Remember in the COVID years of 2020 and 2021 the media was plastered with COVID patient numbers. They were ubiquitous and much talked about.
How many people had been tested and had the disease? How many had died? How many survived?
All of which explained the epidemiology of COVID throughout the world. The incidence and survival rates, of COVID in every country and globally.
They were reported at enormous cost as part of the need to influence the general population to change behaviours like accepting lock downs, social distancing and wearing masks.
Or worse to get nationalistic political points from inter country comparisons.
Were they accurate? They were big numbers collected at enormous cost but it is unlikely they will have been entirely accurate.
They were the best available.
But that is the same for all diseases, full records are not kept , collated or reported.
Even for a rare disease like aHUS which ,relative to COVID, would be like counting fingers on one hand.
It fair to say that understanding of aHUS patient numbers is poor. And relies on estimates.
The basis for these estimate are often dubious.
The “science” on which the surviving patient numbers figure of 2 per million ,which is how these prevalence rates are expressed, and which is, even after over 25 year, still cited would not pass review today.
It was the first and best available at the time.
It was based on research separating HUS patients from those who were not i.e. aHUS patients, dependent on whether the patients in one of the handful of USA and Canadian hospitals participating in the research, had diarrhoea symptoms or not. No e coli tests nor other blood tests. Just diarrhoeal symptoms.
As previously mentioned It is still cited today, even in the USA where patients have had access to a complement inhibitor for the effective treatment for more than 14 years and that surely would have added greatly to the surviving patients numbers.
So it’s understandable that the 45 participants might not be much aware of aHUS patient numbers.
For the RDD 25 aHUS video they were asked whether they knew the number of aHUS patients in their Town or City, Province or State , and Country.
If not they were asked to estimate a number.
There was no right answer as far as estimates are concerned they are just approximations.
Those approximation would depend on the definition of aHUS, age of patients included and the extent of access to the best quality of treatment in the country.
So focussing on the country number responses first. The participants were from 12 countries.
No one knew the total number of patients in their country. There were a handful of responses about number of other patients they knew of in their country, but as could be expected those were a small fraction of likely country patient numbers.
Twenty participants said they had no idea how many there could be.
Thirteen estimated lower numbers and two had remarkably higher estimates. 18,000 for the USA was the highest. Maybe one day the prevalence will be nearly 60 aHUS patients per million and it would still be a rare disease!
Only 7 out of the 45 had estimates which were in the ballpark of the likely estimated country patient numbers. Five of them were patient advocates in their country.
The other two Taylor and Siddhiksha had the nearest patient estimates for USA and Canada respectively.
Siddhiksha nearest estimation to Canada’ s likely aHUS patient numbers
aHUS alliance’s country estimates are below categorised by the prevalence rates 2 , 4 , 6 and 7 per million based on a primary aHUS definition, all ages, and length of time and scope of access to complement inhibitors in those countries:
7 per million
| Country | Estimated aHUS patients |
| USA | 2380 |
| UK | 478 |
| France | 477 |
| Australia | 186 |
| Portugal | 74 |
6 per million
| Canada | 248 |
4 per million
| Brazil | 852 |
| Mexico | 520 |
2 per million
| China | 2838 |
| South Africa | 128 |
| Iraq | 91 |
| Hong Kong | 15 |
These 12 countries together have an estimated prevalent aHUS patient population of 8287.
The general population of the 12 countries is around 2.437 billion.
If the overall prevalence rate in these countries of around 3.3 per million was representative of the rest of the world too, the estimated total surviving global aHUS patient population is about 27,000.
At the other end of scale there is an issue which is not untypical for those with a rare disease.
Twenty nine of the participates say they did not know, and estimated that there were 0/1 patients in their town/city and nineteen of them were right to say so. Based on likely estimates for their locality they were likely to be the only ones with aHUS.
A rare disease can be isolating for many.
The highest likely aHUS patient population in a city was 58 in New York City where Camilla lives.
Many countries would not have as many potential aHUS patients as New York City has.
Least understood are patients numbers in states and provinces. Only five participants estimated numbers which could be described as within “reasonable” distance of the likely estimates for their states/provinces.
The 45 participants have helped raise awareness of aHUS numbers in towns/cities, states/provinces and countries.
In doing so they may have contributed to a ” global aHUS prevalence rate” of 3.3 patients per million. This figure is probably more valid than the using the 2 per million figure.
If used 3.3 per million it would estimate the global aHUS patient numbers at around 27,000 higher than the 16000 estimated using the 2 per million rate.
The 45 also provided a novel insight into the total numbers impacted in the families of the 45 patients and biggest familial impacts are described. This will be reported in the second part of the RDD25 aHUS video insights which can be read HERE.
Article No. 714
