Reflux Extension Index (REXI) as a novel ordinal tool for quantifying saphenous reflux burden in women with CEAP...

To describe and quantify saphenous reflux patterns in women with early chronic venous disease (CEAP C1 and C2), to evaluate its discriminative ability between C1 and C2 and to identify if a greater extension of saphenous reflux corresponds to a greater probability of C2 classification.

Cross-sectional study of women ≥ 18 years classified as CEAP C1 or C2 by clinical examination and duplex ultrasonography between January 2019 and July 2023 at a private phlebology clinic. Met inclusion criteria 1,138 (2,276 limbs); all examinations were performed by a single operator. The Number of Zones with Reflux (NZR; 0-12 - Pittaluga's lower-limb mapping) was binned into REXI-0 (0), REXI-1 (1-2), REXI-2 (3-5), REXI-3 (≥ 6). Analyses were conducted at the limb level (n = 2,276) and at the patient level for concordant subgroups (bilateral C1 n = 666; bilateral C2 n = 240; total n = 906). Logistic regression, adjusted for age and family history, was performed in 885 women with complete data. Model discrimination was assessed using the area under the receiver operating characteristic curve (AUROC), monotonic trend within a generalized estimating equations (GEE) framework, and McNemar's test.

At the limb level, C2 prevalence increased monotonically with REXI category. At the patient level, adjusted odds ratios for bilateral C2 versus REXI-0 were 5.26 (95% CI 3.34-8.29), 14.93 (9.31-23.95), and 51.97 (25.53-105.81) for REXI-1 to -3 (all p < 0.001; McFadden pseudo-R² = 0.280). Discrimination was good and improved with adjustment: crude AUROC 0.815 (0.783-0.847), adjusted 0.837 (0.805-0.868); Δ AUROC = +0.022, p = 0.001. The adjusted probability of C2 crossed 50% between REXI-1 and REXI-2 (56.6%, 48.3-64.9). A left-sided C2 predominance was observed (McNemar OR 1.34, 1.04-1.74; p = 0.026). Of 240 women with bilateral C2, 101 (42.1%) had a REXI-0/REXI-1 profile - minimal or no saphenous reflux.

REXI is a simple, quantitative, and clinically applicable ordinal framework for measuring saphenous reflux extension in women with early chronic venous disease. Prospective multicentre validation and interventional outcome studies are the necessary next steps.