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Does the Hospital “Admission Strip” Conducted on Women in Labor Work as Hoped?

October 3rd, 2013 by avatar

The 20 minute electronic fetal monitoring strip is a “right of passage” for any woman being admitted to the hospital in labor.  But is this automatic 20 minute strip evidence based?  Regular Science & Sensibility contributor Henci Goer takes a look at a recent Cochrane systematic review and lets us know what the research says.  Do you discuss this with your students?  Do you share about this practice  in your classes and with your patients and students?  What do you tell them? Will it change after reading Henci’s review below? – Sharon Muza, Science & Sensibility Community Manager

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Some weeks ago, I did a Science and Sensibility post summarizing the latest version of the Cochrane systematic review of continuous electronic fetal monitoring (EFM)—AKA cardiotocography (CTG)—in labor versus intermittent listening. A couple of commenters on that post asked if I would tackle the “admission strip,” the common practice of doing EFM for 20 minutes or so at hospital admission in labor to see whether ongoing continuous monitoring is warranted.

I was in luck because the Cochrane Library has a recent systematic review of randomized controlled trials of this practice versus intermittent listening in women at low risk for fetal hypoxia (Devane 2012). The rationale for the admission strip, as the reviewers explain, is that pregnancy risk factors don’t predict all babies who will experience morbidity or mortality in labor. The admission strip is an attempt to identify women free of risk factors whose babies nevertheless might benefit from closer monitoring. Let’s see whether the admission strip succeeds at identifying those babies and improving their outcomes.

As to whether the admission strip identifies babies believed to be in need of closer surveillance, the answer is “yes.” Pooled analysis (meta-analysis) of the trials found that 15 more women per 100 allocated to the admission strip group went on to have continuous EFM (3 trials, 10,753 women), and 3 more babies per 100 underwent fetal blood sampling (3 trials, 10,757 babies).

Furthermore, women almost certainly underwent more cesareans as well (4 trials, 11,338 women). All four trials reported more cesareans in the admission strip group. The pooled increased risk of 20% just missed achieving statistical significance, but this is probably because cesarean rates were so low, only 3 to 4% in by far the biggest trial, which contributed 8056 participants. Because of the lack of heterogeneity among trials, the reviewers think the difference is likely to be real. If it is, then using an admission strip in low-risk women results in 1 additional cesarean for every 136 women monitored continuously (number needed to harm). I would add that not separating out first-time mothers, who are at greater risk for cesarean delivery, probably masked a bigger effect in this subgroup. How big an effect might this be?  Let’s assume a 9% cesarean rate in low-risk first-time mothers, that being the rate found  in first-time mothers still eligible for home birth at labor onset in the Birthplace in England study (2011). At this cesarean rate, a 20% increase over baseline would calculate to 1 additional cesarean for every 55 first-time mothers monitored continuously.

The crucial question, though, is whether increased monitoring and surgical deliveries produced better perinatal outcomes. To that, the answer is “no.” Combined fetal and neonatal death rates in infants free of congenital anomalies were identical at 1 per 1000 in both groups (4 trials, 11,339 babies). The reviewers acknowledge that their meta-analysis of over 11,000 babies is still “underpowered,” i.e., too small to detect a difference in outcomes. However, they continue, the event is so rare in low-risk women that no trial or meta-analysis would likely be big enough to do so. Additionally, no differences were found for cases of hypoxic ischemic encephalopathy (1 trial, 2367 babies), admissions to neonatal intensive care (4 trials, 11,331 babies), neonatal seizure (1 trial, 8056 babies), evidence of multi-organ compromise within the first 24 hours (1 trial, 8056 babies), or even 5-minute Apgar scores less than 7 (4 trials, 11,324 babies).

The reviewers therefore conclude:

We found no evidence of benefit for the use of the admission CTG for low-risk women on admission in labour. Furthermore, the probability is that admission CTG increases the caesarean section rate by approximately 20%. . . . The findings of this review support recommendations that the admission CTG not be used for women who are low risk on admission in labour. Women should be informed that admission CTG is likely associated with an increase in the incidence of caesarean section without evidence of benefit (Devane 2012, p. 2). [Emphasis mine.]

