Hypertensive retinopathy: comparing the Keith-Wagener-Barker to a simplified classification

Purpose: This study assessed the interobserver and intraobserver grading reliability of the Keith-Wagener-Barker (KWB) system to the proposed Mitchell-Wong 'simplified' three-grade classification for hypertensive retinopathy. Methods: Digital retinal images of normal and hypertensive human fundii (n = 50 per group) were randomly graded by an optometrist and an ophthalmologist using the two systems. Interobserver agreement was compared to a 'gold standard' research grader. Intraobserver agreement was assessed through a repeat grading after 6 months. Cohen's kappa coefficients were used to assess the degree of agreement. Results: Both clinicians demonstrated a good level of agreement with the KWB and simplified classification compared with a 'gold standard' grader; there was no significant difference in the level of agreement for either of the two classification methods for either observer. The simplified classification was found to be equally as efficacious as the KWB system with respect to interobserver and intraobserver agreement for both practitioners. Conclusion: These findings indicate that the simplified classification of hypertensive retinopathy is both reliable and repeatable. The advantage of the simplified method over the KWB system in correlating retinal microvascular signs to incident cardiovascular risk supports its adoption in clinical practice.