Classification of periodontitis, comparison of the 1999 and the 2017 versions.
Justification for the 2017 periodontitis classification in the light of the Checklist for Modifying Disease Definitions: A narrative review
https://doi.org/10.1111/cdoe.12856
, . Justification for the 2017 periodontitis classification in the light of the Checklist for Modifying Disease Definitions: A narrative review. Community Dent Oral Epidemiol. 2023; 51: 1169–1179. doi:10.1111/cdoe.12856
This article was brought to my attention by my regular following https://twitter.com/CommDentOralEpi, I recommend it.
Diagnosis and treatment of periodontitis, and now also periimplantitis, is a truly relevant subject engulfing treatment planning, treatment prognosis and funding.
This paper describes the conundrum of clinical decision making experienced by most dental clinicians.
In the view that Norwegian National Health Insurance refunds treatment of periodontitis and consequences with a sum of 469 million NOK, 35% of total refund to dental health, it should be of major interest to the profession and the public that the appropriate level of diagnosis periodontitis is being utilized.
Obviously presently it is not.
This is a rundown of quotes from the article. I recommend it to be read.
The abstract says:
Once a while, disease classifications have needed revision because new knowledge has accumulated, and new technologies and better treatments have emerged. Changes made to disease classifications should be trustworthy and openly justified. The periodontitis definition and classification system was changed in 2017 by the ‘World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions’ Read more
The workshop, comprising clinicians and researchers, resulted in the pro-duction of a 23-article special issue that introduced the new definitions and classifications of periodontitis. In this narrative review, we critically review how the changes made to the periodontitis definition and classification were justified in the light of the Checklist for Modifying Disease Definitions. Read more
1WHAT ARE THE DIFFERENCES BETWEEN THE NEW DEFINITION AND THE PREVIOUS DEFINITION?
The major changes from the 1999 periodontitis classification18 to the 2017 periodontitis classification are shown in Figure 1.
3 HOW WILL THE NEW DISEASE DEFINITION CHANGE THE INCIDENCE AND PREVALENCE OF THE DISEASE?
The impact of the new classification on the estimated incidence or prevalence of periodontitis was not considered in the documents, and we were not able to find any discussion on the estimated changes in the prevalence and incidence of periodontitis as a result of a change of classification. One reason may be that the lack of clear and operational diagnostic criteria for ‘aggressive’ and ‘chronic’ periodontitis in the 1999 classification. Read more
4 WHAT IS THE TRIGGER FOR CONSIDERING THE MODIFICATION OF THE DISEASE DEFINITION?
The view was also held by the workshop that clinicians would need ‘additional information beyond the specific form of periodontitis and the severity and extent of periodontal breakdown […] to more specifically characterize the impact of past disease on an individual patient’s dentition and on treatment approaches needed to manage the case.’15
Periodontitis is defined as an ‘inflammatory disease associated with dysbiotic plaque biofilms’.17 Observations of the presence of CAL in the absence of increased probing depths and inflammation were clearly challenging for users of the 1999 classification,26 and the 2017 classification system response to this was a definition of a ‘periodontitis case’ based on interdental CAL or on buccal/oral CAL only when ‘the observed CAL cannot be ascribed to non-periodontitis-related causes Read more
5 HOW WELL DOES THE NEW DEFINITION OF DISEASE PREDICT CLINICALLY IMPORTANT OUTCOMES COMPARED WITH THE PREVIOUS DEFINITION?
Overall, the evidence on the predictive ability of proposed classification is indirect because it has not been shown that the proposed classification would be better in predicting clinically important outcomes than the old(er) classification(s). Whether having periodontitis diagnosed using the 2017 classification will benefit a patient by assisting in understanding the risk of future clinically important events,4 remains unknown.27–29
Read more
6 WHAT IS THE REPEATABILITY, REPRODUCIBILITY AND ACCURACY (WHEN ESTIMATIONS ARE POSSIBLE) OF THE NEW DISEASE DEFINITION?
The repeatability or reproducibility of the new classification system does not seem to have been given in-depth consideration. Repeatability or reproducibility of some clinical parameters were considered in rather general terms.