Conclusion

According to the best evidence, the admission strip isn’t just ineffective, it’s harmful, and its use should be abandoned

References

Birthplace in England Collaborative Group. (2011). Perinatal and maternal outcomes by planned place of birth for healthy women with low risk pregnancies: the Birthplace in England national prospective cohort study. BMJ, 343, d7400.  http://www.ncbi.nlm.nih.gov/pubmed/22117057?dopt=Citation

Devane, D., Lalor, J. G., Daly, S., McGuire, W., & Smith, V. (2012). Cardiotocography versus intermittent auscultation of fetal heart on admission to labour ward for assessment of fetal wellbeing. Cochrane Database Syst Rev, 2, CD005122. doi: 10.1002/14651858.CD005122.pub4 http://www.ncbi.nlm.nih.gov/pubmed/22336808

Childbirth Education, Do No Harm, Evidence Based Medicine, Fetal Monitoring, Guest Posts, Maternity Care, Medical Interventions, Metaanalyses, New Research, Research, Uncategorized , , , , , , , ,

The Wax Home Birth Meta-Analysis: An Outsider’s Critique

October 23rd, 2012 by avatar

Today’s post is a fascinating interview that took place between Rebecca Dekker, PhD, RN, APRN of Evidence Based Birth and Kyoung Suk Lee, PhD, MPH, RN, APRN. Rebecca asked Dr. Lee to provide a review of the Wax Home Birth Meta-Analysis, as an “unbiased outsider”, but highly skilled researcher.  Dr. Lee’s comments and critique are fascinating and provided me with many further thoughts.  Please enjoy Rebecca’s interview and share your comments. – SM

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Shortly after starting my website, www.evidencebasedbirth.com, I had several people ask me if I could write an article about the research evidence on home birth. However, I was hesitant to do so for several reasons. Mainly, I was worried that I could not look at the evidence in an objective manner. My husband and I had recently chosen a home birth for our second child. I was worried that it would be difficult to objectively examine the research evidence on home birth, given my personal experience. The blogosphere is full of people who are strongly pro-home birth or anti-home birth, and their evaluations of the evidence are usually written through the lens of their own biases. I didn’t want to add to the plethora of biased articles already out there.

Then I had a sudden burst of inspiration. What if I asked one of my colleagues—who has no biases about childbirth—to review the home birth literature for me? In particular, I wanted to find someone who could review the Wax home birth meta-analysis (Wax, Lucas et al. 2010) and give me a fair assessment of its scientific value.

I chose the Wax meta-analysis for this review because in 2011, the American Congress of Obstetricians and Gynecologists emphasized the results of the Wax study in its official statement on home birth. Their statement said: “Women inquiring about planned home birth should be informed of its risks and benefits based on recent evidence. Specifically, they should be informed that although the absolute risk may be low, planned home birth is associated with a twofold to threefold increased risk of neonatal death when compared with planned hospital birth.”(ACOG, 2011)

Dr. Kyoung Suk Lee, PhD, MPH, RN, APRN

It did not take me long to figure out who I would ask to review the Wax study. Dr. Kyoung Suk Lee is considered by her colleagues to be a rising star in the field of cardiovascular research. She recently graduated with a PhD in Nursing, and she just accepted a job at a research university. People who work with Dr. Lee say that she is extremely intelligent, hard-working, and a future leader in her field. Dr. Lee’s expertise has been recognized with research awards from the Heart Failure Society of America, the Society for Heart-Brain Medicine, and the Cleveland Clinic Heart-Brain Institute, among others. She has published her work in nursing and cardiology journals. Furthermore, I knew that Dr. Lee did not have any biases about childbirth, home birth, or hospital birth. I asked Dr. Lee if she would be willing to review the Wax meta-analysis for me, and she kindly agreed.

What follows is my interview of her about the study and its results (RD in bold, KSL unbolded).

Do you have any biases or conflicts of interest related to home or hospital birth?

I do not have any biases related to home or hospital birth.

Could you summarize the methods and results of the Wax study?

The purpose of this meta-analysis was to compare maternal and neonatal outcomes between planned home-and hospital-births.

Using an electronic database search and bibliography search, the authors retrieved 237 articles and included 12 articles in their meta-analyses. Of 12 articles included, 3 were conducted after 2000 while 9 were conducted before 2000. Of 12 articles, 2 were conducted in the US (one was a retrospective design) while 10 were conducted outside US.

Women in the planned home birth group had better maternal outcomes than women in the planned hospital group. They had fewer interventions such as epidurals and episiotomies, and lower morbidity (infection, 3rd or 4th degree lacerations, hemorrhages, and retained placenta). There were no differences in cord prolapse between the two groups.

For neonatal outcomes, babies born to women in the planned home birth group were less likely to experience prematurity and low birth weight. However, babies born to women in the planned home birth group were more likely to experience neonatal death compared to women in hospital birth.

