UK PNH Market Sizing Model

Two counts of the UK PNH population already exist inside AXLRx's own research, and neither was built to be reconciled against the other. The registry-based count comes from the Leeds National PNH Service, which operates the UK's single national registry and a 30-year natural-history dataset: it tracks roughly 600 patients currently on complement-inhibitor therapy, plus a further 100 to 150 patients with small PNH clones who are monitored without treatment. Around 30% of the treated cohort has concurrent aplastic anaemia features requiring dual haematology management. The second count, drawn from AXLRx's own PNH UK Launch Readiness research, puts the total UK PNH population closer to 1,500 patients, with roughly 1,000 on complement-inhibitor therapy, including an EVH-dominant subgroup of 200 to 250 patients that can rise to 400 to 500 under a broader residual-anaemia definition. Triangulating the two means treating the Leeds registry figure as the steady-state, annually reported treated count, and the Launch Readiness estimate as a broader definitional range not yet reconciled against it.

That reconciliation gap sits alongside a second, structurally distinct UK finding: NICE has not applied a single QALY threshold to PNH therapies. Ravulizumab and iptacopan have each cleared NICE appraisal, but sibling AXLRx research disagrees on which route governed ravulizumab: the standard Technology Appraisal process (TA698, 19 May 2021, £20,000 to £30,000 per QALY) is cited in three separate AXLRx briefs, while the Highly Specialised Technology route (HST15, 2022, £100,000 to £300,000 per QALY) is cited in the AXLRx Pricing Strategy Model. Which threshold actually governs matters for sizing because it determines how a commercial team should read the roughly 15 NHS Highly Specialised Services centres, anchored by five named institutions in Leeds, London, Oxford, Cambridge, and Glasgow, that together manage over 90% of the country's PNH caseload through fewer than 25 specialist consultants. Our sensitivity analysis ranks this appraisal-route ambiguity, not prevalence itself, as the assumption most likely to move a UK sizing total.

Every AXLRx market sizing model triangulates at least two independent methods before accepting a patient count. This is explicitly a sizing model (static patient count), distinct from a Patient Flow or forecasting model (dynamic revenue/uptake).

PNH UK sizing sources: Leeds National PNH Service annual registry reporting, the British Committee for Standards in Haematology (BCSH) PNH guidelines (2020), the NHS England Highly Specialised Services specification for PNH (2022), and AXLRx's own PNH UK Launch Readiness research.