Claim: 600 children in Australia suffer from stroke every year

If this is the true number, it seems a lot larger than it should be. I think it's miscalculation. Or has the number been increasing?

This figure is inflated, and why this is important.

These figures are very important because one possible side effect of the Covid mRNA vaccines is cardiovascular problems. I think we would all like to know if the rate of childhood stroke goes up after children have been given the vaccines. There is no doubt that medical experts make mistakes at times, and this appears to be one of those times; one would rather see the mistake humbly corrected than covered up. (The mistake corrected plus a footnote noting the change on the relevant webpage would do).

HOW FIGURES BECOME INFLATED

It is very interesting to see how numbers can become inflated sometimes, through a series of apparently small estimation errors (some might say it’s intentional, but that can’t be proven, so Hanlon’s Razor). It is pretty clear that the number of strokes in children in Australia should be around 3 in 100,000, which is approximately 200 children who suffer from stroke every year in Australia.

What is interesting here is that these figures have gradually become inflated, through a series of cumulative errors, which revolve around the difference between the rate of stroke in children and the rate of stroke in infants.

600 children per year suffer stroke?

The ABC and the Stroke Foundation page on childhood stroke both quoted an estimate of 600 children per year in Australia who suffer from stroke. In fact this was an inaccurate figure, the upper range of an incorrect estimate.

Once we ferret out the original studies this figure actually derives from, we find that it comes from the number of newborns who suffer from stroke, not the total number of children who suffer stroke.

The figure quoted in previous years on the Stroke Foundation page on childhood stroke is also incorrect, 300-500 children, as here the upper estimate is also derived from an estimate of the number of newborns who suffer stroke.

This error becomes possible is because the percentage of newborns who suffer strokes is higher than older children.

Should be “up to” 600. Not “Approximately” 600

According to the Stroke Foundation email:

In that profile (Mark Mackay) also says “About three to 10 children per 100,000 will suffer a stroke.” According to the estimates from the Australian Bureau of Statistics https://www.abs.gov.au/statistics/people/population/national-state-and-territory-population/sep-2021 , in June 2021 there were 5,670,079 people in Australia under the age of 18 (I added up the numbers for ages 0 to 17 inclusive). Going by the rates given by Mark Mackay, that would mean between 170 and 567 strokes in that population. The upper bound in that calculation seems to me the likely source of the estimate of “up to 600”.

On the Stroke Foundation page about children who suffer stroke, by 30 August 2022 the page still says “Stroke can happen at any age. Approximately 600 Australian children have a stroke each year.”

But actually, if according to the Stroke Foundation themselves, 600 is the upper limit of an estimate, it is certainly not the average number of children who suffer from stroke in Australia every year, which is what “approximately” implies to me.

“Approximately 600” is different from “up to 600”, folks.

In their email (see the comments) they also quote this working paper by Simone Mandelstam (I don’t think it is peer reviewed): https://www.researchgate.net/publication/321964954_The_Diagnosis_and_Acute_Management_of_Childhood_Stroke_CLINICAL_GUIDELINE_2017

Simone Mandelstam has an estimate of 1.2 to eight children per 100,000 a year, meaning between 58 and 390 strokes in children, and between 76 and 122 strokes in newborn infants, each year in Australia - the stroke foundation came up with their figure of 300-500 strokes each year by adding these together, which is unfortunately dubious also, as in all the statistics I have seen, newborn infants are actually included in the figure for children.

SIMONE MANDELSTAM’S WORKING PAPER - THE SOURCE OF THE INCORRECT ESTIMATE

The working paper by Simone Mandelstam actually refers to four studies in quoting the figure of 1.2-8 children who suffer from stroke.

Stroke is a major cause of morbidity and mortality in children across the world. In developed countries, the reported incidence of stroke in children over one month of age ranges from 1.2 to eight per 100,000 per year (see references 1-4). For neonates (less than 1 month of age) and preterm babies the incidence of stroke is significantly higher occurring one in every 2500 to 4000 live births (see references 2, 4). In Australia, the actual incidence of childhood stroke remains unknown. In 2016 children accounted for approximately 22% or 4.88 million of Australia’s total population, and 305,337 newborn babies were registered (5). The application of international incidence rates would therefore estimate there to be between 58 and 390 strokes in children, and between 76 and 122 strokes in newborn infants, each year in Australia. Systematic collection of patient data across tertiary paediatric centres is planned following implementation of the Clinical Guidelines to gather epidemiological data on the incidence, causes of, and outcomes following childhood stroke in the Australian population.

