Research Method

The SYSTEM initiative

Systematic Review initiative for Evidence-based Minimum Intervention in Dentistry

SYSTEM’s research method is based on the epistemological understanding that truth of any proposition is plausible if and only if radical scepticism (= the stance that proof of any proposition is not possible as every proof requires for itself proof thus resulting in an infinitive regress of proof that is incapable of proofing anything) towards such proposition can sufficiently be refuted.

By adaptation of Coherence theory, sufficient refutation of scepticism is achieved through multiple, coherent and mutually supportive evidence. Empirical evidence from systematic reviews is considered to be the most objective source for clinical evidence in health care. Therefore, SYSTEM considers that closest possible approximation to the truth of any clinical proposition is given through evidence from systematic reviews to several interrelated topics with results that are mutually supportive (= coherent).

Against this background, the work of SYSTEM is focused on conducting systematic reviews to interrelated aspects per clinical topic. SYSTEM champions quantitative above qualitative synthesis as it provides opportunities for detecting statistically significant treatment effects and improves precision of effect estimation by quantifying their outcomes. Thus quantitative collation of clinical information from separate trials (with or without meta-analysis) covering a particular treatment approach and comparison of materials used provides a more objective assessment of the currently available evidence.

There is still a general lack of randomised control trials (RCT) in dentistry (as compared to medical topics) and therefore SYSTEM has departed from the common approach of strictly considering RCT’s for review, only. In this way lack of accepted trials for review and thus lack of information concerning the current status quo of clinical is avoided. Instead, SYSTEM has adopted a 2-way approach regarding the precision and internal validity of available clinical evidence from controlled trials:

1. To identify and describe the status quo of current clinical knowledge to a specific topic as precise as possible (i.e. What is known?);
2. To judge this current body of knowledge on basis of its internal validity (i.e. How certain is what is known?) and on this basis to (i) derive from it any existing limitations that are to be addressed in future research and (ii) (hopefully) be able to advise the clinician regarding the current status quo.

In the judgement of internal validity of RCTs, SYSTEM’s focus lies on the risk assessment of selection- performance/detection- and attrition bias. In regard to assessing selection- performance/detection bias, SYSTEM has also departed from the common practice and adopted stricter criteria. These criteria do include the common focus on

Adequacy of reported attempts for bias control but also includes focus on Adequacy of reported results of attempts for bias control.

In regard to assessment of attrition bias, the SYSTEM approach follows the quantitative method of sensitivity analysis by computation of assumed worst-case scenarios / clinical outcomes for study subject that have been lost to follow-up in the reviewed trials. This method was developed in collaboration with the help of Prof Paul Fatti from the School of Statistics & Actuarial Science, University of the Witwatersrand.

The above stated methods are novel to common systematic review methodology and have been applied successfully in SYSTEM’s systematic review articles that were accepted in international peer-reviewed dental journals. Besides the adoption of these novelties, SYSTEM’s methodology is based on common consensus for systematic reviews, i.e. as represented by the Cochrane collaboration and its reporting follows recommendations of the PRISMA statement.