Inflammatory Markers and Disease Progression in Moderate-Stage Retinitis Pigmentosa: Longitudinal Analysis from the Retinitis Pigmentosa Progression and Inflammatory Marker Registry Study

To investigate longitudinal changes in visual functional and structural measures and to evaluate whether inflammatory markers are associated with disease progression in patients with moderate-stage retinitis pigmentosa (RP). Multicenter 24-month prospective cohort study (RP-PRIMARY [Retinitis Pigmentosa Progression and Inflammatory Marker Registry]); longitudinal analysis. Sixty-seven patients aged 20-70 years with typical moderate-stage RP; 66 patients completed 24-month follow-ups. ETDRS best-corrected visual acuity (BCVA), Humphrey Field Analyzer 10-2 perimetry, OCT, and fundus autofluorescence (AF) were assessed longitudinally. Aqueous flare and systemic inflammatory markers (interleukin 8 [IL-8], intermediate monocyte proportion, and high-sensitivity C-reactive protein [hs-CRP]) were measured annually. Longitudinal changes in functional and structural outcomes were evaluated using linear mixed-effects models. Associations between baseline inflammatory markers and disease progression were assessed using linear mixed-effects models, adjusted for age, sex, intraocular lens status, and baseline ellipsoid zone (EZ) vertical length. Annual rates of change in visual functional and structural measures and their associations with inflammatory markers. Over the 24-month follow-up period, ETDRS BCVA, mean deviation, central retinal sensitivity, EZ length, central foveal thickness, and AF ring area all showed significant progression. Higher baseline aqueous flare was associated with faster decline in central 12-point mean retinal sensitivity and EZ vertical length. Higher baseline intermediate monocyte proportion and hs-CRP were associated with faster ETDRS BCVA decline. Conversely, higher aqueous flare and intermediate monocyte proportion were associated with slower AF ring constriction, while higher hs-CRP was associated with slower central foveal thinning. No significant longitudinal associations were observed for IL-8. Visual functional and structural measures demonstrated significant progression over 2 years in moderate-stage RP. Baseline aqueous flare, intermediate monocyte proportion, and hs-CRP were associated with disease progression, supporting their potential as exploratory biomarkers for identifying patients at risk of faster progression. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.