The high-resolution imaging technique of spectral-domain optical coherence tomography (SD-OCT) at a single time point may help guide therapy decisions among patients with multiple sclerosis (MS). Study researchers found that lower baseline ganglion cell-inner plexiform layer (GCIPL) thickness on SD-OCT is independently associated with long-term disability worsening in MS, according to study findings published in Neurology.
Because studies to date on employing SD-OCT measurements to predict disability have had no more than 5 years of follow-up, study researchers sought to double the follow-up period and discover whether accuracy in predictions was maintained.
They prospectively studied patients with MS between September 2008 and March 2020. The patients underwent an SD-OCT scan within 6 months of baseline Expanded Disability Status Scale (EDSS) assessment and repeated the EDSS assessment at least 7 years later.
A subset of participants underwent baseline and follow-up assessments of visual acuity at 100%, 2.5%, and 1.25% contrast and another subset underwent SD-OCT assessment at least 7 years after their first SD-OCT scan. Patients who used glasses or contact lenses wore them during testing.
The 132 participants with MS were categorized into 2 groups based on whether the average GCIPL thickness of their eyes was less than the mean GCIPL thickness of all eyes at baseline, 70 µm, or whether it was 70 µm or greater. Only patients with eyes without a history of optic neuritis were included in comparisons of demographic and clinical characteristics.
Patients with an average GCIPL thickness of less than 70 µm were more likely to have a longer disease duration than their counterparts (10.9±8.9 vs 6.9±6.8 years, respectively; P =.007). The study researchers also encountered more follow-up on intermediate-potency disease-modifying treatments (DMTs) in patients with less GCIPL thickness (16% vs 9%, respectively; P <.001).
In multivariable analyses, patients in the group with greater baseline GCIPL thickness experienced greater annualized increases in raw EDSS scores during follow-up than their counterparts (β, 0.06; 95% CI, 0.002-0.11; P =.043).
Excluding eyes with prior optic neuritis, findings indicated that the group with less GCIPL thickness experienced almost 4 times greater odds of EDSS worsening (adjusted odds ratio (AOR), 3.97; 95% CI, 1.24-12.70; P =.02) and nearly 3 times greater odds of low-contrast visual acuity worsening (AOR, 2.93; 95% CI, 1.40-6.13; P =.04) than the group with greater GCIPL thickness.
When the study researchers sorted the data into 3 groups (baseline GCIPL thickness <70µm in both eyes, n=41; patients with a baseline GCIPL thickness <70µm in 1 eye and ≥70µm in the fellow eye, n=21 patients; and patients with a baseline GCIPL thickness ≥70µm in both eyes, n=45), the group with less GCIPL thickness in both eyes were at more than a 5-fold increased odds of EDSS worsening compared with the group with the greater GCIPL thickness in both eyes (AOR, 5.03; 95% CI, 1.27-19.83; P =.021).
Limitations of the study included the exclusion of eyes with a history of optic neuritis, the weaknesses inherent in EDSS (inter-rater variability and low sensitivity to change), the small size of the cohort, and the possibility of selection bias due to open cohort design.
The study researchers concluded, “Lower baseline GCIPL thickness on SD-OCT is independently associated with long-term disability worsening in MS. Accordingly, SD-OCT at a single time-point may help to guide therapeutic decision making among individual [people with multiple sclerosis].”
Disclosure: Multiple authors declared affiliations with the pharmaceutical industry. Please refer to the original article for a full list of disclosures.
Lambe J, Fitzgerald KC, Murphy OC, et al. Association of spectral-domain OCT with long-term disability worsening in multiple sclerosis. Neurology. Published online March 2, 2021. doi:10.1212/WNL.0000000000011788