GCC Hereditary Angioedema Patient Flow Model

Two independent methods size the GCC HAE population, and they disagree for a specific, sourced reason. The epidemiology method applies HAE's global background prevalence, roughly 1 in 50,000, to the GCC's population of approximately 75 million, implying 1,200 to 1,500 true patients. The registry method counts patients actually identified in clinical practice: the GCC allergy and immunology society's HAE case registry puts the estimate at 400 to 600 patients, and the KFSH&RC HAE Registry counts fewer than 200 formally confirmed cases regionwide. Triangulating the three figures does not average them into a single number. It identifies the gap between epidemiology and clinical case-finding as the addressable undiagnosed population.

That gap has a specific, verifiable cause: diagnostic capacity. The entire GCC HAE specialist community numbers just 6 to 10 physicians, concentrated at a handful of centres such as KFSH&RC, and SERPING1 genetic testing plus C1-INH functional assays are available at only a small number of regional laboratories. Abdominal attacks, which account for 50 to 70 percent of all HAE episodes, are frequently misdiagnosed in the GCC as gastroenteritis, appendicitis, or gynaecological conditions before a correct diagnosis is reached. A sizing model built only on the case registry would understate the addressable population by exactly this diagnostic-capacity margin, while a model built only on epidemiology-adjusted prevalence would overstate the near-term reachable population by ignoring the same testing bottleneck. Sensitivity analysis ranks diagnostic capacity as the assumption most likely to move the total, ahead of background prevalence rate itself.

Every AXLRx market sizing exercise triangulates at least two independent methods, epidemiology-based and registry/case-based, before accepting a patient count. For GCC hereditary angioedema, the gap between the two methods is the story: it identifies the diagnostic-capacity constraint as the addressable undiagnosed population, rather than forcing a single averaged number.

GCC hereditary angioedema sources: Al-Hamdi K et al. (Ann Allergy Asthma Immunol 2020; Saudi Med J 2020), the GCC allergy and immunology society HAE case registry, the Saudi Allergy Society clinical meeting 2023, the KFSH&RC HAE Registry 2022, and the SACIA membership directory.