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Apgar Score of Zero at Five Minutes

post #1 of 129
Thread Starter 

Hey everyone! I was just wondering, has anyone seen this new study? http://www.ajog.org/article/S0002-9378(13)00641-8/abstract

 

It was just published this week. What researchers found is that "Home births and births in free-standing birth centers attended by midwives had a significantly higher risk of a 5-minute Apgar score of zero (p<.0001) than hospital births attended by physicians or midwives. Home births and births in free-standing birth centers attended by midwives had a significantly higher risk of neonatal seizures or serious neurologic dysfunction (p<.0001) than hospital births attended by physicians or midwives."

 

That p<.0001 means that the chance is greater by 1000%, or 10X greater. So they found home birth and birth in free-standing birth centers had a 10X greater chance of 5-minute Apgar scores of zero (no signs of life) and 10X greater chance of neonatal seizures or serious neurologic dysfunction.

 

They concluded with "The increased risk of 5-minute Apgar score of zero and seizures or serious neurologic dysfunction of out-of-hospital births should be disclosed by obstetric practitioners to women who express an interest in out-of-hospital birth."

 

I was just wondering if anyone's seen this, and what your thoughts are on it?

post #2 of 129
I don't think that's what a p-value means....
post #3 of 129
Quote:
Originally Posted by krst234 View Post

I don't think that's what a p-value means....

Yeah, that's not what a p-value is. http://www.americannursetoday.com/article.aspx?id=6214&fid=6182
post #4 of 129
Thread Starter 

Oh, sorry, you're right about that.

 

But the study does still show there's an a 10X increase the chance of a zero Apgar score, as seen by Table 2 in the study. In that table, it shows that 0.16% of infants attended by hospital MDs and 0.09% of infants attended by hospital midwives had Apgar scores of 0 at five minutes, while 0.55% of infants attended by birth center midwives and 1.63% of infants attended by homebirth midwives had Apgar scores of 0 at five minutes.

 

 

 

 

So, to summarize that: compared to hospital MDs, the chance for an Apgar score of 0 was 3X higher with birth center midwives. Compared to hospital midwives, the chance for an Apgar score of 0 was 6X higher with birth center midwives. Compared to hospital MDs, the chance for an Apgar score of 0 was 10X higher with home birth midwives. Compared to hospital midwives, the chance for an Apgar score of 0 was 18X higher with home birth midwives.

 

I don't know how much higher the chance of neonatal seizures or serious neurologic dysfunction are, other than there is a significant increase.

 

Sorry for the mistake again, these are the corrected numbers. 


Edited by Pillowy - 6/28/13 at 6:27pm
post #5 of 129

Of the OOH midwives, does anyone know what the breakdown was of CNMs vs CPM vs, LMs vs DEMs?
 

post #6 of 129
Quote:
Originally Posted by Pillowy View Post

Oh, sorry, you're right about that.

But the study does still show there's an a 10X increase the chance of a zero Apgar score, as seen by Table 2 in the study. In that table, it shows that 0.16% of infants attended by hospital MDs and 0.09% of infants attended by hospital midwives had Apgar scores of 0 at five minutes, while 0.55% of infants attended by birth center midwives and 1.63% of infants attended by homebirth midwives had Apgar scores of 0 at five minutes. 

Yes, it does show that there is a 10-fold increase in Apgars of 0 in the homebirth midwives vs. the hospital MD groups, but your percentages are way off. The numbers given in the table are per ONE THOUSAND, not one hundred, so the percentages are off by a decimal point. Hospital MDs have a rate of .016% and homebirth midwives a rate of .163%. Both of those absolute risks are very low. I would also ask how homebirth midwife was defined in the study and why more attention was not drawn to the fact that hospital midwives had HALF the rate of babies with Apgars of 0 when compared to hospital MDs wink1.gif That seems like an interesting statistic given that they are dealing with equivalent available technology and personnel. There *are* circumstances where being in a hospital is beneficial for a baby, and a baby who needs extensive resuscitation (intubation, epinepherine) is one of them. A homebirth midwife is not going to be able to do those things and would need to transport for that type of situation.
post #7 of 129
Thread Starter 

You're right again. :) My percentages are off by a decimal point, but the ratios remain the same. So, like you said, the chance is still 10X greater (hospital MDs vs. home birth midwives). 

 

I also thought it was interesting that the hospital midwives had half the 0 Apgar scores as MDs. I'm guessing that is partly due to the fact that the midwives are going to be dealing almost exclusively with the low-risk groups, while MDs cover all births - including all high-risk ones.

