After rather devastating negative conclusions made in a systematic review (SR) of the literature regarding the long claimed, possibly causal, relationship between periodontitis and atherosclerotic vascular disease by Lockhart et al. (2012), a highly alerted group of members of our specialty organizations, the Amercian Academy of Periodontology and the European Federation of Periodontology, had hastily organized a joint workshop, in the end of 2012, to fix unwelcome results of a number of large intervention studies by creating new systematic reviews on the Perio-Systemic link. The clear aim was to cement, once and forever, the claim of the number one clinical problem: periodontal disease and general health are closely related.
While the proceedings had been published, open access, in special issues of our main professional journals, the Journal of Clinical Periodontology and the Journal of Periodontology, workshop participants of the EFP presumptuously condensed the 209 pages of the 16, mostly valuable, papers in a nutshell, strangely called Manifesto.
An enthusiastic opinion piece (erroneously designated Systematic Review) has just appeared in the August issue of the prestigious Journal of Clinical Periodontology (Miron et al. 2016). The 16 pages are authored by a remarkable number of 20 authors.
This is certainly not a systematic review as basic PRISMA requirements are not met. Not a single one. So, has this to be regarded just another old fashioned narrative review? I can’t help but when reading the first authors’ unwarranted zeal this may actually be just another brazen commercial. I am afraid that most if not all authors are listed on Straumann’s pay roll, the company which currently markets Emdogain. Thus, the required (for biomedical journals) Conflict of interest and source of funding statement sounds, well, frivolous.
The authors report no conflict of interest for the present review article. No funding was required [sic]/received by any of the co-authors for the present review article.
According to his CV, Dr. Miron alone received 270,500 CHF ($274,246) from Straumann between 2010 and 2015.
As the authors dare to suggest recommendations (called guidelines, however except a flow chart in the main text, see below, they are deeply buried in the paper’s supplement which can be accessed only online) without grading the presented evidence from randomized controlled and observational studies, it seems pertinent to judge, at least in part, whether respective suggestions have a sound scientific basis.
Claims and denials of clinically relevant effects of, in particular, non-surgical periodontal treatment on markers of diabetic control have not only led to a surge of new randomized clinical trials and systematic reviews thereof. If anybody had hope that the current frenzy has found a happy end with the updated and very comprehensive Cochrane review by Simpson et al. (2015) (s)he has been mistaken. In the June issue of the Australian Dental Journal, Botero et al. (2016) report on an umbrella review in which they systematically reviewed all systematic reviews on the subject, be it with or without meta-analysis, published between 1995 and 2015. The paper has been accepted for publication on January 20, 2016. It has to be emphasized that using the term “umbrella review” is somewhat misleading. In a strict sense, an umbrella review assembles together several systematic reviews on the same condition in the presence of many treatments or many important outcomes.
What might lead to a Eureka! moment among our scientific and professional community should rather be seen as matter of serious concern. The two recent papers on teeth, or rather lack thereof, and possible relationship with cardiovascular events or even death have sparked the expected excitement. In one editorial of a Dutch heart journal, the editor-in-chief even trumpets in the title of his editorial, “Tooth brushing for a longer and healthier life.” He thus repeats, in other words, the notorious Floss or die! claim of 1996. I had forecast, some time ago, that relentlessly beating the drum by our thought leaders will ultimately lead to loss of any interest of the medical profession (in particular cardiologists) in the perio-systemic link, in particular as the American Heart Association had already concluded, in their comprehensive systematic review of 2012, that
[e]xtensive review of the literature indicates that PD [periodontal disease] is associated with ASVD [atherosclerotic vascular disease] independent of known confounders. This information comes mostly from observational studies, however, and therefore does not demonstrate that PD is a cause of ASVD, nor does it confirm the contention that therapeutic periodontal interventions prevent heart disease or stroke or modify the clinical course of ASVD. Although a contribution of PD to ASVD is biologically plausible, periodontal and cardiovascular diseases share multiple risk factors that are prevalent and powerful promoters of disease, including tobacco use, diabetes mellitus, and age. (Emphasis added.)
What do statistical significance and clinical relevance actually mean? To be clear, that the American Journal of Periodontology has decided to accept another educational paper for clarifying common misconceptions is of course a good idea. The journal is mainly read by practicing periodontists who may not be so much familiar with statistics in general. What Chambrone and Armitage actually deliver (the accepted paper has just gone online in JOP) is, however, disappointing. Most scientists will probably stop reading after the first sentence of the second paragraph. Kannste vergessen.
It has been unmistakably demonstrated that statistically differences (e.g., P-value < 0.05) are more likely to be detected with large sample sizes compared to small ones.1-3,11