the AMD Front: Prevalence Down

Prevalence of AMD May be Declining

In 2004, the Eye Diseases Prevalence Group, using a meta-analysis of regional population-based studies, estimated that late AMD was present in more than 1.75 million people in the US. They also projected that the number with AMD would increase to almost 3 million by 2020, since Americans are living longer.

Those projections didn’t take into account the effects of changes in treating people at high risk for late AMD, such as more frequent recommendations for the use of zinc and antioxidant vitamins following publication of results from the AREDS trial in 2001. The predictions also assumed that AMD risk factor rates would remain unchanged.

More recently, another study forecast that the number of people with early AMD would jump from 9.1 million to 17.8 million, and that late AMD would go from 620 000 to 1.6 million over the next 40 years, owing to the aging of our population.

Now, an updated estimate (1) based on the 2005-2008 National Health and Nutrition Examination Survey (NHANES) tells us that AMD prevalence has actually declined since the last report (1988-1994 NHANES).

Study Design

Retinal photographs (45° digital images) from both eyes of more than 5,500 people 40 and older from the 2005-2008 NHANES were graded for severity using a standard protocol, with AMD as the main outcome.

Results

Overall, the prevalence of any AMD was 6.5%, which is considerably lower than the 9.4% prevalence reported in the 1988-1994 NHANES. The prevalence of large and soft drusen, RPE de-pigmentation, increased retinal pigment, exudative macular degeneration, geographic atrophy, and early / late AMD are shown in Table 2 below.

Comments

This study estimates that about 1 in 15 people over 40 – 7.2 million Americans in all – have AMD. In addition to a greater number of at risk people taking AREDS supplements, the authors speculate that reductions in smoking and cholesterol levels, and/or improvements in diet, exercise and blood pressure may have contributed to the decrease in prevalence.

Currently, however, adults and children are more overweight than ever, and a large portion of Americans fail to meet dietary recommendations. 2011 is also the year that the first wave of baby boomers will turn 65 – at the rate of 7000 per day. So it’s important to delve deeper and try to understand why the drop in AMD prevalence occurred. If we can better understand what’s behind the decline, it might provide insights to help prevent future generations from developing this disease.

Reference

1. Klein R, et al. Prevalence of ARMD in the US Population. Arch Ophthalmol 129:75-80, 2011.