Hard on the heels of the publication discussed in the previous post, a new publication comparing interventions and outcomes for babies at the same sort of gestational ages from 12 regions in 5 different European countries (if we can still call the UK European!)
You have to do some of your own arithmetic to find out what is going on here, the denominator for all the presented data is the total number of births, which includes stillbirths, and babies not receiving active care. For example, at 22 weeks and less than 500 g, there were 3 babies in the Italian regional cohort (of 34 births) that received respiratory support, which is 9%, but there were only 6 live births in this category, which mean that 50% of live births received such an intervention, in none of the other regions did any such babies (under 500g and 22 weeks gestation) receive respiratory support.
Over 500g there were 4 babies in Italy, and 1 in Portugal that received respiratory support, and no survivors in any of the regions.
I really don’t see the point of reporting survival and the other data among all births, when many were stillborn, but not presenting survival among live births or among those who received active care. It is not surprising for example that the Portuguese region did not provide respiratory support for any of the 22 weekers of less than 500g because they were all stillborn!
The authors suggest that this was to “improve comparability between countries where there are differences in whether a birth is reported as live or not” which implies that they did not have a common definition of a live birth between the regions, and means that the data become much less useful. It is also in contrast to an earlier statement in the methods “the use of the common EPICE recruitment criteria allowed to overcome these differences and provide comparable data across the five countries”.
Here is one figure from the publication:
You can see at 23 weeks gestation that the only survivors are in Italy and the UK. Under 500g there was one baby in the UK that had respiratory support, who died, and 3 in Italy with one survivor. You can calculate therefore that survival at 23 weeks and under 500 grams is actually 25% if you institute active intensive care! Not bad… but that percentage would be almost as meaningless as the number in the table 3 which calculates a survival of 1%, among all the 88 births in that weight and gestation category, live births, still births and babies not receiving respiratory support included.
At 23 weeks and over 500 grams there were no babies receiving intensive care in the French regions, 1 in the Belgian region, 1 in the Portuguese region, 24 in the Italian cohort and 30 in the UK. The only survivors were in Italy and the UK with 7 and 14 survivors respectively.
The conclusion in the abstract of this study ends like this:
Universally poor outcomes for babies at 22 weeks and for those weighing under 500 g suggest little impact of intervention and support the inclusion of birth weight along with gestational age in ethical decision-making guidelines.
Er, No. “Universally poor outcomes for babies at 22 weeks and for those weighing under 500g who did not receive intervention suggests that if you don’t actively treat babies in the periviable period, they all die.”
I do think there is useful and interesting information in this publication, but I think you should take the statistical significance of some of the testa with a grain of salt, the 2 babies treated in the Italian region under 500g at 22 weeks is “significantly” different to the zero treated everywhere else, but does it mean anything?
I think the authors are right that birth weight is as important as gestational age in decision making and should be taken into account when estimating survival, and counselling parents. Birth weight is only known with accuracy after birth, however, and I don’t think that these data give a real justification for using a universal cutoff of 500 grams, chosen arbitrarily for this article. Why not 550 grams? or 454? I think it is unlikely that there is any step-wise sudden improvement in survival between 499 grams and 501 grams, just like gestational age, which doesn’t come in distinct 7 day bundles, and is never known with certainty (except after IVF), we should nuance our counselling, with the real uncertainties in our data and the gradual improvements in survival with increasing hours and days of gestational age and increasing grams of birth weight.