Characteristics of Study Design and Statistical Analysis in OCT-Based Studies of Neurodegeneration

To evaluate the design and statistical analysis of recently published clinical studies of retina OCT of neurodegenerative diseases.

Review of 134 publications.

Clinical and translational publications from 2013-2023 involving human OCT studies were reviewed. Publications were restricted to the top 10 journals of either ophthalmology or neurology based on the SCImago Journal Rank. Data were extracted and analyzed regarding study design characteristics, disease studied, imaging characteristics, and statistical analysis method.

Characteristics of study design and statistical analysis.

Of the 134 studies, the most commonly investigated diseases were multiple sclerosis (47.8%), Alzheimer disease (31.3%), and Parkinson disease (14.2%). One hundred three (76.9%) studies were cross-sectional, and 31 (23.1%) studies were longitudinal. Of the 42 Alzheimer disease studies, 19.0% used cerebrospinal fluid biomarkers, 26.2% used positron emission tomography imaging, and 4.8% used genetic data to confirm the diagnosis. The peripapillary retinal nerve fiber layer thickness (95 studies) and macular retina layer thickness (96 studies) were the most commonly studied OCT measurements; 69 studies looked at both of these measurements. For 25 (18.7%) of the studies, no statement of image quality criteria or exclusion of subjects or eyes because of image quality criteria was identified. One hundred seventeen (87.3%) studies performed bilateral eye imaging, but only 89 (66.4%) studies performed bilateral image analysis. Of the 89 studies with bilateral eye image analysis, 53 (59.6%) performed analysis at the eye level by combining data from the left and right eye, making each eye (rather than each subject) the unit of analysis. Of the 53 studies performing analysis at the eye level for data from both eyes, the intereye correlation was adjusted in 38 (71.7%) studies, while 15 (28.3%) studies did not account for the intereye correlation. Thirty-seven (27.6%) studies corrected for multiple comparisons.

There may be opportunities for improvement in the study design and statistical analysis of OCT studies of neurodegenerative diseases.

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.