Study shows importance of targeted antibody treatment for patients with wet macular degeneration

Reviewed by Kate Anderton, B.Sc. (Editor)Nov 15 2019

Wet age-related macular degeneration (wAMD) is one of the leading causes of blindness in the U.S. Breakthrough treatments come with a steep price tag and treatment burden for the patient, but a new study suggests their benefits to patient health and society top billions of dollars, or more, if adherence could be improved.

This study shows the importance of targeted antibody therapy in transforming the treatment for a leading cause of blindness, namely wet macular degeneration. Understanding the economics underpinning this therapy is also important because it helps us in the health care system quantify how much impact a therapy delivers relative to its cost."

Dr. Mark Humayun, director of the USC Ginsburg Institute for Biomedical Therapeutics and co-director of the USC Roski Eye Institute

Age-related macular degeneration (AMD) affects approximately 11 million individuals in the United States. The wet form of the disease (wAMD), which is caused by the abnormal growth of blood vessels under the retina, progresses rapidly. Symptoms include blurred vision and blind spots, which often lead to legal blindness. While only 10 percent of people with macular degeneration develop the wet form, the symptoms for these patients are much worse -- in the past, wAMD has caused 90 percent of the blindness associated with macular degeneration.

New treatments for wAMD not only prevent further vision loss, but have also been shown to improve vision with the benefits of these innovative treatments lasting for multiple years, according to clinical trials. However, the administration of these treatments is burdensome and requires patients to receive injections in their eye as frequently as every four to eight weeks. Studies have shown more than half of Medicare patients discontinue treatment within the first year due to cost, the inability to get transportation to and from their retina specialists, and fear or discomfort from receiving these injections.

A new economic study, published in JAMA Ophthalmology and conducted by USC researchers at the Schaeffer Center for Health Policy & Economics, the Ginsburg Institute for Biomedical Therapeutics, and the Roski Eye Institute, quantifies the benefits of treatment for wAMD. They found improvements in vision from innovative treatments generated $5.1 to $8.2 billion in patient benefits. This translates to $0.9 to $3.0 billion in societal value (patient benefits minus treatment costs) over three years. Future innovative treatments that lead to improved adherence would generate an additional $7.3 to $15.0 billion in patient benefits, they estimate.

Weighing benefits and burdens of treatment

Treatments for wAMD first came on the market around 2006. Called anti-vascular endothelial growth factor (VEGF), these treatments target the abnormal growth of the blood vessels and have been shown to restore patients' eyesight for many years.

In clinical trials, these treatments were administered to patients monthly via an injection in the eye. However, in practice adherence tends to decline because of the discomfort associated with the eye injections, difficulty in getting to retina specialists for timely care, and cost. To address this burden to the patient, some doctors have modified treatment plans that allow for lower injection frequency, taking into account the patient's documented vision improvements, cost, and burden of administering the treatment.

Taking into account the costs associated with treatment, the researchers modeled treatment scenarios to provide practitioners, patients, and payers with information about the value of anti-VEGF therapy. Their findings quantified the benefits derived from the therapy to individual patients and society.

"We already know these drugs are effective based on clinical data. Our economic model helps translate clinical outcomes into dollar terms so payers and practitioners can quantify the value of treatment to patients rather than focusing on the treatment cost alone," said Karen Mulligan, lead author on the study and a professor at the USC Price School of Public Policy and the USC Schaeffer Center.

Current Treatments Return Value in the Billions, Future Therapies that Improve Adherence May Add Economic Benefit

To build the economic model, Mulligan and her team collected data from published literature on wAMD patients treated with anti-VEGF therapy, translating average documented changes in visual acuity and treatment usage to quality-adjusted life years (or QALYs), a standard measurement in assessments of the value of new health technologies. Based on well-established metrics, the researchers used a model in which a person with perfect vision has a quality of life that is valued at $150,000 for a single year.

The researchers modeled multiple treatment scenarios:

• No injections scenario
• Less frequent injections scenario (patients received approximately eight injections per year)
• More frequent injections scenario (patients received an average of 10.5 injections per year)
• Improved adherence scenario (85 percent of patients initiate therapy and adherence improves)
• Innovation scenarios (based on clinical trial data representing best case scenarios with patients receiving either more or less frequent injections)

The researchers found even under current treatment conditions of less frequent injections, treatment generates over $1 billion for the full population with wAMD in year one and $5.1 billion in year three. With improved adherence, benefits to the patient population were estimated to reach $7.3 to $11.4 billion in year three.

This translates to a benefit to society (patient benefit minus treatment costs) of $0.9 to $3.0 billion across three years in the current treatment scenarios and upwards of over $4 billion in the innovative treatment scenario (i.e., when a drug that leads to better adherence is discovered).

The researchers find innovations to improve treatment adherence could generate an additional $1.2 to $3.7 billion in patient benefit and $59 million to $1.3 billion in societal value compared to current treatment scenarios, highlighting the fact that when patients follow through with necessary treatment, both individuals and society as a whole can reap the rewards.

"Our model scenarios suggest that even though anti-VEGFs provide substantial benefits, a lot is left on the table due to low adherence," said Mulligan. "One limitation in these types of modeling exercises is we often have access to vision data or treatment patterns, but not both (for the same set of patients). Generating more comprehensive and long-run real world data on vision outcomes and treatment patterns would improve our ability to understand the impact of things like adherence on value."