I went to the four studies she cites to see what they actually said.

This Denmark based population study finds only a rate of 1.33 plus 0.25 per 100,000 person years, i.e. 1.58 per 100,000 children.

https://pubmed.ncbi.nlm.nih.gov/21114523/

Results: We identified 211 patients with AIS and 40 patients with CSVT corresponding to IRs of 1.33 (95% CI 1.16-1.52) and 0.25 (95% CI 0.19-0.34) per 100,000 person-years, respectively. The IRs peaked in infancy (<1 year) for both AIS and CSVT with an additional peak among adolescents (15-18 years) for CSVT. The IR of AIS increased 3.9% per year (p=0.036), whereas no changes were found for CSVT. In total, 48.2% of the patients received antithrombotic treatment; no major complications were observed. All-cause and thrombosis-related 30-day case fatality ratios were 3.6% and 2.4%, respectively; neurological sequelae were found in 56.2% of patients.

Conclusion: The IR of AIS was highest in infants and had increased with 3.9% annually during the observation period. The IR of CSVT had an additional peak in adolescence and remained unchanged over time.

This study from Northern California finds an incidence of ischemic stroke of 2.4 per 100,000, which could imply 5 per 100,000 strokes in total.

https://pubmed.ncbi.nlm.nih.gov/19762687/

A total of 205 ischemic stroke cases were confirmed, yielding an ischemic stroke incidence of 2.4 per 100,000 person-years.

This study finds a rate of 1.6 per 100,000 per year of arterial ischaemic stroke in children.

Incidentally I could not find Mandelstam’s figure of 1 in 2,500 to 4,000 strokes in live births anywhere.

4.14 arterial ischaemic strokes per 100,000 NEWBORNS

There is a rate in this study, though, of 4.14 newborns per 100,000 of arterial ischaemic stroke, which one could hypothetically double to find the number of strokes in total in newborns.

https://pubmed.ncbi.nlm.nih.gov/24304598/

Findings: We identified 96 cases of arterial ischaemic stroke. The crude incidence of childhood arterial ischaemic stroke was 1·60 per 100 000 per year (95% CI 1·30-1·96). Capture-recapture analysis suggested that case ascertainment was 89% (95% CI 77-97) complete. The incidence of arterial ischaemic stroke was highest in children aged under 1 year (4·14 per 100 000 per year, 95% CI 2·36-6·72). There was no difference in the risk of arterial ischaemic stroke between sexes (crude incidence 1·60 per 100 000 per year [95% CI 1·18-2·12] for boys and 1·61 per 100 000 per year [1·18-2·14] for girls). Asian (relative risk 2·14, 95% CI 1·11-3·85; p=0·017) and black (2·28, 1·00-4·60; p=0·034) children were at higher risk of arterial ischaemic stroke than were white children. 82 (85%) children had focal features (most commonly hemiparesis) at presentation. Seizures were more common in younger children (≤1 year) and headache was more common in older children (>5 years; p<0·0001). At least one risk factor for childhood arterial ischaemic stroke was identified in 80 (83%) cases.

So the upper incidence of 8 per 100,000 children may well come from the figure of the incidence of 4.14 children per 100,000 per year of arterial ischaemic stroke in children under the age of one.

This means the upper figure of 500 from the figure 300-500 quoted in past years on the Stroke Foundation website is also incorrect, because it is mis-ascribing the incidence of stroke in children under the age of one to all children in Australia.

https://pubmed.ncbi.nlm.nih.gov/28254555/

Results: Among 1129 children enrolled with arterial ischemic stroke, stroke incidence was 1.72/100,000/year, (neonates 10.2/100,000 live births).

This is perhaps the source of the figure of 10 children per 100,000, which is again the rate of strokes among newborn children.

My Original article:

Dodgy figures? Dodgy facts? Something is dodgy.

