Epidemiology puts US PNH prevalence at 15,000 to 20,000 patients; claims data puts the treated population at roughly 3,500. The 11,500 to 16,500-patient gap between them, not the prevalence rate itself, is what a US sizing model has to explain.
Two independent methods size the US PNH population, and they measure different things. The epidemiology-based method starts from the International PNH Registry and related published literature, estimating total US prevalence at 15,000 to 20,000 patients, median age 35, split across three clinically distinct phenotypes: haemolysis-dominant (roughly 8,000 to 10,000 patients), aplasia-dominant (roughly 4,000 to 5,000), and thrombotic (roughly 2,000 to 3,000), plus an EVH-dominant subset of 800 to 1,200 patients with persistent anaemia despite anti-C5 therapy. The claims-based method counts patients actually on complement-inhibitor therapy: roughly 3,500 patients, split approximately 55% ravulizumab, 25% eculizumab, and 10% iptacopan.
The gap between the two methods, 11,500 to 16,500 patients, is the addressable undiagnosed and undertreated population, and it has specific, sourced causes. Mean diagnostic delay runs 2.4 years from first haemolytic symptom to confirmed diagnosis, driven by misdiagnosis as autoimmune haemolytic anaemia, aplastic anaemia, or MDS; an estimated 15 to 20% of aplastic anaemia patients harbour PNH clones, forming the largest undiagnosed pool. On the new-diagnosis side, 500 to 700 US patients are newly identified each year, but 200 to 400 of those a year go undertreated at non-PNH-centre hospitals lacking FLAER flow cytometry or haematology specialist referral pathways. Our sensitivity analysis ranks diagnostic delay and non-PNH-centre undertreatment ahead of prevalence rate itself as the assumptions most likely to move the addressable total.
US PNH sizing — epidemiology-based prevalence versus claims-based treated population
| Sizing Method | Population Estimate | Source |
|---|---|---|
| Epidemiology-based (total prevalence) | 15,000-20,000 patients across three phenotypes | International PNH Registry; Parker C et al., Blood 2005 |
| Claims-based (treated population) | ~3,500 patients on complement-inhibitor therapy | IQVIA PNH market data; payer formulary data |
| EVH-dominant subset | 800-1,200 patients with persistent anaemia on anti-C5 therapy | APPLY-PNH EVH sub-analysis, NEJM |
| Estimated undiagnosed/undertreated gap | 11,500-16,500 patients | Derived from epidemiology-claims gap |
Sources: Parker C et al. Blood 2005 (International PNH Interest Group); Schrezenmeier H et al. Ann Hematol 2014; Risitano AM et al. NEJM 2023 (APPLY-PNH EVH sub-analysis); IQVIA PNH market data 2024; International PNH Registry.
What this model answers
Every section answers a named commercial question your team is asking, scoped to your asset.
Delivers
- The epidemiology-based and claims-based sizing methodologies
- the 11,500-16,500-patient gap between them
- the specific diagnostic-delay and undertreatment drivers behind it
Delivers
- Sensitivity ranking of every input
- why diagnostic delay (2.4 years average) and non-PNH-centre undertreatment (200-400 patients/year) outrank prevalence rate
- the addressable-population estimate this implies
Delivers
- The 500-700 newly diagnosed patients/year estimate
- the 200-400/year undertreated-at-non-PNH-centre subset
- scenario ranges tied to referral-pathway expansion
Custom model delivered in 72 hours.
Commission This ModelWhat's inside
- Why the gap between epidemiology-based prevalence and the claims-based treated population, not the prevalence rate itself, sizes the US opportunity
- Pressure-tested against the ~3,500-patient treated-population count before the rest of the model is built out
- Total US PNH prevalence of 15,000 to 20,000 patients across three phenotypes
- The 800-1,200-patient EVH-dominant subset defining the oral-switch opportunity
- ~3,500 patients on complement-inhibitor therapy and their agent-share split
- Cross-check against the epidemiology-based estimate
- Where the two methods agree and diverge
- The 2.4-year diagnostic delay and non-PNH-centre undertreatment as the explanation for the gap
- Diagnostic delay and undertreatment ranked above prevalence rate as the binding assumptions
- Scenario ranges tied to referral-pathway and FLAER-testing expansion
- The full triangulated model, re-runnable with your own assumptions
- The open sizing questions your team must close before the number is used in planning
Included with every brief
How AXLRx builds this model
Prepared by MoatRx analysts.
Every AXLRx market sizing model triangulates at least two independent methods, epidemiology-based and claims/registry-based, 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 US sizing sources: International PNH Registry, Parker C et al. (Blood 2005), Schrezenmeier H et al. (Ann Hematol 2014), Risitano AM et al. (NEJM 2023, APPLY-PNH EVH sub-analysis), and IQVIA PNH market data 2024.
- Epidemiology-based prevalence estimate verified against Parker et al. Blood 2005 and the International PNH Registry
- Claims-based treated-population count and agent-share split verified against IQVIA PNH market data 2024
- Diagnostic delay and EVH-dominant subset sizing verified against Schrezenmeier et al. Ann Hematol 2014 and the APPLY-PNH NEJM 2023 sub-analysis
Frequently asked questions
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AXLRx delivers rare disease market sizing models built for forecasting and strategy teams sizing the US PNH opportunity. Custom model in 72 hours.
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Research-verified sizing model in 72 hours with optional analyst readout.