CAM usage and vaccination status

ResearchBlogging.orgI’ve often discussed how potentially misleading anecdotal evidence and experience can be. Indeed, I’ve managed to get into quite a few–shall we say?–heated discussions with a certain woo-friendly pediatrician, who, so confident in his own clinical judgment, just can’t accept that his own personal clinical observations could be wrong or even horribly mislead him. Sadly, I’ve never managed to persuade him just how easy it is for us humans to be deceived or even to deceive ourselves.

However, just because anecdotal evidence can deceive us does not mean that it is worthless. Contrary to the straw man argument that woo-meisters like to level against skeptics, we do not claim that anecdotal evidence is “worthless.” Rather, anecdotal evidence is the weakest form of evidence. In science, it is always only a starting point, never an end, at least not if stronger forms of evidence can be generated?

So why am I beginning with this rambling introduction, other than that’s the way Orac usually rolls? The reason is that it’s always been my anecdotal experience that people who tend to pursue “complementary and alternative medicine” (i.e., CAM) tend also to be anti-vaccine. True, there has been evidence that, for example, chiropractors tend to be hostile to vaccination, and that only a many naturopaths are highly skeptical of pediatric vaccination. This sort of anecdotal evidence and relatively small studies led to some curiosity over whether it was really true that CAM is associated with lower rates of vaccination, which is why researchers from the School of Public Health at the University of Washington and the Office of Health Services and Public Health Outcomes Research, University of Missouri decided to take a look at the question. In the process, they just published the largest series thus far to look at the relationship between pediatric vaccination and CAM usage1.

The results are, alas, not surprising.

The authors first start out laying out the background, pointing out the evidence for vaccination hesitancy among chiropractors but that there were conflicting studies. They also mention that only a minority of naturopaths support full pediatric vaccination. In order to try to clarify the issue, they undertook a study of a large sample of non-Medicaid pediatric enrollees in two large insurance companies in Washington State. What was unique about this sample is that these insurance companies pay for CAM because state law mandates it. (Geez, it’s worse than I thought if Washington state mandates insurance coverage of provider-based CAMtherapy.) They then looked for correlations between CAM usage and vaccination. In another twist, they also looked for correlations between CAM usage and vaccine-preventable diseases. Specifically, they looked at five predictors of vaccination outcomes (naturopathic physician, chiropractor, acupuncturist, massage therapist, or conventional care provider) and whether other members of the enrollee’s family used CAM. They then used logistic regression models, correcting for a variety of potential confounders, in order to look for correlations in the 11,144 children studied, using the healthcare effectiveness data and information set (HEDIS) to determine vaccination adherence.

Two tables say it all. First, CAM usage and vaccination status (click for a larger version of the table):


In other words, children using CAM who saw a chiropractor were between 25% and over 40% less likely to have had the four major vaccines studied, against the MMR, chickenpox, diptheria/tetanus, or H. influenzae type B. It was even worse for children who had been under the care of naturopaths. These children were over 75% less likely to have been vaccinated. But that’s not all. Take a look at this next table:


To boil it down, there is an association between being cared for by a naturopath and a higher likelihood of acquisition of vaccine-preventable disease, as well as an association between family members undergoing any CAM care and vaccine-preventable disease. The authors boil it down:

To our knowledge, this is the largest study to date of CAM provider use and immunization rates among young children enrolled in private insurance plans.We found that,among non- Medicaid pediatric enrollees in two Washington State insurance companies, those who received care from naturopathic physicians or chiropractors during the years of their first or second birthdays were significantly less likely to havemet the HEDIS schedule for vaccination against measles/mumps/ rubella, chickenpox, or H. influenzae type B than were their counterparts. Additionally, children who received care from naturopathic physicians were significantly less likely to have received timely protection against diphtheria/tetanus. Diagnosis with vaccine-preventable diseases among children through age 17 years was rare. However, pediatric use of naturopathy was associated with significantlymore diagnoses, and chickenpox was the diagnosis most frequently made.

