By Lynne Slim, RDH, BSDH, MSDH
According to Wikipedia, the popular quote, “There are three kinds of lies: lies, damned lies, and statistics” may have been originated by a British prime minister. Statistics, in particular, confuse dental hygienists, especially because they can be misconstrued and twisted to meet someone’s particular point of view. A spin doctor refers to a person who ensures that others interpret data from a particular point of view.
More columns from Lynne Slim
Different strokes are used in periodontal instrumentation
Perio/Cardio Link Debunked
Efficacy of antioxidants
Many of us, including me, are frankly tired of hearing the “spin” surrounding some of the oral-systemic links. The perio/cardio (ASVD) link is one that I am very passionate about, especially because I recently spent many months reviewing the science with a co-author periodontal researcher on the strength of the evidence surrounding this particular link.1 We hear all kinds of statements from speakers, writers, companies, and health-care professionals about this link and some of the spin sounds like this:
Bacteria can travel throughout the body and cause serious health problems. Keeping your gums healthy can reduce your risk of a heart attack. Tell your patients that untreated periodontal disease can put them at risk for future heart problems or that periodontal inflammation can contribute to chronic systemic inflammation and atherosclerosis-induced diseases.
Are these statements true, or is it just spin-doctoring to promote a compelling but non-causal link?
I opened my September 2012 issue of RDH magazine to find that one of my columns (“Perio/Cardio Link Debunked,” July 2012 issue) was the topic of a letter to the editor by Dr. Michael Rethman.
In his letter, Dr. Rethman claims that “truth exists independent of science.”
The truth in patient decision-making should not be based on personal perspective or spin in dental media. It should be based on rigorous analysis of sound science. For example, millions of women were duped by their physicians who relied on marketing messages by pharmaceutical companies in recommending hormone replacement therapy (HRT) as preventive medicine. (HRT) was derived from conjugated equine estrogens that actually increased (instead of preventing) the risk of invasive breast cancer, stroke, cardiovascular disease, heart attack, pulmonary embolism, and blood clots. They took HRT under the presumption that they would be protected against cardiovascular disease. Drug companies that marketed HRT knew of potential problems and covered up the truth.
The use of hormone therapy changed abruptly when the results from the Women’s Health Initiative randomized controlled trials were reported. Researchers found that HRT actually posed the above mentioned health risks, especially when given to postmenopausal women. As the concerns about HRT mounted, doctors (including my own internist) became less likely to prescribe it.
In human terms, of the 8,506 women who were treated with estrogen plus progestin, there were 40 more coronary events, 40 more strokes, 80 more episodes of venous thromboembolism, and 40 more invasive breast cancers than the 8,102 women who were assigned to a placebo drug.2 Hundreds of thousands of women worldwide were harmed by HRT.2
I just finished reading a great article that described the actions of some health-care providers in preventive medicine. The author noted instances where providers are sometimes “aggressively assertive” with symptomless individuals and tell them what they must do to remain healthy. He goes on to say that we must justify the aggressive assertive approach based on the highest level of randomized evidence that our preventive maneuver will, in fact, do more good than harm.2 He states:
“Without evidence from positive randomized trials (and, better still, systematic reviews of randomized trials) we cannot justify soliciting the healthy to accept any personal health intervention.There are simply too many examples of disastrous inadequacy of lesser evidence for individual interventions among the healthy: supplemental oxygen for premies (causing retrolental fibroplasia), healthy babies sleeping face down (causing SIDS), thymic irradiation of healthy children, and the list goes on.”2
AGGRESSIVE ASSERTIVENESS IN DENTISTRY
Here’s an example (in dentistry) of how aggressive assertiveness with oral/systemic links can be detrimental, especially when the media gets wind of it. Offenbacher was quoted as saying that the bacteria in the mouth of a woman with gum disease can trigger an increase in a chemical compound called prostaglandin and other harmful inflammatory molecules.3 These chemicals, according to Offenbacher, can induce early labor and impair fetal growth.3 The prevention of low birth weight babies through scaling and root planing that many speakers/writers promised — and the millions of dollars spent in clinical trials — all came to naught. In the end, researchers discovered that nonsurgical periodontal therapy did not result in fewer low birth weight babies.
The periodontal community promised to save the world by reducing low birth weight incidence. Have any apologies from the periodontal community been issued for those false promises about premature births and low birth weight babies?
Dr. Rethman’s letter to RDH indicates that dental hygienists would be wise to “ignore” the American Heart Association’s (AHA) statement regarding the link between periodontal disease and heart disease. For the record, let’s take a look at the AHA statement, the systematic review of the literature that led to the statement, and discuss its significance. (See Table 1 to read the AHA statement.)
It is clear in reading the AHA scientific statement that there is inconclusive evidence that the successful treatment of periodontitis will prevent the onset of cardiovascular disease or slow its progression. The same conclusion was made in the systematic review that found there was an independent association between periodontitis and cardiovascular disease.4
Intervention studies or trials (higher level studies) studying the effect of nonsurgical and/or surgical periodontal therapy upon definitive outcome measures for cardiovascular conditions — admissions to hospitals or cardiovascular-related deaths — are not available.1 Existing research trials have included only what are called surrogate outcome measures for cardiovascular diseases — biomarkers of systemic inflammation such as C-reactive protein (CRP) and/or endothelial dysfunction, referred to as “intima-media thickness.”