What is the difference between neonatal and perinatal mortality? What does this have to do with the results?

Based on the definitions given by the authors, neonatal mortality was defined as “death of live born child within 28 days of birth.” This is a subset of an overall outcome– perinatal mortality, which was defined as “stillbirth (of at least 20 weeks or 500g) or death of live born child within 28 days of birth.”

According to the authors, there were no differences in perinatal death (the overall outcome) between planned home birth and hospital birth groups. However, homebirth was associated with 2 times higher risk for neonatal death (the subset of deaths occurring 28 days after birth) in all infants and 3 times higher risk for neonatal death in infants who did not have any congenital birth defects.

Interestingly, if you look at page 243.e3, the authors did a sensitivity analysis. In this analysis, they excluded the studies that had home births that were not attended by certified midwives or certified nurse midwives. In this analysis, they found that there were no differences in neonatal deaths between the home birth and hospital birth groups. This means that in the studies in which midwives with certification of some kind attended home births, the outcomes were the same except there was no increase in the neonatal death rate. In my opinion, we have to pay attention to results of sensitivity analyses because this allows us to see the results based on studies which were definitely known to be eligible or clearly described their methods and outcomes.

What is your opinion on the scientific rigor of this meta-analysis?

One thing that was strange to me is the odds ratios (ORs) in the tables. For example, in table 2, under morbidity, the percentages of infection between home births and hospital births were 0.7 vs. 2.6 (its OR was 0.27) while percentages of perineal laceration were 42.7 vs. 37.1 (its OR was 0.66). To a researcher, these numbers don’t make sense.

Many of the studies included were older (half of the studies were conducted more than 20 years ago) so results may not reflect the current practice at home births or hospital births.

The authors did not provide detailed information on how they evaluated the quality of studies included, although they cited a paper describing the method of study evaluation. This makes it difficult if not impossible to determine whether the studies they included were of good or poor quality.

The authors mentioned that women with high risks would prefer hospital births so that it would expect that home births have better outcomes than hospital births in some maternal and neonatal outcomes. If this was a concern, I wonder why the authors didn’t just focus on only the studies that used matching methods, in order to minimize confounding factors.

What is the difference between relative risk and absolute risk, and how does that apply to women who want to have a home birth?

Absolute risk is the probability of something occurring. They may be expressed as percentages or ratios. For example, neonatal mortality rate in the United States is 2.01 per 1,000 live births. This is .201 percent (2.01/1000 = .201/100).

http://www.flickr.com/photos/mikeporcenaluk/3789756395/

Relative risk is a comparison between different risk levels, such as the neonatal mortality rate of home birth compared to the neonatal mortality rate of hospital birth. The researchers found that there was a higher relative risk in neonatal mortality at home births compared to hospital births, but the overall absolute risk for both was small.

How can women know whether the Wax study results would be applicable to their own individual situation?

Meta analysis is one way to generalize findings from different studies. However, women and clinicians should interpret these results cautiously because the studies included were very different from one another and some of the studies included may not have been of good quality. Also, it would be important to note that the overall neonatal death rate that they report reflects home births that were attended by midwives as well as those that may not have had any kind of certified midwife present.

Because this study seems to have some flaws, the conclusion is tentative. I do not know if this article has any implications for pregnant women.

What do you think is the value of asking someone with no conflicts of interest to evaluate controversial research? Does Dr. Lee’s even-handed critique make you view the results of this study any differently? How do you feel about Dr Lee’s conclusion that the study’s results are tentative, and that the Wax study might not have any implications for pregnant women? Please share your thoughts and comments with other readers.

References

(2011). “ACOG Committee Opinion No. 476: Planned home birth.” Obstetrics and gynecology 117(2 Pt 1): 425-428.

Wax, J. R., F. L. Lucas, et al. (2010). “Maternal and newborn outcomes in planned home birth vs planned hospital births: a metaanalysis.” Am J Obstet Gynecol 203(3): 243 e241-248.

About Rebecca Dekker

Rebecca Dekker, PhD, RN, APRN, is an Assistant Professor of Nursing at a research-intensive university and author of www.evidencebasedbirth.com. Rebecca’s vision is to promote evidence-based birth practices among consumers and clinicians worldwide. She publishes summaries of birth evidence using a Question and Answer style.

Babies, Childbirth Education, Evidence Based Medicine, Guest Posts, Home Birth, Metaanalyses, Midwifery, New Research, NICU, Research , , , , , , , , , , , ,

Jumping to conclusions: Popular media spins an abstract into headlines.

