Screening for obstructive sleep apnea in a diabetic retinopathy clinic in a tertiary care center

Purpose: To screen for obstructive sleep apnea (OSA) in patients presenting to diabetic retinopathy (DR) clinic and to correlate its presence with the severity of DR. Methods: A prospective, cross-sectional study of diabetes mellitus patients in retina clinic of a tertiary care referral center, North India (January 2019-March 2020). All were subjected to STOP-Bang Questionnaire and Epworth Sleepiness Scale (ESS) score. Patients at high OSA risk (STOP-Bang score >= 5 and ESS score >= 10) were referred to Department of Otorhinolaryngology (sleep clinic) for polysomnography. Based on Apnea Hypopnea Index (AHI), OSA was graded as mild (AHI = 5-14/h), moderate (AHI = 15-30/h), and severe (AHI >30/h). Statistical analysis was done using three models of outcome measures: (1) "No DR" versus "any DR," (2) "Less severe DR" versus "More severe DR," and (3) "No diabetic macular edema (DME)" versus "DME." Results: Of 362 patients screened, 18 (4.97%) had OSA (11 mild, 5 moderate, and 2 severe). Though OSA did not show a significant association with various outcome measures, patients with moderate-severe OSA had higher odds in developing "any DR" (OR = 7.408; 95% CI = 0.533-102.898), "more severe DR" (OR = 1.961; 95% CI = 0.153-25.215), and "DME" (OR = 2.263; 95% CI = 0.357-14.355), on multiple logistic regression. Conclusion: Ours is the first screening study of OSA in DR patients in India, the diabetes capital of the world. We detected OSA in 4.97% of patients in a DR clinic, with an increased risk of "any DR," "more severe DR," and "DME" in the presence of moderate-severe OSA.