Socioeconomic and clinical factors associated with genetic testing completion in Stargardt disease

Genetic testing (GT) is crucial for Stargardt disease (STGD) diagnosis and clinical trial (CT) eligibility; however, predictors of GT completion remain understudied. We identified factors associated with GT completion and characterized CT participation among genetically confirmed patients.

We retrospectively reviewed 280 patients with clinically diagnosed STGD who were evaluated at a US tertiary referral center (2003-2024). Multivariable logistic regression was used to identify predictors of GT completion.

Among 280 participants, 246 (88%) completed GT. GT completion was significantly less likely in participants who were Black (odds ratio [OR]: 0.40, 95% CI: 0.16-0.98), under/uninsured (OR: 0.47, 95% CI: 0.19-0.97), without genetic counseling (GC) (OR: 0.09, 95% CI: 0.03-0.22), or without reproductive plans (OR: 0.35, 95% CI: 0.14-0.89). Clinical factors (eg, age of onset, visual acuity, and family history) showed no significant associations. Common reasons for noncompletion included loss to follow-up (41%), patient refusal (26%), and awaiting GC (24%). Among 223 ABCA4-positive participants, 45 (20%) enrolled in CTs, with most (91%) completing GC.

Despite high overall GT completion rates, significant racial and socioeconomic disparities exist. GC emerged as the strongest modifiable factor, conferring over 10-fold higher odds of GT completion. Socioeconomic barriers drive testing disparities in STGD, rather than disease severity or clinical characteristics.