 

I have to say I am disturbed that home birth midwives have 18X the chance of having an Apgar score of 0 at five minutes than hospital midwives have. As you say, there are circumstances that are going to require equipment that isn't available at home. Transfer is obviously what you want to do when the baby is born with an Apgar of 0, but when 5 minutes have already gone by and the Apgar is still 0 and the paramedics haven't arrived yet...I don't like the thought. And the question also is, were there warning signs during labor (that should have led to a transfer) that the midwife missed? 18X higher is just crazy. 

post #8 of 129
Thread Starter 
Quote:
Originally Posted by mothercat View Post

Of the OOH midwives, does anyone know what the breakdown was of CNMs vs CPM vs, LMs vs DEMs?
 

 

I don't think they distinguished between the groups, but I might be wrong. Does anyone else know?

post #9 of 129

The most interesting part for me was the large difference between the hospital deliveries with a midwife and the home deliveries with a midwife.  Both groups of midwives should be caring for the same population of women--low risk.  So it seems more reasonable to compare the homebirth midwife deliveries with the hospital midwife ones than it does to compare the homebirth midwife deliveries with hospital OB ones.  What do you think the big difference between place of delivery with a midwife can be attributed to? 

post #10 of 129
Well rnra, the main thing that comes to mind for me in answer to your question is that almost always, the only midwives practicing in hospitals would be cnm's or cm's. that is not necessarily the case for home birth midwives
post #11 of 129
"I have to say I am disturbed that home birth midwives have 18X the chance of having an Apgar score of 0"

I don't believe this study established this - it determined the groups were ***statistically different***...but not by 18-fold. That's a different statistical test. be careful making assumptions about data, or of others' interpretation of data.

That said, I can think of a few reasons why the risk of zero apgars in an OOH setting could be statisically different than in a hospital setting. Does this number address outcomes? A hospital NICU team could get a non-zero APGAR for quite a few neonates that will not survive.
post #12 of 129
Oh, and it's no secret that high-risk deliveries (twins, breech, VBAC) are being attended OOH by midwives so I would imagine that would account for some of the poorer outcomes, too.
post #13 of 129
Quote:
Originally Posted by krst234 View Post

Oh, and it's no secret that high-risk deliveries (twins, breech, VBAC) are being attended OOH by midwives so I would imagine that would account for some of the poorer outcomes, too.

 

I would also think that hospital midwives (CNMs and CMs) would have a higher volume of clients. Even if the percentage of babies that start with a zero Apgar were the same, the number of babies they treat would be higher. This would mean they have more experience and probably better skills.

Hospital based providers are also required to complete one or more of the national resuscitation classes like NNR, ALSO, PALS every year or every 2 years to maintain their hospital privileges.

 

For licensed OOH midwives NNR may also be a requirement for their license and needs to be completed every 2-3 years. Same for CPMs, every 2 years. However, if the midwife is unlicensed and not a CPM at minimum, then what incentive does she have for remaining current in resuscitation?

 

That was the reason for my question about the breakdown of the different categories of midwives, not just hospital based vs. OOH.

post #14 of 129
Thread Starter 
Quote:
Originally Posted by krst234 View Post

"I have to say I am disturbed that home birth midwives have 18X the chance of having an Apgar score of 0"

I don't believe this study established this - it determined the groups were ***statistically different***...but not by 18-fold. 

 

Actually, it does show that. If you look back at Table 2, it showed that for hospital midwives, 95 infants out of 1,115,794 had an Apgar score of zero at five minutes. That's 0.009%. Home birth midwives had 98 infants out of 60,296 with an Apgar score of zero at five minutes. That's 0.163%. 0.163 divided by 0.009 is 18.1111. Thus, for this (very large sample size) group of health care providers, the home birth midwives had 18X more Apgar scores of zero at five minutes.

 

Furthermore, the researchers said that "It is essential to note that these significantly increased risks of adverse outcomes from the setting of home and from the setting of free-standing birth centers reported here may be serious underestimations of clinical complications." So these numbers may even be an underestimate.

post #15 of 129
The authors assert 'significant difference' not 18x or 10x or whatever. These are different inferences. They tested the first, not the latter.

Again, beware of believing everything you read on the internet.
post #16 of 129
Thread Starter 
Quote:
Originally Posted by krst234 View Post

The authors assert 'significant difference' not 18x or 10x or whatever. These are different inferences. They tested the first, not the latter.

Again, beware of believing everything you read on the internet.

 

Yes, they assert "significant difference." This means the difference between the two groups is statistically significant. I understand that. The 18X and the 10X come from the data, and I just showed you how.

 

And "Beware of believing everything you read on the internet"? This is a published, peer-reviewed study. 

post #17 of 129
Quote:
That was the reason for my question about the breakdown of the different categories of midwives, not just hospital based vs. OOH.

