A new study by researchers at Unity Health, Sunnybrook Health Sciences Centre and the University of Toronto has found that patients with a diabetes-related eye condition who are male, Black or Hispanic, or live farther from a treatment centre are more likely to miss follow-up appointments, putting them at greater risk of vision loss.
Published in JAMA Network Open, the research aims to inform strategies to help retain patients in care and better manage their diabetic retinopathy - the most common cause of vision loss among people with diabetes. Caused by high blood sugar damaging the retina, the condition affects an estimated one in four Canadians with diabetes and can lead to complications such as abnormal blood vessel growth and diabetic macular edema, where blood vessels in the retina leak fluids - both of which can result in vision loss.
Treatments aim to prevent vision loss by stopping blood vessel growth and reducing leakage in the retina, using either laser therapy or anti-VEGF (vascular endothelial growth factor) drug injections.
"For both treatments, you need consistent treatment and follow-up," says Ryan Huang, a third-year medical student at U of T's Temerty Faculty of Medicine who was the study's first author.
From left: Ryan Huang, Marko Popovic, Radha Kohly and Rajeev Muni (supplied images)
Under the mentorship of Marko Popovic, a medical retina specialist at Unity Health Toronto's St. Michael's Hospital, Huang collaborated with Radha Kohly and Rajeev Muni to investigate the sociodemographic and clinical factors linked to being "lost to follow-up." Kohly is a medical retina specialist at Sunnybrook Health Sciences Centre while Muni is vitreoretinal surgeon at St. Michael's Hospital. Both are associate professors of ophthalmology and vision sciences at Temerty Medicine.
For the study, the researchers analyzed electronic medical record data for 2,961 patients treated by Kohly and Muni from January 2012 to December 2021. Patients were classified as lost to follow-up if they received a treatment but did not return to see their specialist in the one-year period following their last appointment.
"We found that 17 per cent of patients were lost to follow-up over the 10-year study period," says Huang.
Of those, 41 per cent were permanently lost to follow-up - meaning they never returned to the clinic - and 54 per cent came back at some point after one-year period.
The researchers found that patients who are male or Hispanic were 20 to 50 per cent more likely to be lost to follow-up, while Black patients were twice as likely to experience significant gaps in care. Patients living more than 20 kilometres from the treatment centre were also at higher risk, with the likelihood of missing follow-up appointments increasing as the distance grew.
Conversely, patients with worse baseline vision or diabetic macular edema were less likely to be lost to follow-up. "These patients with more severe disease require more intensive treatment regimens and this may incentivize them to pursue regular follow-up because they're seeing the greatest improvements in their vision," says Huang.
The researchers also found that patients who received laser treatments were more likely to miss follow-ups than those who received anti-VEGF drug injections. Huang notes that while the effects of laser treatments are last longer, skipping follow-up care may leave patients at higher risk of worsening vision later on.
"Monitoring is absolutely necessary to preserve their long-term vision," he says.
For patients who were temporarily lost to follow-up, the researchers' preliminary results show that patients who returned to the clinic to resume treatment after a gap experienced significantly worse vision. And while patients who received laser treatments saw their eyesight return to pre-treatment levels, those treated with anti-VEGF injections never fully regained their vision after restarting follow-up care.
"If you have a patient who is at high risk of being lost to follow-up based on the characteristics we've identified, you may choose laser treatment since they're more likely to obtain a full recovery in their vision," says Huang.
The findings were recently presented at the Canadian Ophthalmological Society annual meeting.
In addition to highlighting the importance of follow-up care in managing diabetic retinopathy, the researchers also suggest several approaches to prevent patients from being lost to follow-up. These include using automated text messages and phone calls as reminders for upcoming appointments, creating culturally and linguistically tailored patient education resources, and co-ordinating appointments with transportation services to make it easier for patients who live farther away.
"This is an ophthalmology study, but we believe it's widely applicable to all chronic diseases that require regular follow-up and management," Huang says.
