The aHUS patient community asked in its research agenda what are the numbers of aHUS patients.
Global Action has written about this question a lot over the years , trying to make sense of the two different estimates of the prevalence of patients and incidence of new onsets each year.
New onsets treated properly will increase the prevalence of aHUS patient numbers around the world.
Ask the internet about global aHUS incident numbers and this is the kind of responses you get.
“The global incidence of atypical hemolytic uremic syndrome is very low, given that it is a rare disease. While precise rates can vary by region and available healthcare resources, studies estimate the incidence of aHUS to be approximately 1 to 2 cases per million people per year worldwide.
1 to 2 cases per million people globally or 8000 to 16000 new aHUS each year.
Where estimated in individual studies the surviving patients over the years tends to be 10 to 12 times the new annual onsets. Effectively on average past survival would have been 10 to 12 years.
So incredibly there could be 80, 000 to 192000 aHUS patients around the world. That is much bigger potential market for complement inhibitors than is currently sold to treat aHUS patients.
All of course assuming that the 1 to 2 cases per million estimated rate is sound. The evidence for that is from Global Action’s understanding not sound.
Ask the internet what prevalent rate of surviving aHUS patients is and it will say something like “Overall, the prevalence is approximately 2-9 cases per million, with higher detection rates in regions with greater awareness and diagnostic capabilities.”
That is quite a spread of global estimates. At the lower end it is about 16,000 and the higher end 72, 000. At the lower end of the it means that on average aHUS patients life span is two years if incidence rate is 8000 and 1 year if incident number are 16,000.
At the higher end it would be an average life span of 9 years at an incidence of 8000 and 4.5 years at an incidence of 16000.
Something is not adding up where the estimated average global life span after an onset is 1 year to 9 years or 10 to 12 years.
The suspicion falls on the incidence rate. So what influences that? What would the internet say.
Firstly on Genetic Predisposition .aHUS is often associated with genetic mutations that affect the complement system (such as mutations in the CFH, CFI, or MCP genes). The prevalence of these mutations may vary slightly across populations, but no region is known to have a significantly higher risk of aHUS solely due to genetics.
Secondly environmental and health related triggers . While genetic mutations often underlie aHUS, environmental or health events (such as infections, pregnancy, or surgery) can trigger an aHUS episode in predisposed individuals. These triggers are common worldwide, so the onset could theoretically happen anywhere though the mix of triggers may vary
Thirdly awareness and diagnostic capabilities areas with advanced healthcare systems and greater awareness of rare diseases, more cases of aHUS are likely to be identified. In contrast, in regions with limited diagnostic resources, cases may go undiagnosed or be misclassified as other conditions (e.g., TTP or other types of kidney disease). Although in recent years capability’s of clinicians in the developing countries to identify aHUS has grown through education by professional bodies such as the International Society of Nephrologists. It may appear less common in countries with fewer diagnostic capabilities, even though the true incidence could be similar to the more advanced countries.
So the real rate of incidence is more likely to be consistent throughout the world but the prevalence may vary by the level and quality , accessibility and affordability of health care for aHUS patients
What would be the incidence in a country with accurate enough records to produce a reasonably accurate rate of aHUS incidence.
In England where the NHS has an expert aHUS diagnostic service which evaluates all incidents of TMA referred to and with application of consistent criteria determines which are aHUS cases has seen 20 and 30 cases per year for the past ten years or more. England has a population of around 55 million. So its incident rate has been around 0.5 cases per million.
Although not absolutely precise given that incidence is unlikely to vary significantly from country to country around the world it would not be unreasonable to apply 0.5 per million incidents per year which would mean 4000 patients onsetting with aHUS each year.
In 2011 there were around 150 aHUS patients known about in England and over 300 patients have been diagnosed since. Some may have died but at around 450 prevalent patients. On that basis prevalence rate for England would be 17 times the annual incidence. So is likely to be at the higher end of world prevalence rates.
If the data from England is the same in other developed countries, USA for examples would have had around 165 incident aHUS patients and its prevalent aHUS patient population would be around 2800.
On the other hand countries like India with a much greater population with the same incident rate as England would have around 700 new aHUS patients each year but with a lower prevalence rate because of unmet clinical needs would probably be the same prevalence numbers as the USA.
So incident numbers of aHUS globally is pretty much the same each year but the prevalence although variable between countries will grow gradually each year as more affordable access to treatment becomes available with a noticeable step up if countries China and India’s aHUS patients unmet needs are fulfilled.
So there will be higher numbers of aHUS patients in the future because of complement inhibitor treatment access but to get that treatment a correct diagnosis is essential. Otherwise some aHUS patients remain invisible.
Some of the previous Global Action articles on this topic are listed below with links.
Article No. 699
Are there 3000 aHUS patients in the USA
Health care and better estimating lead us to believe there are approaching 3000 aHUS patients in the USA who have survived their encounter with their disease, if not already 3000.…
CONTINUE READINGAre there 3000 aHUS patients in the USA
Iceland and aHUS
Nearly 400,000 people live in Iceland. At normal prevalence levels there should be two aHUS patients. There are at least three in Iceland. They are all in one family. The…
CONTINUE READINGIceland and aHUS
Is incidence of aHUS really “2 per million”?
I know it should not matter so much but whenever I see incidence and prevalence figures for aHUS in articles etc, it often “does my head in”. Quite some confusion…
Epidemiology – aHUS Agenda Topic 15-
aHUS epidemiology is the about how many aHUS patients there are. The numbers onsetting and surviving. It’s “Incidence” and “prevalence”. How many aHUS patients are there in my local area,…
USA aHUS Patients-2000 or more and rising?
Article No. 362 27 July 2020 Ask Google ” how many aHUS patients are there in the USA?” and you will not get an exact answer. Understandable really, as there…
