Article No. 372
1 September 2020
One thing is certain, no one knows how many aHUS patients there are in the world. Neither how many onset each year, nor how many are surviving. There are no complete records anywhere, no database nor disease registry does that job.
This is not untypical of attempts to find the incidence and prevalence of any health condition. Currently COVID 19 is a good example of that difficulty. In the early stages there was a need to predict how it would impact , how many cases would there be? Ways were needed to estimate likely incidence and prevalence. On such estimates Governments would be expected to take action. It was particularly urgent to know the projected death incidence. But how could these be derived?
It is claimed that the projected incidence of COVID 19 was based on screening the passengers on six flights out of Wuhan, China . Six passengers were found to have COVID 19 out of a total of nearly 700 passengers . The incidence rate derived from that of just under 10,000 per million suggested a major health problem, depending also on how many would be severely damaged or die from complications of the infection.
Greater efforts have probably been made over the years to define aHUS incidence and prevalence rates. But even these efforts are limited ( see Article 369) . They can be used to estimate the number of patients in a given population. Such rates have been around for a long time and were useful to demonstrate that aHUS fell with the definition of a Rare Disease. Knowing that was important to get attention.
Recently aHUS Global Action attempted to re-estimate the number of aHUS patients in the USA ( see Article 362). Traditionally a figure in the six hundreds has been frequently quoted , increasing only by a small number each year as the official population of the US has grown. The traditional prevalence rate estimate was not based on any formal study that has been carried out in the USA.
Neither has it taken account of how many more people in the USA are surviving each year as a result of improved healthcare, not least because of access to the complement inhibitor eculizumab.
Greater awareness of the condition and improved clinical knowledge has also raised identification of the disease when diagnosing the cause of an onset. In the past many aHUS patients would have died or gone into kidney failure without knowing why.
The incidence and prevalence rates of aHUS in the USA should be world leading given the amount spent on treatment and healthcare in the USA.
So when aHUS Global Action arrived at its own estimate of US aHUS patients, it was not too much of a surprise that there are probably more than five times as many as was thought. Over 3000 aHUS patients, although initially we recoiled and settled on a lower figure. But there have been some thoughts that we did not go high enough because our baseline “representative patient cohort“ was too adult and the proportion of children to adults with aHUS was not high enough.
Prevalence of children with aHUS is limited to those patients who are less than 18 years of age. On the other hand for adults incidents occur over a period of 55 years, assuming a normal life expectancy of 73 years. For there to be equal numbers of child and adult aHUS patients the children’s incidence rate has to be three times higher than the adult incident rate. Any rate higher and there would be more children than adults ; any lower and there would be more adults.
So if the children’s prevalence rate is higher there should be relatively more of them than has been calculated in Global Action’s estimates prevalence estimates. Adjusting the Global Action estimates for a higher number of children with aHUS could push the USA aHUS prevalence up to 5000 patients.
So 2000 , 3000, 4000, 5000 estimated patients in the USA. There is a case for any of those numbers. All still make aHUS a very rare disease. All would be a significantly higher patient population than has been assumed using the traditional, but outdated, prevalence rates.
If the USA is at the most favoured end of aHUS diagnosis and treatment outcomes, what could it be like at the other end?
In Developing Countries such as those in Africa , the incidence of aHUS could be just as high. The genetic and environment factors that trigger the disease may differ but the likelihood of onset would be similar, The actual identified incident patient population would be much lower because of incomplete diagnosis.
The treated incidence will be much lower too not just because no access to expensive complement inhibitors but also no universal access to plasma therapy, dialysis and other supportive therapies. The death incidence will be much greater and so the surviving patient population that make up the prevalent population will be much lower.
Prevalence rates for the developing world will probably be lower than they were in the developed world two decades ago. Maybe less than 25 % of the historic developed world rates.
Imagine a world where the Global aHUS Patients vision has been met. One where everywhere aHUS patients get just what is available today in the USA and a US aHUS prevalence is achieved globally. What would global aHUS patient numbers look like then?
The following table provides some “rough“ calculations to illustrate what that might be if an aHUS Global Action estimate of a 3500 US prevalent population (1O.5 per million population) is nearest the mark.
|Population Millions||Incidents of aHUS||Current prevalence||Vision prevalence|
|Rest of the developed world||970||900||10500||10500|
The Global aHUS Patients Vision prevalence would mean that roughly 60,000 more aHUS patients would be alive today.
The question then becomes what could have been done for the aHUS 60k , or their successors.
What ever can be done it certainly will not be down to one thing. Certainly not one treatment nor one Pharma’s solution. It could have costed up to $30 billion per year to have treated them with Alexion’s complement inhibitors. And even then, many Developing Word aHUS patients would not have had the preliminary care and support including dialysis and plasma therapy to survive long enough to get a diagnosis to benefit. The Developing World’s healthcare infrastructure is nothing like what is on offer in the USA and other leading developed countries. The Developing World also has other abundant health and social care challenges and priorities.
Neither international aid nor international charities with their Telethons and fund raising campaigns can help the aHUS 60k. They are not even likely to come within the scope of what these benevolent organisations are set up to do. Charitable foundations which support US aHUS patients in need could not cope with that level of aid.
There are many reasons for an aHUS Awareness Day on September 24th.
Some see it as a day that gives recognition to those who have gone through the experience and the reasons they got through it .
This year it has been about how those who got through and found their own ways to build up their health again. It is important to acknowledge and applaud that.
Whilst at the same time also remembering those who merely had the “wrong genes, in the wrong place, at the wrong time”. The aHUS 60k.
As it is mostly an online event aHUS Awareness Day can be more inclusive with aHUS participants from all around the world.
It is for the aHUS 60k that raising aHUS awareness is done as much as anything.
By letting people know that good can come. The well-being and wellness of those who survive is a testament to that.
We might not have known the aHUS 60k , nor they us, but aHUS still links us none the less.
More about the aHUS awareness day video project HERE.
aHUS Awareness Day 24 September.