February 23rd, 2012 by avatar

A new study has been making the rounds of the popular news sites.  The abstract – 65: Neonatal outcomes associated with intended place of birth: birth centers and home birth compared to hospitals  The abstract of the study is published in AJOG It was presented at the Society for Maternal-Fetal Medicine 32nd Annual Meeting.

It is strange that this abstract is getting so much attention. With only an abstract available it is impossible to judge the study’s merits. We look forward to the publication of the study. At this point we have to reserve judgment for later.  We simply don’t have the data available to determine the strength or validity of the study.  That said, it is amazing that the findings presented in the abstract are getting so much attention.

Here are some of the many articles, with varying perspectives, discussing it: 

I found this article to be neutral verging on steering families toward hospital birth:

 “Babies born at home were more than twice as likely to have an Apgar score of under 7 as children born in a hospital or at a birthing center, and also had double the chances of having a seizure….

The overall number of kids who had seizures was low — less than 1 percent at any location.

Prior research has shown that babies with lower Apgar scores are more likely to have complications after birth, such as needing breathing assistance, going to the ICU, having seizures or having developmental issues, Cheng said.”

Study Weighs Pros, Cons of Home or Hospital Birth: More seizures, lower Apgar scores found in home or hospital birth  

 

This article has a positive spin for homebirth:

 “But when a certified midwife was present, it seems babies born at home may fare as well as those born in hospitals, said study researcher Dr. Yvonne Cheng, an obstetrician and gynecologist at the University of California, San Francisco.

“It’s not just about where you deliver, but perhaps who you deliver with,” Cheng said.

Home births are known to be associated with fewer obstetric interventions — that is, women in labor at home receive fewer epidurals and less pain medication.

Women must weigh the benefits of home births against the risks to make an informed decision about where to give birth, Cheng said.”

Midwives make homebirth safer for babies  

 

 This article seems to treat the study in a neutral manner:

 “Women who have home births or plan to deliver at home have lower rates of cesarean delivery; however, their babies are more likely to have neonatal seizures and lower Apgar scores if a certified midwife is not in attendance, according to research presented here at the Society for Maternal-Fetal Medicine 32nd Annual Meeting.”

Home Births Associated With More Seizures, Lower Apgar Scores

 

This one uses bad data to back a claim:

“…recent evidence suggests that while the absolute risk of planned home births is low, such births carry a neonatal death rate at least twice as high as that of planned hospital births. Neonatal death occurred less than once in 1,000 hospital births, compared with two in 1,000 home births, said an American Journal of Obstetrics & Gynecology meta-analysis published in September 2010.”

Home births rise despite higher neonatal mortality rate: Although the vast majority of deliveries occur in hospitals, more women who want a less institutional experience are opting to give birth at home.

This AMA article is citing the Wax et al study.  Science and Sensibility has discussed the vast array of errors and misinformation in the Wax study on four separate occasions:

Others have cited Wax et al, although not explicitly such as this one: Homebirths up Dramatically, but are they safe?

There were numerous letters written to AJOG with regards to the flaws in the study, as well.  So, to have the Wax et al study brought up again is inappropriate and poor science.  It feels to me like a scare tactic or propaganda.

Given that we don’t have all the information, I question the journalistic integrity with which the articles above are written.  It’s always a good headline – about the dangers of home birth.  It’ll get links clicked, newspapers sold and running commentary on social media sites.  However, without proper analysis of the data things are potentially misrepresented.  Once we gain access to the full study, Science and Sensibility will be able to respond appropriately.

Some questions we hope to answer:

  • What data were used? How strong is the data set?
  • Many home births are not reported as such, so data will be lacking.  How is this accounted for?
  • Does the legal status of a homebirth midwife impact outcomes?  Especially because the author states that CNMs have better outcomes than do CPMs or DEMs. We are not aware of research that supports this.
  • Is it considered homebirth if the mother was transferred from home to hospital mid-labor if her intention was to have a home birth?

For more on recent perspectives on homebirth please visit the Homebirth Consensus Summit.

Let’s get the discussion going here.  What are your thoughts on homebirth?

Evidence Based Medicine, Guest Posts, Home Birth, Metaanalyses, Midwifery, News about Pregnancy, Research , , , , , , , , , , , , , , ,

When Scientific Methods Fail: New Criticisms Over the Wax et al Homebirth vs. Hospital Birth Study

April 4th, 2011 by avatar

Just when one might think the controversy over the Wax et al planned homebirth vs. planned hospital birth study might be dying down, it is instead heating up again.

