Catering to the Era of Gene Therapy: An Objective Staging Strategy for Bietti Crystalline Dystrophy using Principal Component Regression

Abstract

Purpose

To devise a novel and objective staging strategy of Bietti crystalline dystrophy (BCD) for gene therapy.

Design

Development and validation of severity and staging assessments.

Methods

We screened out 127 BCD patients from a cohort of 2146 patients with inherited retinal diseases (IRDs). Our study analyzed 6 critical indicators: age, LogMAR BCVA, absent autofluorescence (AF) area, mottled AF area, and average retinal thickness in ETDRS 1 mm circle and 3 mm ring. Using Principal Component Regression (PCR), we developed a quantitative model termed the Bietti Crystalline Dystrophy Score for Severity Assessment (BCD-SA Score), integrating indicators for disease severity. Additionally, a corresponding staging system (BCD-SA Stage) was derived from this model. We assessed the efficacy of the BCD-SA Stage, comparing it to the traditional staging strategy through a paired-sample t-test and Cohen's Kappa (κ) for agreement evaluation.

Results

The patients’ mean age was 47.96 ± 10.1 years. Spearman correlation analysis and univariate linear regression demonstrated a strong correlation between all indicators and the disease stages defined by the traditional method (P < .001). Principal Component Analysis (PCA) addressed the multicollinearity among indicators, extracting 2 linear uncorrelated principal components (PCs, Factor 1 and Factor 2). These PCs were then used in a multiple linear regression model to develop the BCD-SA Score. Subsequently, a novel and objective staging system (BCD-SA Stage) was created, providing a more precise disease delineation.

Conclusions

We developed an innovative and objective scoring and staging strategy for BCD by integrating 6 variables and utilizing the PCR approach. This strategy advances BCD assessment and serves as a benchmark for the natural history evaluation and staging of other IRDs.