Registry‐based definition of neovascular age‐related macular degeneration in Denmark: A nationwide multicentre validation study

PURPOSE: Neovascular age-related macular degeneration (AMD) is a common chronic disease with substantial societal impact. The validity of approaches to identify neovascular AMD in the Danish National Patient Registry (DNPR) remains uncertain. We evaluated the accuracy of different registry-based definitions for identifying patients with neovascular AMD. METHODS: Patients with and without neovascular AMD were identified through medical record review at hospital-based ophthalmology departments and private practice ophthalmologists across all five Danish regions. Three registry-based definitions were evaluated: Model 1: ICD-10 H353J or H353K; Model 2: H353J or H353K combined with either of the intravitreal procedure codes KCKD05 or KCKD05B; Model 3: H353 or H353J or H353K combined with either of the intravitreal procedure codes KCKD05 or KCKD05B. Sensitivity, specificity, and accuracy were calculated using medical record review as the reference standard. Analyses were performed overall and stratified by hospital-based ophthalmology departments and private practice ophthalmologists. RESULTS: We included 571 individuals (306 with and 265 without neovascular AMD). All three definitions demonstrated >90% sensitivity, specificity, and accuracy overall. H353 or H353J or H353K combined with an intravitreal procedure code had the highest observed sensitivity and accuracy (sensitivity 98.0%, specificity 98.9%, and accuracy 98.4%). Stratified analyses demonstrated high diagnostic validity in both hospital-based ophthalmology departments and private practice ophthalmology clinics. CONCLUSION: Registry-based definitions of neovascular AMD in the DNPR demonstrated high diagnostic validity overall and across both hospital-based and private ophthalmology settings. H353 or H353J or H353K combined with an intravitreal procedure code provided the highest sensitivity and accuracy while maintaining high specificity, suggesting that this definition may reduce under-ascertainment of treated neovascular AMD in contemporary Danish registry-based studies.