In a recent analysis of thousands of randomized controlled trials (RCT) in eight journals a simple method was offered which might enable skeptical scientist identification of data fabrication. Editor of the Anaesthesia journal John B. Carlisle of Torbay Hospital, UK, looked at baseline differences of means in more than 5000 randomized controlled trials, mainly in the field of Anesthesiology, but also more than 500 published in JAMA and more than 900 published in the New England Journal of Medicine . His study went online earlier this week. Analyzed articles were published between 2000 and 2015. In brief, if randomization was successful, baseline differences should be small. Giving p-values for baseline differences (in order to indicate successful randomization) is actually discouraged since they are not really interpretable, but Carlisle calculated them anyway. If the null hypothesis is true, p-values have a uniform distribution. So p-values between 0 and 1 would be equally likely.
Last weekend, EFP and International Diabetes Federation (IDF) delegates, in partnership with Sunstar, had met in Madrid and had worked on guidelines for dentists, medical doctors and patients with periodontitis and/or diabetes. The EFP website features some key findings when reviewing the literature. In particular, it is claimed that,
evidence suggests that periodontitis patients have a higher chance of developing pre-diabetes and type-2 diabetes and that people with periodontitis and diabetes have more difficulty in keeping their blood-sugar levels under control. Furthermore, patients with both diseases are more likely to develop diabetic complications than people with diabetes without periodontitis.
Current evidence indicates that in people with diabetes, periodontal therapy accompanied by effective self-performed oral hygiene at home is both safe and effective – even in people with poorly controlled diabetes. Similarly, there is consistent evidence that periodontal therapy reduces blood-sugar levels in people with diabetes and periodontitis. (Emphasis added.)
According to Dr. Bjarne Klausen from Esbjerg, Danish National Clinical Guidelines for the use of antibiotics in dental practice had recently been finalized. See a quick guide here [pdf]. As regards periodontal infection, he writes,
We formulated a focused question that was in line with the Scandinavian consensus: Should prescription of antibiotics be considered in patients with sufficient oral hygiene, if their periodontal condition does not respond to conventional treatment?
Well, they did not find a single relevant study. How’s that? Isn’t it so that dozens if not hundreds of studies had been performed since the early discovery by Jørgen Slots in Copenhagen identifying an unidentified gram-negative rod in abundance in what was then localized juvenile periodontitis? Soon later it was clear that this bug was Actinobacillus (now Aggregatibacter) actinomycetemcomitans, and that it could best be targeted by systemic antibiotics in conjunction with traditional mechanical/surgical periodontal treatment. Soon after a couple of case series by van Winkelhoff et al. in 1989 and 1992, Amoxicillin plus Metronidazole (the infamous “van Winkelhoff cocktail”) became extremely popular and has since then been mentioned in national guidelines for the treatment of severe periodontitis where A. actinomycetemcomitans could be found in abundance.
In a recent commentary in the Journal of Periodontology, Merchant and Josey (2016) had suggested directed acyclic graphs to better comprehend the partly conflicting results from randomized controlled trials (RCT) on diabetic control after periodontal treatment in diabetic patients. In particular the influence of obesity caught their attention.
As a matter of fact, a remarkable number of systematic reviews (whose varying quality have recently been reviewed in at least two further SRs of SRs) have shown that numerous small-scale, single-center, often poorly designed RCTs had shown that the marker for diabetic control, HbA1c, might be reduced by, say 0.4% 3 months after in essence non-surgical periodontal therapy. The only large-scale, multi-center trial (DPTT) by Engebretson et al. (2013) couldn’t confirm that, though, which sparked harsh criticism of a large number of our thought leaders. A professor in the Department of Epidemiology and Biostatistics at the University of South Carolina, Columbia, Dr. Anwar Merchant himself had written a letter to the editors of JAMA pointing first to the fact that most participants in the paper by Engebretson et al. were utterly obese. He had further noticed that, “[i]n RCTs conducted among mostly nonobese individuals, periodontal treatment has been shown to reduce systemic inflammation2,4 and improve glycemic control among those with type 2 diabetes.2 However, periodontal treatment has not been shown to affect glycemic control in RCTs conducted among predominantly obese individuals with type 2 diabetes.1,3”
Obesity is positively correlated with inflammatory markers in the blood and strongly related to insulin resistance and metabolic dysregulation mediated by chronic systemic inflammation.5 These findings, taken together with results from RCTs evaluating the effects of periodontal treatment, suggest that the lack of effect of periodontal treatment on glycemic control observed in the study by Engebretson et al may be attributed to the high level of obesity in the study population. Therefore, the findings may be generalizable only to predominantly obese populations with type 2 diabetes.
The EFP website has posted the other day a debate between Professors Lior Shapira of the Jerusalem Hebrew University and Andrea Mombelli, Geneva. Is it time to rethink on the use of antibiotics in the treatment of periodontitis? Well, it actually is. One cannot continue just emphasizing the undeniable (if short-term) effect of antibiotics reducing the need and extent of periodontal surgery when administered as an adjunct to non-surgical treatment (Mombelli) without having the much bigger picture (real global threats of antibiotic resistance development) in mind (Shapiro). I have written about recent respective clinical reports on (transient) effects of adjunct antibiotics numerous times on this blog, see, for example here, here and here. I never concealed my opinion. Biofilm infections are indeed different.