The American Journal of Gynecology—in which the study was originally published in September, 2010—released its April 2011 issue last Friday, full of Letters to the Editor criticizing the study.  Written by social science, epidemiology, bioethics and public health doctoral university researchers and midwives, it almost seemed as if the journal was preparing to retract the Wax article by these inclusions.  But really, they were providing the platform for the study authors to respond to the critical letters, as suggested in an excerpt from one of those responses:

“Although our findings may be unpopular in certain quarters, they result from appropriate rigorous scientific methods that have undergone appropriate peer review.”

(More on the “scientific methods” later.)

In the concluding Editor’s comment, we are told an (anonymous) independent panel of maternal fetal medicine experts convened to review the data in the Wax study—a move to theoretically decide whether or not the journal should retract the article.  The panel’s recommendations, following this analysis of the Wax et al data, were that AJOG should publish online, a full summary of the graphs for each outcome included in the study and that no retraction of the article is warranted.  (They did admit to finding ‘minor’ discrepancies in the data—but none that seemed to warrant rescinding the article altogether.)

I will say, I have to give AJOG a little credit here:  they didn’t have to print those letters.  I can only imagine how many letters in a month a large journal like that receives.  The managing and chief editors certainly could have kept all those letters to themselves, never to print a single one.  Perhaps their PR department convinced them that doing so would have created a larger fire storm than the one (still) brewing.

Coming on the heels of articles in Nature and the Lancet, which seriously called into question the conclusions of the Wax study, there has certainly been a lot of pressure on AJOG to address its decision to publish the article at all.

Medscape is also on board the debate—having already re-published the Nature article and now making available a rebuttal article from a group of researchers—including the authors of the British Columbia and Netherlands homebirth studies the Wax article incorrectly attributed and irresponsibly excluded, respectively.  This latest article, entitled Planned Home vs. Hospital Birth: A Meta-Analysis Gone Wrong, by Carl Michal, PhD, et al, was also published last Friday.

An excerpt from the Michal paper encapsulates the problem with the Wax meta-analysis:

The statistical analysis upon which this conclusion was based was deeply flawed, containing many numerical errors, improper inclusion and exclusion of studies, mischaracterization of cited works, and logical impossibilities. In addition, the software tool used for nearly two thirds of the meta-analysis calculations contains serious errors that can dramatically underestimate confidence intervals (CIs), and this resulted in at least 1 spuriously statistically significant result. Despite the publication of statements and commentaries querying the reliability of the findings, this faulty study now forms the evidentiary basis for an American College of Obstetricians and Gynecologists Committee Opinion, meaning that its results are being presented to expectant parents as the state-of-the-art in home birth safety research.

Critical analysis of the Wax study by Michal et al includes the following:
°data included in the study suggests a higher neonatal death rate (for both home and hospital births) compared to perinatal death rates.  This, of course, is not possible as neonatal deaths ought to be included in the perinatal death numbers—therefore the data here are paradoxical in nature.

°multiple numerical errors including inconsistencies in data provided in both original and supplemental source papers; incompatibilities between data from cited sources and that which is represented in the Wax study

°inconsistencies in the authors’ definitions of perinatal and neonatal mortality

°miscalculations of some odds ratios (OR) and confidence intervals (CI)—sometimes to the tune of drastic underreporting of the CI—resulting in inaccurate statistically significant positive or negative results

°inappropriate data inclusion criteria (such as that for perineal tears, in which the Wax study only included data on first and second degree tears, rather than all perineal lacerations)

°the meta-analysis spreadsheet used to calculate 13 out of the 21 outcomes contained a computational error—making all data computed with that spreadsheet incorrect

°inclusion of reference works that, themselves, have been highly criticized for statistical inaccuracies (such as the Pang et al study that included unplanned home births when it had set out to only assess planned homebirths)

°misappropriated causation:

…the discussion of causes of neonatal mortality focuses on findings from studies that were not included in the meta-analysis, including studies that mix high-risk with low-risk cases. Of the studies that are included in the meta-analysis, none associates rates of intervention with rates of neonatal mortality.

AJOG, in an attempt to rule on the debate of whether or not the data presented in the Wax study are even valid, may have just shot itself in the foot.  Since when did ‘we published an inaccurate study, and we stand by those inaccuracies’ become acceptable?

 

(see appropriate references attached to above-linked articles)

Posted by:  Kimmelin Hull, PA, LCCE

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