Validation of CADS Grading Scale: An Ophthalmic Specific Grading Instrument for Facial Nerve Palsy

Purpose: To evaluate the inter- and intraobserver reliability of the CADS score, a previously described facial nerve grading instrument for ophthalmic grading of facial nerve palsy. Methods: This is a cross-sectional validation study. Two clinicians independently assessed and graded each patient on the same day, masked to each other's grading. Four parameters are assessed in the CADS scale: Cornea (0–3, ±a), static Asymmetry (0–2), Dynamic function (0–3), and Synkinesis (0–2). One clinician reassessed the patients and performed the grading again at a minimum time interval of 1 hour later. A weighted κ analysis was performed to determine inter- and intraobserver reliability using 95% bootstrapped bias-corrected and accelerated (BCa) confidence intervals (CIs). Results: Thirty-three patients (27 women, mean age 51.7, range 23–80 years) with unilateral facial nerve palsy were graded. The overall interobserver reliability was 0.80 (95% BCa CI: 0.68–0.91) for cornea, 0.93 for resting asymmetry (95% BCa CI: 0.55–1.00), 0.80 for dynamic function (95% BCa CI: 0.50–0.96), and 0.88 (95% BCa CI: 0.71–0.96) for synkinesis. The overall intraobserver reliability was 0.93 for cornea (95% BCa CI: 0.83–0.98), 0.82 for resting asymmetry (95% BCa CI: 0.53–0.96), 0.92 for dynamic function (95% BCa CI: 0.72–1.00), and 0.98 for synkinesis (95% BCa CI: 0.84–1.00). Conclusion: The CADS grading scale demonstrates good interobserver reliability and very good intraobserver reliability. It incorporates all ophthalmic complications for facial nerve palsy and remains easy to use and refer to.