Retinal thinning differentiates treatment effects in relapsing multiple sclerosis below the clinical threshold.

OBJECTIVE

To investigate retinal layer thinning as a biomarker of disease-modifying treatment (DMT) effects in relapsing multiple sclerosis (RMS).

METHODS

From an ongoing prospective observational study, we included patients with RMS, who (i) had an optical coherence tomography (OCT) scan within 6 to 12 months after DMT start (rebaseline) and ≥1 follow-up OCT ≥12 months after rebaseline and (ii) adhered to DMT during follow-up. Differences between DMT in thinning of peripapillary-retinal-nerve-fiber-layer (pRNFL) and macular ganglion cell-plus-inner plexiform-layer (GCIPL) were analyzed using mixed-effects linear regression. Eyes suffering optic neuritis during follow-up were excluded.

RESULTS

We included 291 RMS patients (mean age 30.8 years [SD 7.9], 72.9% female, median disease duration 9 months [range 6-94], median rebaseline-to-last-follow-up-interval 32 months [12-82]). Mean annualized rates of retinal layer thinning (%/year) in reference to DMF (n = 84, GCIPL 0.28, pRNFL 0.53) were similar under TERI (n = 18, GCIPL 0.34, pRNFL 0.59), GLAT (n = 24, GCIPL 0.32, pRNFL 0.56), and IFNb (n = 13, GCIPL 0.33, pRNFL 0.60) were slightly lower under S1PM (n = 27, GCIPL 0.19, pRNFL 0.42) and CLA (n = 23, GCIPL 0.20, pRNFL 0.42), and were significantly lower under NTZ (n = 47, GCIPL 0.09, pRNFL 0.24; both p < 0.001) and antiCD20 (n = 55, GCIPL 0.10, pRNFL 0.23; both p < 0.001). In patients achieving NEDA-2, observed thinning rates were lower overall, but still significantly lower under NTZ and antiCD20.

INTERPRETATION

Applying a rebaselining concept, retinal layer thinning differentiates DMT effects even in clinically stable patients and, thus, might be a useful biomarker to monitor DMT efficacy on subclinical neuroaxonal degeneration-at least on a group level.