This study did have some limitations, the most glaring of which is that it relied on insurance company claims instead of definite diagnoses. This could conceivably underestimate the vaccination rate if children received any vaccinations outside of the system. However, it’s unlikely that it would underestimate vaccination rates enough to account for a four-fold difference between children seeing conventional practitioners and naturopaths or even the nearly two-fold decreased vaccination rates among patients of chiropractors. Another problem is that this is a rather select population. It includes insured children not on Medicaid in a very woo-friendly state, with relatively low vaccine uptake rates. Indeed, it should also be noted that Washington is the home to one of the biggest naturopathic schools there is, and it has a high proportion of naturopaths, along with an obnoxious “every category of
” law, the aforementioned law that requires insurance companies to pay for CAM. More importantly, this study cannot show causality. As the authors state:

Lower vaccination rates among pediatric CAM users may reflect either a tendency for parents who prefer natural approaches to health and who are already vaccine-hesitant to seek out CAM professionals, or a pattern of direct influence by CAM providers on parents’ attitudes. Some researchers have suggested that vaccine-hesitant parents may prefer CAM practitioners, in part, because they are less likely to introduce pro-vaccination pressure [32]. Washington State, where our study took place, has demonstrated strong acceptance of chiropractic and naturopathy into mainstream medical care [44]. Although pediatric vaccination rates in the state have increased dramatically in recent years, Washington currently lags behind 40 other states in childhood vaccination [45]. Our data were not sufficient for evaluating whether these two factors are related.

And it’s true. It’s probably a combination of factors: parents who are already suspicious of vaccines being of the type who prefer “natural” cures and distrust scientific medicine plus chiropractors and naturopaths either not encouraging vaccination or even actively opposing it. In other words, parents with anti-vaccine views tend to prefer quacks, and quacks tend to oppose vaccination. Not that chiropractors are necessarily quacks. The ones who stick to physical therapy-like interventions can be as useful as, well, physical therapists. It’s the ones with delusions of grandeur, who think that chiropractic can treat allergies, asthma, and all sorts of other conditions unrelated to the musculoskeletal system. Either way, though, chiropractors do tend to be either indifferent or hostile to vaccination. Naturopaths, however, are worse. Vaccination, in fact, tends to go against the very tenets of naturopathy, which tends to be based not so much on the germ theory but rather an updated and tarted up variant of primitive vitalism. Aside from some sensible recommendations about diet and exercise, naturopathy is mostly quackery.

Unfortunately, the authors stumble in that they fall into the all too frequent trap of being excessively tolerant and deferential to quackery:

Our findings suggest that interventions with CAM practitioners and parents may be needed to increase support for pediatric vaccination. Future research aimed at developing successful interventions must include in-depth studies of parents and CAM providers to assist in understanding more precisely the important provider-related deterrents to vaccination. Intervention protocols will need to be responsive to the extent to which CAM providers are directly instrumental in reducing immunization or merely incidental to the patient population served.

This is in essence an admission of defeat. Basically, the authors are saying that, rather than reforming the system to prevent, for example, naturopaths from performing primary care functions that would allow them to hinder the vaccination of children, the best we can do is to try to educate those who are, for the most part, uneducable when it comes to vaccines, given that what they are taught in their training mostly denies the need for or efficacy of vaccination. On the other hand, if society as a whole devalues science-based medicine to the point where it has decided that naturopathy is a valid specialty, even though, as PalMD has shown, naturopaths are clueless when it comes to primary care, then we have no one to blame but ourselves for this sorry state of affairs. It is a testament to the sad state of medicine in this country, with its increasing acceptance of so-called “complementary and alternative medicine,” that it would even be necessary to propose such an education campaign in order to protect children from vaccine-preventable disease.

Such are the wages of quackademic medicine.


Downey, L., Tyree, P., Huebner, C., & Lafferty, W. (2009). Pediatric Vaccination and Vaccine-Preventable Disease Acquisition: Associations with Care by Complementary and Alternative Medicine Providers Maternal and Child Health Journal DOI: 10.1007/s10995-009-0519-5