The figures on kids’ strokes in Australia keep inflating - 2-3 per 100,000 is the accepted figure. But since 2020 when it was 300-500 kids in Australia have strokes apparently (a figure that is too high still) it is now 600 kids, according to the stroke foundation website, funded by Pfizer. 

The rate of stroke in children is apparently well documented in numerous population studies: it ranges from 2-3 per 100,000 children per year. It is worth noting that these population studies are old - 1990 to 2000. But nonetheless these figures are still often quoted in studies and on medical websites.

Around 18-20% of Australia’s population of 26,000,000 are children aged 0-14.

This would mean that the number of children who have strokes in Australia should be around 96-140 children per year, if the rate was 2-3 per 100,000.

There are two different types of stroke: Ischemic and Hemhorrhagic. In children it seems the rate of Ischemic stroke is around 60% (in adults it is quite different, Ischemic is about 10% of the total.) (I note this because some of the studies below deal with either Ischemic, or Hemhorrhagic, or both.)

This ABC news item aired on 27 March 2022 says that 600 children per year in Australia suffer from strokes; the link should open up at the exact point at which the reporter says this:

The Stroke Foundation, an Australian organisation that provides information and support for stroke victims, also says that the rate is around 600 children per year in Australia. This may be where the ABC got their figures from.

Interestingly, we can discover using archive.org that this figure on the childhood stroke page has changed. In 2020, it was 300-500 strokes per year.

<the following speculations were answered by the stroke foundation email, in which they outlined their rationale for the figure of 600>

Now perhaps, with better cerebral imaging, the number of strokes being diagnosed has increased. Are more parents taking their kids into the emergency department who have strokes?

But has the rate of childhood strokes being diagnosed really increased 6 times? It seems astonishing. What is going on here?

There is no reference that I can find on the Stroke Foundation page to tell me where they got this figure of 600 children from. Was it a study? The ABS? I can find ABS combined statistics on heart disease stroke and vascular disease and it is zero percent of the population aged 0-14 in 2020.

The ABS gives us statistics of heart disease and stroke, but does not break it down anywhere I can find into separate categories. The rate of childhood vascular diseases in 2020-21 was negligible; 0% in fact, which means effectively less than 0.05% given the precision in the data.

Calculation error?

I wonder if the stroke foundation figure of 600 is a calculation error?

Let’s assume a rate of say 2.3 per 100000 children

2.3/100,000 * 26,000,000 * 18% = 107 children per year

18% is the percentage of children approximately in Australia - if we assume they thought it was 2.3 per 100,000 whole population.

2.3/100,000 * 26,000,000 = 598 children per year

<As it turns out - it was indeed a calculation error, but not the one I thought.>

Questionable

Considering the questionable nature of this figure, one can’t help feeling suspicious that there is more to this. Why did the stroke foundation figure of strokes in children in Australia per year increase from 300-500 children in 2020, to 600 children in 2022? Are there more strokes? And why is it so much larger than the rate the studies show, of 2-3 per 100,000 per year? Has the diagnosis rate increased? Or is something else going on?

<In fact they justify the increase on the basis of a population increase. Sorry, but the population of children in Australia did not almost double since 2020. It did not increase by 20% either. >

I’m sure it doesn’t have anything to do with Pfizer funding the stroke foundation.

<As I said, there is no evidence that Pfizer influenced these estimates at all - they appear to be innocent errors or cumulative miscalculations, apparently. >

FINAL CONCLUSIONS

The ABC and the Stroke Foundation page on childhood stroke both quoted an estimate of 600 children per year in Australia who suffer from stroke. This figure is surely wrong and in fact derives from the percentage of newborn infants who suffer from stroke, not the percentage of children overall who suffer from stroke.

The figure previously quoted on the Stroke Foundation page on childhood stroke is also incorrect, 300-500 children, as here the upper estimate is also derived from an estimate of the percentage of newborns who suffer stroke.

The true figure is surely 100-200 children per year in Australia who suffer strokes. 200 is in fact a pretty high estimate I think.

If it turns out to be higher than that this year then there are some disturbing questions that need to be answered.

