AMD represents a burden for aging populations

ByPaul Mitchell, MD, PhD

Age-related macular degeneration is the leading cause of blindness and visual disability in adults older than 60 years. Of the two forms of AMD, wet AMD, also called exudative or neovascular AMD, is the most severe form, responsible for two-thirds of central vision loss. Dry, or atrophic, AMD is associated with loss of retinal cells.

The principle factor leading to blindness associated with wet AMD is choroidal neovascularization, which is the outgrowth of new, abnormal blood vessels under the retina penetrating Bruch’s membrane and causing fluid leakage. This painless process progresses rapidly and can lead to complete loss of retinal function in the affected area with visual impairment and blindness.

Growing incidence

In 2001, more than 3 million people in France, Germany, Italy, and the United Kingdom had a diagnosis of AMD. The average life expectancy from age 75, which is the average age of onset for neovascular AMD, is around 8 to 10 years. In 2001, there were about 400,000 new cases of AMD diagnosed.¹

In the United States, the prevalence of clinically diagnosed AMD increased substantially from 5.0% to 27.1% of 20,325 Medicare beneficiaries from 1991 to 1999, and the overall increase in prevalence is likely to continue due to population aging.²

Effects on quality of life

AMD has a major effect on independent living and presents a substantial burden in people older than 75 years. A study of patients in France, the United Kingdom and the United States reported that impaired vision was an independent predictor of vision-related quality of life.³ These findings suggested that preserving a minimum level of visual acuity in the worse eye may improve overall quality of life and that severe visual loss in one eye may be extremely detrimental to overall quality of life.

The effects of AMD are far reaching and often include loss of independence. Patients are unable to read, walk, drive and recognize faces as the disease progresses (Figure 1). Clinical depression occurs in up to one third of patients with AMD, and visual impairment can increase the risk of falls and hip fractures.

Figure 1: Complete or partial loss of central vision with AMD

Figure 1. As AMD progresses, patients typically experience a complete or partial loss of central vision. In more severe cases, daily activities such as reading and driving can be compromised.

Cost burden

AMD poses numerous indirect costs to the health care system, including loss of productivity, increased utilization of community support services, and need for earlier nursing home admission. In a population-based study,^4,5 researchers noted a 7% increase in the risk of nursing home placement associated with each line that visual acuity was reduced.

Patients with severe AMD become less independent as the disease worsens and ultimately may become physically disabled, leading to substantial costs. In the United Kingdom, diagnosis, treatment, rehabilitation and vision aids cost of AMD was estimated to be around 100 million euros,¹ while in the United States, the cost has been estimated to exceed $30 billion.

Visual impairment

Loss of independence is directly associated with clinical depression and overall effects on the quality of life. The severity of visual impairment determines the extent of the loss of independence. At 20/50-60, driving privileges are restricted or revoked in some countries, such as the United States. At 20/80, reading large print becomes difficult, and patients are unable to care for dependents. At or worse than 20/200 is the criterion for legal blindness in most counties, while at 20/300 face recognition is nearly impossible. When visual acuity falls to 20/600, reading is impossible, and patients may become disoriented and immobile.

Disability caused by 135 different conditions worldwide were evaluated,⁶ and researchers concluded that vision disorders pose a high burden to patients that is at least at the same level as bipolar disorder, diabetes and cancer (Figure 2).

	% of Total Years Lost to Disability
Cause of Disability	Developed Countries*	Developing Countries*
Respiratory diseases	6.9	4.2
Cardiovascular diseases	6.7	3.3
Vision disorders**	3.0	8.7
Diabetes	2.3	1.1
Cancer	2.4	0.3
Bipolar disorder	2.2	2.5

Figure 2. Vision disorders can be at least as debilitating as diabetes, cancer and bipolar disorder in developed countries, while they can be more debilitating as respiratory and cardiovascular diseases in developing countries.⁶

* Developed countries includes European countries, former Soviet countries, Canada, United States, Cuba, Japan, Australia, New Zealand, Brunei Darussalam and Singapore. Developing countries includes all other countries.
**Vision disorders includes vision loss due to glaucoma, cataracts, macular degeneration and other age-related vision loss.

Since AMD is a serious burden on quality of life and leads to major costs, prompt, effective therapies are needed. Treatments that can slow the progression and ultimately limit the effect of macular scarring from CNV will lead to a better quality of life for patients, their caregivers, and their communities.

References

Bonastre J, Le Pen C, Anderson P, et al. The epidemiology, economics and quality of life burden of age-related macular degeneration in France, Germany, Italy and the United Kingdom. Eur J Health Econ. 2002;3:94-102.

Lee PP, Feldman ZW, Ostermann J, et al. Longitudinal prevalence of major eye diseases. Arch Ophthalmol. 2003;121:1303-1310.

Berdeaux GH, Nordmann JP, Colin E, Arnould B. Vision-related quality of life in patients suffering from age-related macular degeneration. Am J Ophthalmol. 2005;139:271-279.

Wang JJ, Mitchell P, Smith W, Leeder SR. Factors associated with use of community support services in an older Australian population. Aust N Z J Public Health. 1999;23:147-153.

Wang JJ, Mitchell P, Cumming RG, Smith W; Blue Mountains Eye Study. Visual impairment and nursing home placement in older Australians: the Blue Mountains Eye Study. Ophthalmic Epidemiol. 2003;10:3-13.

Mathers CD, Iburg KM, Salomon JA, et al. Global patterns of healthy life expectancy in the year 2002. BMC Public Health. 2004;4:66.

Macugen® is indicated for the treatment of neovascular (wet) age-related macular degeneration.

Macugen is contraindicated in patients with active or suspected ocular or periocular infection or with known hypersensitivity to the active substance or to any of the excipients.

Safety and efficacy of Macugen beyond 2 years have not been demonstrated.

In postmarketing experience, rare cases of anaphylaxis/anaphylactoid reactions, including angioedema, have been observed within several hours after the intravitreal administration procedure, although a direct relationship to Macugen or other factors has not been established.

Three percent of patients experienced a serious adverse event potentially related to the injection procedure. Serious ocular adverse events reported in patients treated with Macugen included endophthalmitis (1%), retinal hemorrhage (<1%), vitreous hemorrhage (<1%), and retinal detachment (<1%).

Following the injection, patients should be closely monitored for endophthalmitis in the 2 weeks following the injection. Patients should be instructed to report any symptoms suggestive of endophthalmitis without delay.

Very commonly (10%) reported ocular adverse events were anterior chamber inflammation, eye pain, increased intraocular pressure (IOP), punctate keratitis, vitreous floaters, and vitreous opacities.

Following the injection, transient increases in IOP were seen in patients treated with Macugen. Therefore, the perfusion of the optic nerve head and IOP should be monitored, and elevation of IOP should be managed appropriately postinjection.