Hopkins Researchers Grow Attendance to Free Eye Care Screens 152% Using Vouchers

When public health experts in east Baltimore, Maryland began offering free eye care services to low-income minority populations, they were perturbed to find that utilization of those services did not increase. Seema Kacker, an MD-PhD candidate at Johns Hopkins School of Public Health, hypothesized that perhaps removing price tags from preventive eye exams had an additional, undesirable effect—could making the service free have removed the perceived value of those services, which led summarily to decreased utilization?

Seema Kacker

Seema Kacker

“A free service is obviously going to decrease the cost, but it can also affect the perceived value of the service,” Kacker said during a presentation at the 2018 meeting of the Association for Research in Vision and Ophthalmology (ARVO). “Under the value discounting hypothesis, offering a service for free might decrease perceived value, and that might lead to a decrease in demand.”

To test her theory, Kacker and colleagues continued to hold eye screens free of charge, but added an extra provision—they began offering vouchers for the services in an effort to boost their perceived value. “The way I thought about this program was that demand for this appointment was determined by both cost and perceived value,” she explained. “If costs [for the eye screening services] are higher, then demand would be lower. But, if perceived value was higher, demand would be higher too.”

In a cluster randomized trial, Kacker and colleagues split about 600 patients with an average age of about 70 years who were 60% women and 76% African American and suspected of having glaucoma into 3 groups. The first group continued to receive notice of free eye care services, and the remaining group was split into 2 subsets — one that received vouchers for free eye screening services, and another that received vouchers for free eye screening services that also included the approximate monetary value of the service ($250).

Follow-up yielded complete data for 431 glaucoma suspects at 1 of 64 screening events. Those referred in the traditional manner had a 49% attendance rate, whereas 67% of individuals who received a voucher without monetary value information, and 62% of individuals who received a voucher with monetary value information presented to the screens.

For a given screening event, offering vouchers without monetary value information increased the odds of presenting for follow-up by 152% (P = .03) compared to not offering a voucher. However, offering vouchers with monetary value information increased the odds of presenting by 112%, but this effect was not significant.

“This begs the question: ‘What is the voucher effect driven by, if not [by estimated value]?’ One is the idea of salience—that the voucher provides something concrete. In a context where we all have very little bandwidth to think about [scheduling,] the voucher might place follow up appointments at the forefront of our minds. It might also decrease procrastination, because there was an expiration date to serve as a reminder.” Kacker said.

Kacker acknowledged several limitations to the study, including potential misinterpretation of the vouchers, since they were distributed by different individuals and thus, could have been explained and perceived differently.

“It’s difficult to get our patients to adhere to our treatment plans. It’s difficult to get them to take their medications. It’s difficult to get them to make follow up appointments and to actually keep them,” Kacker said. “You can see that there seems to be a significant voucher effect here.”

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