 

I don't get the impression that the AJOG cares to differentiate between types of midwives, because that would interfere with their objective of discounting all OOH birth options. I'd be interested, too, in knowing how these outcomes vary between types of midwives.

 

 

Quote:
This is a published, peer-reviewed study.

 

Yes. And it doesn't appear that the journal article states that there is an 18-fold difference in zero APGARS, only that there is a difference.

 

If we could read tables and make inferences based on numbers alone, calculations like p-values would be completely unnecessary in determining statistical significance.

I believe the found 'statistically different' values - I don't believe the study demonstrated any magnitude of difference in values. I've only read the abstract. Nothing in the abstract leads me to believe they performed this analysis. It looks like something gleaned by looking at tables..... or by reading some blogger's interpretation of the data.

post #18 of 129
Thread Starter 
Quote:
Originally Posted by krst234 View Post

Yes. And it doesn't appear that the journal article states that there is an 18-fold difference in zero APGARS, only that there is a difference.

 

If we could read tables and make inferences based on numbers alone, calculations like p-values would be completely unnecessary in determining statistical significance.

I believe the found 'statistically different' values - I don't believe the study demonstrated any magnitude of difference in values. I've only read the abstract. Nothing in the abstract leads me to believe they performed this analysis. It looks like something gleaned by looking at tables..... or by reading some blogger's interpretation of the data.

 

The study did demonstrate magnitude of differences in the values. It's not "my interpretation of the data." It's right there in the table, in the study, in column 2. If you look at column 2, you'll see at the top that it says RR (95% CI). RR stands for Relative Risk, which is the topic of this discussion (the different chances the infant will have an Apgar score of zero at five minutes). To be more technical, it's the "ratio of the probability occurring." So, in this study, it's specifically addressing the chance that a zero Apgar score at five minutes will occur, compared between the different professionals.  

 

CI stands for Confidence Interval. Confidence intervals consist of a range of values that act as strong estimates that a number will fall between. It's easiest to explain this with the actual numbers, so please look at the table again. First of all, it says that Hospital MDs serve as the reference group. Check. So that RR will be 1, and the other RRs will be compared to that. Then look at homebirth midwives. That RR is 10.55. That means that compared to hospital MDs, the chance that homebirth midwives will have an Apgar of 0 is 10.55. The confidence interval is 8.62-12.93 and the confidence level is 95%, which means the researchers are 95% confident that the number is between 8.62 to 12.93. So home birth midwives almost certainly have 8.62X to 12.93X as many zero Apgar scores as doctors.

 

Again, this is not just "my interpretation of the data." It's the researcher's interpretation of the data. It's already in the study, right there in column 2.

 

 

Quote:
Originally Posted by krst234 View Post

And it doesn't appear that the journal article states that there is an 18-fold difference in zero APGARS, only that there is a difference.

 

The study uses the Hospital MDs as a reference group, and shows that Homebirth Midwives have a 10.55x greater chance of having Apgar scores of zero than them. 

 

As rnra pointed out, a better comparison would probably be between Hospital Midwives and Homebirth Midwives. Using the same basic calculations that the researchers did (which yielded the 10.55 ratio between hospital mds and homebirth midwives, and which I already demonstrated how to do in a previous answer), you get that Homebirth Midwives have a 18x greater chance of having Apgar scores of zero than Hospital Midwives.

 

One more time - the study does demonstrate the magnitude of differences between the groups. That's what column 2 is. The researchers did it, and they provided the confidence intervals and confidence level. They used Hospital MDs as the reference group. Using Hospital Midwives as the reference group, the ratio is even higher.

post #19 of 129
Thread Starter 
Quote:
Originally Posted by krst234 View Post

 I've only read the abstract. Nothing in the abstract leads me to believe they performed this analysis.

 

And no, it's not in the abstract. That's why it's important to read the whole paper. You don't get all the information from the abstract.

post #20 of 129
Thread Starter 
Quote:
Originally Posted by mothercat View Post

 

I would also think that hospital midwives (CNMs and CMs) would have a higher volume of clients. Even if the percentage of babies that start with a zero Apgar were the same, the number of babies they treat would be higher. This would mean they have more experience and probably better skills.

Hospital based providers are also required to complete one or more of the national resuscitation classes like NNR, ALSO, PALS every year or every 2 years to maintain their hospital privileges.

 

For licensed OOH midwives NNR may also be a requirement for their license and needs to be completed every 2-3 years. Same for CPMs, every 2 years. However, if the midwife is unlicensed and not a CPM at minimum, then what incentive does she have for remaining current in resuscitation?

 

That was the reason for my question about the breakdown of the different categories of midwives, not just hospital based vs. OOH.

 

Yeah, I really wish they had broken down the different certification levels of the midwives. I would love to see the percentages for CNMs, CPMS, DEMS, etc.

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