Johnson and Daviss have been stung by my criticism. They have created a website to answer the questions I have raised. However, they can't answer the most important question. Why didn't they compare homebirth in 2000 with hospital birth of low risk women in 2000? I know why. The neonatal mortality rate for low risk white women at term in the year 2000 is only 0.72/1000. So the results from their study of homebirth is 3-4 times HIGHER than the comparable risk group in the hospital in that year. The basic point is that homebirth in 2000 had a higher neonatal death rate than hospital birth of low risk women in 2000, and Johnson and Daviss left that out of the study. Keep that fact in mind as we analyze their response.
How do I know that Johnson and Daviss are attempting to respond to my criticism? Understanding Birth Better.com was created on February 8, 2007. My first post on the topic, Johnson and Daviss study shows death rate more than double the hospital group, was posted on January 12, 2007. I followed up with further analysis, More finely grained results for neonatal mortality in 2000, on January 16, 2007. Johnson and Daviss recognize that my criticism of their study is truly serious and essentially invalidates their conclusions. They are attempting to respond, but as I said above, they do not address the central issue: The left out the only comparison that really matters, the comparison between homebirth in 2000 and low risk hospital birth in 2000.
I would draw your attention to several aspects of their "response".
1. It is written to obfuscate and confuse. This is a classic tactic. They are trying to dazzle their supporters with "scientese" that means nothing.
2. It is heavily padded with irrelevant information. No one asked and no one cares why the study was published in BMJ, yet the bulk of the beginning of the response includes this information.
3. It include the apples-orange "riff" created in conjunction with Henci Goer who also could not respond to my criticism of the study, What led up to Henci Goer's refusal to debate.
4. Johnson & Daviss recognize that their failure to disclose conflicts of interest call the results of the study into question. As I wrote in Research and special interests/the BMJ 2005 study:
Therefore, I was distressed to find that Johnson and Daviss, authors of the 2005 BMJ study that was the largest study of homebirth to date, are NOT independent researchers. In the paper, Johnson describes his professional position as "senior epidemiologist, Surveillance and Risk Assessment Division, Centre for Chronic Disease Prevention and Control, Public Health Agency of Canada", but he neglected to mention that he holds another position: head of the MANA Statistics and Research Committee. In fact, Johnson and Daviss have been passionate homebirth advocates for many years, long before they embarked on the study. Daviss, who is Johnson's wife, is a homebirth midwife. Furthermore, the study was not funded by an academic institution or a government agency. Rather, it was funded by Foundation for the Advancement of Midwifery, a homebirth advocacy group.Let's look at what Johnson & Daviss have to say in their defense:
So using money from a homebirth advocacy group, NARM, a homebirth advocacy group, hired homebirth advocates Johnson and Daviss to produce a study on homebirth. The conclusion appears to be predetermined. When an industry hires known allies to do a study about that industry, the results are going to be favorable.
The study was not commissioned by any national or state midwifery group. However, we are greatly indebted to the North American Registry of Midwives for their role in requiring all CPMs to participate in the data collection as a requirement for renewal of their CPM credential.Clearly, NARM collaborated with Johnson & Daviss to create the study. Midwives were required to participate or their CPM credential would not be renewed. NARM was, at a minimum, an undisclosed partner to Johnson and Daviss.
"In fact, the risk to NARM, should the outcomes reflect negatively on the care by CPMs, was substantial and significant."
Oh, no it wasn't. If the results were negative, the study would not have been submitted for publication. As it is, the authors had to resort to a deceptive and invalid comparison in order to fabricate a positive conclusion. Moreover, the same data has been collected in every year since 2000. Not only has none of it been published, none of it is available to the public. It will only be released to persons who promise to use it for "the benefit of midwifery" and who sign a legal confidentiality requirement that prohibits them from sharing the data with anyone else. This strongly suggests that the existing data shows that homebirth is not as safe as hospital birth.
"Initial and primary funding was obtained from the Benjamin Spencer Fund, a small, private foundation with program interests in the environment, women and families and reproductive rights."
And the remainder of the funding was obtained from The Foundation for the Advancement of Midwifery, as the authors themselves disclosed in the paper.
In other words, all my assertions are correct. Johnson & Daviss are known, longtime public advocates of homebirth. Johnson has been professionally associated with MANA. NARM was intimately involved in the creation of the study and enforced the participation of the midwives. The study was funded by money from a midwifery advocacy group.
In summary, Johnson & Daviss recognize that my criticism of their study is legitimate and serious. They have set up a website to respond. However, they fail to address the key issue. The neonatal death rate at homebirth in 2000 is 3-4 times higher that the neonatal death rate in the hospital for comparable risk women. They don't even mention it. Their study NEVER showed that homebirth was as safe as hospital birth and should not be quoted as such. Indeed, as I have maintained, it shows that homebirth has an excess rate of preventable neonatal death in the range of 1-2/1000, which makes it consistent with other existing homebirth research.
This piece first appeared on Homebirth Debate in June 2007.