Curiously the page the Stroke Foundation references in their email about the expert in childhood stroke, Doctor Mark Mackay, who possibly quite innocently quotes the inflated estimates, which originally derive from Simone Mandelstam’s working paper (and he was part of the working group who came up with this paper according to the email from the stroke foundation), seems to have disappeared.

Luckily it was archived by the Wayback Machine.

References

The working paper by Simone Mandelstam, the source of the original incorrect figures.

https://www.researchgate.net/publication/321964954_The_Diagnosis_and_Acute_Management_of_Childhood_Stroke_CLINICAL_GUIDELINE_2017

The references in Simone Mandelstam’s working paper:

1.58 per 100,000

Tuckuviene R, Christensen AL, Helgestad J, Johnsen SP, Kristensen SR. Paediatric arterial ischaemic stroke and cerebral sinovenous thrombosis in Denmark 1994-2006: a nationwide population-based study. Acta Paediatr. 2011;100(4):543-9.

2.4 per 100,000, which could imply 5 per 100,000 strokes in total.

Agrawal N, Johnston SC, Wu YW, Sidney S, Fullerton HJ. Imaging data reveal a higher pediatric stroke incidence than prior US estimates. Stroke. 2009;40(11):3415-21.

1.6 per 100,000 per year of arterial ischaemic stroke; but 4.14 newborns per 100,000 of arterial ischaemic stroke

Mallick AA, Ganesan V, Kirkham FJ, Fallon P, Hedderly T, McShane T, et al. Childhood arterial ischaemic stroke incidence, presenting features, and risk factors: a prospective population- based study. Lancet Neurol. 2014;13(1):35-43.

1.72/100,000/year, neonates 10.2/100,000

deVeber GA, Kirton A, Booth FA, Yager JY, Wirrell EC, Wood E, et al. Epidemiology and Outcomes of Arterial Ischemic Stroke in Children: The Canadian Pediatric Ischemic Stroke Registry. Pediatr Neurol. 2017;69:58-70.

2.6 to 3.1 cases per 100,000 children per year:

Broderick J, Talbot GT, Prenger E, Leach A, Brott T. Stroke in Children Within a Major Metropolitan Area: The Surprising Importance of Intracerebral Hemorrhage. Journal of Child Neurology. 1993;8(3):250-255. doi:10.1177/088307389300800308

2.3 to 2.59 cases per 100,000 children per year

Risk of stroke in children Ethnic and gender disparities Heather J. Fullerton, Yvonne W. Wu, Shoujun Zhao, S. Claiborne Johnston Neurology Jul 2003, 61 (2) 189-194; DOI: 10.1212/01.WNL.0000078894.79866.95

Ischemic Stroke Rate 1.72 per 100,000 per year, Canada, 1992-2001:

Gabrielle A. deVeber, Adam Kirton, Frances A. Booth, Jerome Y. Yager, Elaine C. Wirrell, Ellen Wood, Michael Shevell, Ann-Marie Surmava, Patricia McCusker, M. Patricia Massicotte, Daune MacGregor, E. Athen MacDonald, Brandon Meaney, Simon Levin, Bernard G. Lemieux, Lawrence Jardine, Peter Humphreys, Michèle David, Anthony K.C. Chan, David J. Buckley, Bruce H. Bjornson,

Epidemiology and Outcomes of Arterial Ischemic Stroke in Children: The Canadian Pediatric Ischemic Stroke Registry, Pediatric Neurology, Volume 69, 2017, Pages 58-70, ISSN 0887-8994, https://doi.org/10.1016/j.pediatrneurol.2017.01.016 (https://www.sciencedirect.com/science/article/pii/S0887899417300759)

Hemorrhagic Stroke 1.4 per 100000 person-years 2008

The Importance of Cerebral Aneurysms in Childhood Hemorrhagic Stroke A Population-Based Study Lori C. Jordan, S. Claiborne Johnston, Yvonne W. Wu, Stephen Sidney and Heather J. Fullerton Originally published 20 Nov 2008https://doi.org/10.1161/STROKEAHA.108.518761Stroke. 2009;40:400–405

