Aim: To create a classification system for severe, rare, and progressive genetic conditions for use in research reporting. Method: A modified Delphi consensus technique was used to create and reach agreement on a new system of condition categories. Interrater reliability was tested via two rounds of an online survey whereby physicians classified a subset of conditions using our novel system. Overall percentage agreement and agreement above chance were calculated using Fleiss’ kappa (κ). Results: Eleven physicians completed the first Delphi, with an overall agreement of 76.4%, the κ value was 0.57 (95% confidence interval 0.51–0.63), indicating moderate agreement (0.41–0.60) above chance. Based on the first survey several categories were described in more detail. The second survey confirmed a classification system with 12 categories, with an overall percentage agreement among the participants of 82.6%. The overall mean κ value was 0.71 (95% confidence interval 0.65–0.77), indicating substantial agreement (0.61–0.80). Interpretation: Our new system was useful in categorizing a broad range of rare childhood diseases and may be applicable to other rare disease studies; further validation in larger cohorts is required. What this paper adds: This novel 12-category classification system can be used in research reporting in rare and progressive genetic conditions.
van Karnebeek, C. D. M., Beumer, D., Pawliuk, C., Goez, H., Mostafavi, S., Andrews, G., ... Siden, H. (2019). A novel classification system for research reporting in rare and progressive genetic conditions. Developmental Medicine and Child Neurology, 61(10), 1208-1213. https://doi.org/10.1111/dmcn.14180