Maternal Mortality, Death Certificates, and Churnalism
Celebrating great work analyzing data
I filled out my first death certificate in 1991. By 1993, I was the final arbiter of the certificates I completed. In 1997, I began to face the bewildering task of filling out death certificates for my outpatients. These were people I had not seen for weeks or months, who had died at home, for whom I had to come up with a cause of death.
I had never been trained to fill out a death certificate and often felt I was doing a rotten job of it. Even with the excellent guidance that exists (See this CDC page, a version of which I have referenced innumerable times), the cause of death that I enter on a death certificates is, sometimes, at best, an educated guess.
The consequences of this are not lost on me. I have been called by family members to discuss a loved one’s cause of death. The callers did not know why their relatives had died and wanted to learn “the facts.” Some of these people have been disappointed when I explain that “presumed pulmonary embolism” due to or as a consequence of “metastatic prostate cancer” was a guess based on what I had been told about the final minutes or hours of a person's life.
Furthermore, when I read articles, I am suspicious of any mortality outcome besides “overall mortality.” The difference between cardiovascular mortality and mortality related to an infectious disease or cancer might be definite or might be a barely considered decision made by a sleep-deprived 26-year-old cross-covering a colleague.
In addition to my conflicted relationship with the death certificate, anyone following Sensible Medicine’s churnalism coverage knows that I hold many of our health journalists in low esteem.1 It should thus not be a surprise that I couldn’t help but click wildly when I saw this on X:
Huge congratulations to Saloni Dattani on her award and her outstanding work.2 The award recognized Dr. Dattani’s article The rise in reported maternal mortality rates in the US is largely due to a change in measurement. Her work shows, fairly convincingly, that the rise in U.S. maternal mortality, which we have heard so much about, can be mostly explained (at least between 2003 and 2017) by a change in the way mortality data were collected. Here is the graph of the maternal mortality data from four countries, which appears to show a rise in death rates in the US.
To my read, and you should definitely read the article yourself, the big story is that the low maternal mortality rates we achieved between 1980 and 2002 were thanks to undercounting. The rise in the aughts and teens occurred as we gradually introduced a more accurate system. That a change in reporting had led to the apparent increase in mortality would have been obvious if the change had happened across the country at one time, but the change happened gradually as states changed their death certificates. The mortality rates thus appeared to be slowly rising.
This explains the rise in maternal mortality during this period. It also raises questions about comparisons across countries. Dr. Dattani’s article references the variability in reporting across different nations and ways in which the WHO tries to account for these differences in data collection.
Even as a total skeptic, I did not question reports I read about rising maternal mortality in the US. I should have. This probably reflects the fact that I am not only a skeptic but also a bit of a pessimist. It did not surprise me that mortality rates were rising; why would I question this? Reading this work reminds me, once again, that taking data at face value is not advisable. It also reminds me that our journalists often do not dive deep enough into the studies on which they report.
The lesson here is neither novel nor profound. When you hear a report or read an abstract, put aside your priors at first and look at the data as a frequentist. Consider, could these results represent type I error or type II error? Could this difference detected not actually exist, or have we missed a difference that does exist? Why might this have happened? Is there a problem with the data itself or with the sample size? Then, put on your Bayesian hat, look at the data in light of what you already know and expect.
Seems to me there are really three stories here. One is about death certificates, and it’s a cautionary tale and an interesting one that I haven’t often contemplated. The second is about churnalism. But my assumption, reading the headlines, was that the *rise* in maternal mortality had not, in fact, occurred. Instead, reading your piece and skimming Datani’s, I see that the *lower* rates for three decades starting around 1980 were the illusory ones, and the current numbers — reflecting the nationwide use of the pregnancy checkboxes on the death certificates — are more reliable. Now that is a very different narrative, with its own disturbing eclat. “Our rates are not rising after all” implies “nothing to see here, move along.” On the contrary! It sounds as if your tendency to pessimism is more warranted than ever, because the actual takeaway appears to be, “US maternal mortality has not in fact been as low as we thought for over 40 years now. To understand the current numbers, we should not be looking for recent changes in maternal circumstances or health-care policy, but rather re-thinking our entire approach for the past half-century.” Talk about a story.
There have been a number of studies showing that death certifications on cause of death are completely unreliable. The most common cause of death is probably old age and the failures of one or more organ systems that go with it. But "heart attack" and ASCVD are cited as the leading causes of death in the US. These default diagnoses are used by doctors to avoid the bureaucratic problems that ensue if one fails to provide an acceptable cause on the death certificate.
I cited a personal experience in a book I wrote about cholesterol and heart disease. One of my senior partners was called to a patient's home in order to pronounce him dead. The patient was lying in bed and was quite obviously dead. My partner slipped his stethoscope beneath the covers and listened for any sounds of respiration or heartbeat. Finding none, he affirmed the diagnosis and returned to the office to await the arrival of the death certificate from the funeral home for his signature. Since the patient was elderly and had a history of heart disease, he was prepared to certify it as a cardiac related death. It was an unpleasant surprise when the mortician called and asked Did you know that this man was shot in the chest?
A classic illustration of the inaccuracy of DC diagnoses. Also a pretty good illustration of the value of at least a cursory physical examination.