Rates of Ischemic vs Hemorrhagic 2009

Stroke in children under 16 years of age. Clinical and etiological difference with adults M. Giroud,M. Lemesle,G. Madinier,E. Manceau,G. V. Osseby,R. Dumas First published: 29 January 2009 https://doi.org/10.1111/j.1600-0404.1997.tb00306.x

Technological improvement leads to higher diagnosis rates

Tali Jonas Kimchi, Ronit Agid, Seon-Kyu Lee, Karel G. Ter Brugge, Arterial Ischemic Stroke in Children, Neuroimaging Clinics of North America, Volume 17, Issue 2, 2007, Pages 175-187, ISSN 1052-5149, https://doi.org/10.1016/j.nic.2007.02.007. (https://www.sciencedirect.com/science/article/pii/S1052514907000147)

Archived links

https://web.archive.org/web/20200715233925/https://strokefoundation.org.au/About-Stroke/Learn/Childhood-stroke

Note that the background here is white suddenly and mysteriously on the archive.org page when I access it; which hides the text in the foreground; the text can still be selected viz.

Australian Bureau of Statistics

https://www.abs.gov.au/statistics/health/health-conditions-and-risks/health-conditions-prevalence/latest-release

Doctor Mark Mackay

This page seems to have disappeared:

https://www.mcri.edu.au/brilliantminds/Dr-Mark-Mackay

Luckily it was archived on the Wayback Machine, so you can check it out here:

https://web.archive.org/web/20220328073355/https://www.mcri.edu.au/brilliantminds/Dr-Mark-Mackay

The Email from Stroke Foundation

This is the email:

Thank you for … your question about childhood stroke figures. I have passed your question onto --- our Stroke Content Coordinator. Here is his response.

One of our main clinical experts Mark Mackay from the Royal Children’s Hospital, is also on the Stroke Foundation Clinical Council. According to this profile of him from the Murdoch Children’s Research Institute, one of his research interests is “establishing studies to measure the true incidence of childhood stroke”. He is probably the best-informed in this area, but he is still trying to find the correct answer.

In that profile he also says “About three to 10 children per 100,000 will suffer a stroke.” According to the estimates from the Australian Bureau of Statistics, in June 2021 there were 5,670,079 people in Australia under the age of 18 (I added up the numbers for ages 0 to 17 inclusive). Going by the rates given by Mark Mackay, that would mean between 170 and 567 strokes in that population. The upper bound in that calculation seems to me the likely source of the estimate of “up to 600”.

Some more detail is given in the 2017 Guideline for the diagnosis and acute management of childhood stroke, of which Mark Mackay was also the chair. The introduction says:

“In developed countries, the reported incidence of stroke in children over one month of age ranges from 1.2 to eight per 100,000 per year (1-4). For neonates (less than 1 month of age) and preterm babies the incidence of stroke is significantly higher occurring one in every 2500 to 4000 live births (2, 4). In Australia, the actual incidence of childhood stroke remains unknown. In 2016 children accounted for approximately 22% or 4.88 million of Australia’s total population, and 305,337 newborn babies were registered (5). The application of international incidence rates would therefore estimate there to be between 58 and 390 strokes in children, and between 76 and 122 strokes in newborn infants, each year in Australia. Systematic collection of patient data across tertiary paediatric centres is planned following implementation of the Clinical Guidelines to gather epidemiological data on the incidence, causes of, and outcomes following childhood stroke in the Australian population.”

Adding up the numbers for children and newborns gives a maximum of 512 strokes, which given that the population was slightly lower then is roughly consistent with the broader estimate above, but also the older figure of 300-500 strokes.

It’s important to note though that, as with many stroke statistics, these are estimates based on previous epidemiological studies. The quote above states that they’re planning to do systematic data collection to get the true numbers, but as far as I know that data doesn’t exist yet. So when the figure goes up that is more likely due to population increases, together with using a slightly different range of estimates.

I hope this is helpful,

CHANGE LOG

16 August - early morning. Tidied up the conclusions a little and fixed ‘heart’ foundation to ‘stroke’ foundation; and added the Pfizer funding info.

30 August - early morning. Edited the article to reflect the new information from the email in the comments section.

My post on a recent article written to the BMJ on the broken peer review process might be interesting to you too:

Claim: The peer review process is broken.

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