Therefore, evidence for a causal association between periodontal and cardiovascular disease is incomplete. It has been recommended that intervention studies examining the effect of periodontal therapy on cardiovascular conditions should include large sample sizes to allow for statistical analyses of adequate statistical power, as well as long-term followup periods to record definitive cardiovascular endpoints. The only intervention study completed to date is an underpowered multi-site pilot study that found periodontal treatment over a period of up to three years did not reduce cardiovascular events when the treatment group was compared to the group with “community care.”5
Dr. Rethman believes it’s reasonable for dental hygienists to alert patients about science that suggests that better oral health may decrease the incidence or severity of ASVD-related events such as strokes and heart attacks. In other words, he believes in causality even though there is no evidence that periodontal treatment prevents ASVD or modifies its outcomes.
The U.S. Preventive Services Task Force (USPSTF) makes recommendations about preventive care services for patients and bases its recommendations on a systematic review of the evidence of the benefits and harms and an assessment of the net benefit of the service. The USPSTF found that there wasn’t enough evidence to support listing periodontitis as a risk factor for cardiovascular disease, over the traditional Framingham risk factors They felt it was wrong (and could be harmful) to list periodontitis as a risk factor for cardiovascular disease.6
I have tremendous respect for individuals and companies who do not distort the truth for philosophical reasons or personal gain. How can dental hygienists detect scientific spin-doctoring?
- Read systematic reviews and meta-analyses in peer-reviewed journals on given topics and be wary of speakers/writers who focus on single studies.
- Read evidence-based journals, such as the Journal of Evidence Based Dentistry, the Journal of the American Dental Association or the Journal of Evidence-Based Dental Practice where you can find reliable information to help you make more informed decisions.
- Demand transparency (full disclosure) from speakers at dental conventions.
- Support the addition of EBDM to dental hygiene curricula.
- Be skeptical of product claims that are unsupported by high level evidence, such as randomized controlled clinical trials.
Dr. Rethman is entitled to his opinion. His comments about my being uninformed about modifications to the AHA press release and overlooking what associative studies mean clinically, however, were wrongly suggested. The press release itself (Table 1) is not “evidence.” The systematic review leading to the AHA statement is high-level evidence. My column in July 2012 involved examination of the AHA review.
I encourage all dental hygienists to challenge anyone’s opinions. Most importantly, use evidence-based science to argue your point. Of course, to fight misinformation on outcomes of clinical studies one must understand what makes “good evidence” and be knowledgeable about elements in studies that reflect low-level evidence. That is the objective of my columns, and I work hard to inform readers what to look for and consider.
Certainly a published statement from the AHA — based on a systematic review of the literature by many physicians, dentists, and researchers — is reliable evidence.
In sorting through everyday “lies, damn lies, and statistics” always consider the source and unknown motivations. RDH
1. Kotsovilis S and Slim LH. Periodontal and cardiovascular diseases: statistical or causal association? A review and analysis using Hill’s criteria for causation. Can J Dent Hygiene 2012; 46 (2): 131-142.
2. Sackett DL. The arrogance of preventive medicine. CMAJ Aug 20, 2002; 167(4): 363-364.
4. Humphrey LL, Fu R, Buckley DI, Freeman M, Helfand M. Periodontal disease and coronary heart disease incidence: a systematic review and meta-analysis. J Gen Intern Med. 2008;23:2079–086.
5. Beck JD et al. The periodontitis and vascular events (PAVE) pilot study: adverse events. J Perio 2008; 79(1): 90-96.
6. U.S. Preventive Services Task Force (USPSTF). Using nontraditional risk factors in coronary heart disease risk. Ann Intern Med. 2009; 151: 474-482.
American Heart Association Scientific Statement
Despite popular belief, gum disease hasn’t been proven to cause http://www.heart.org/HEARTORG/Conditions/Cholesterol/WhyCholesterolMatters/Atherosclerosis_UCM_305564_Article.jsp">atherosclerotic heart disease or stroke, and treating gum disease hasn’t been proven to prevent heart disease or stroke, according to a new scientific statement published in Circulation, an American Heart Association journal.
Keeping teeth and gums healthy is important for your overall health, but current data don’t conclusively indicate whether regular brushing and flossing or treatment of gum disease can cut the incidence of atherosclerosis, the narrowing of the arteries that can cause heart attacks and strokes.
That conclusion represents what we know right now — it doesn’t mean a link won’t be identified in the future, because many observational studies have noted associations between gum disease and cardiovascular disease. Observational studies are not designed to determine cause and effect — instead, they look at subjects to see if they have a relationship or association.
Gum disease and cardiovascular disease both produce markers of inflammation such as C-reactive protein, and share other common risk factors as well, including cigarette smoking, age and diabetes mellitus. These common factors may help explain why diseases of the blood vessels and mouth occur in tandem, but the association between gum disease and cardiovascular disease appears to exist independent of these risk factors in many studies.
For more than a century, doctors have proposed that infected gums lead to systemic problems like atherosclerotic heart disease, and that mouth bacteria frequently enter the blood stream during dental procedures and during naturally occurring events such as tooth brushing.
Statements that imply a cause-and-effect relationship between periodontal disease and cardiovascular disease, or claim that dental treatment may prevent heart attack or stroke are “unwarranted,” at this time, the statement authors said.
The American Dental Association Council on Scientific Affairs agrees with the conclusions of this report and the World Heart Federation endorsed the statement.
Past RDH Issues