One of the key purposes of the new 2017 classification was to achieve good clinical utility, which was one of the problems with the 1999 classification.6, 26, 30 Because classifications with poor precision result in inconsistent classification of patients and have poor clinical utility,4 it is noteworthy that the repeatability or reproducibility of the new classification system was not given any deeper consideration Read more
Even so, the new 2017 classification requires the collection of multiple less-than-perfect clinical parameters,31–37 including probing depth recordings, reasons for missing teeth or assessment of the causes of the CAL and radiographic measurements, in order to correctly determine the extent, stage and grade of periodontitis among their 36 possible combinations (4 stages × 3 extents × 3 grades). It is therefore not surprising that later studies imply that the 2017 classification has less-than-perfect inter-examiner reliability.38–41
Read more.
7 WHAT IS THE INCREMENTAL BENEFIT FOR PATIENTS CLASSIFIED BY THE NEW DEFINITION RATHER THAN THE PREVIOUS DEFINITION?
The new classification system was thought to result in incremental benefits, because it provides knowledge on ‘important dimensions of an individual’s disease, including the complexity that influences approach to therapy, the risk factors that influence likely outcomes, and level of knowledge and training required for managing the individual case.’15
Read more.
Even so, the workshop could have explained in more detail how the desired benefits are concretely achieved. Disregarding for the moment the consequences of the unknown predictive abilities, and the largely unknown repeatability and reproducibility of the 2017 classification, there are, in our view, two major issues that limit the incremental benefits achievable with the 2017 classification.
- The majority of periodontitis patients have a low risk of experiencing patient-important outcomes. Most periodontitis cases belong to Stages I or II (initial or moderate severity and complexity), and they are likely to have a low risk of patient-important outcomes over their life course.13–15, 43 This means that the incremental benefits (or losses) with (or without) treatment are likely to be minor for most patients regardless of the classification adhered to.4
- Guidance in choosing treatments. It is unclear to us how the classification will help choosing better care for people with periodontitis. The first-line professional therapy for all periodontitis cases has since long included oral hygiene instructions and anti-infective therapy as well as risk factor identification and control.6, 44 Even though it may be possible ‘to achieve clinical outcomes that were not previously possible’ with ‘new technologies and therapeutic approaches’,15 decisions about their use to treat and monitor people with periodontitis are based on weak evidence.44–48
8 WHAT IS THE INCREMENTAL HARM FOR PATIENTS CLASSIFIED BY THE NEW DEFINITION RATHER THAN THE PREVIOUS DEFINITION?
Harms associated with the use of the new classification system were not at all considered in the investigated documents.
Given how harms are considered in medical49, 50 and dental research,51, 52 as well as in the introduction of new disease definitions in medicine,3, 10 this neglect of possible harms was not a surprise. Related to the periodontitis classification, a few potential harms of the new classification system could nonetheless have been considered.
Unfortunately, service providers may have a conflict of interest here as the costs for patients and society are their incomes. Finally, any modifications to classifications are likely to cause incremental costs and resource use related to new diagnostic, treatment and follow-up practices.4 Taking into account the above considerations, it is not surprising that significant additional education, training and calibration are considered necessary due to the introduction of 2017 classification.40
Read more.
9 WHAT ARE THE NET BENEFITS AND HARMS FOR PATIENTS CLASSIFIED BY THE NEW DEFINITION RATHER THAN THE PREVIOUS DEFINITION?
No explicit evaluation of net benefits and harms for patients was given in the documents. However, as described above, the new classification was considered to have some incremental benefits, while no harms were stated. Therefore, it seems the workshop saw the new definition as net beneficial.
In the above discussion, we have not considered the economic harms (to the patients) and benefits (to the clinicians) of overdiagnosis, but such considerations should certainly also be taken into account, both at the individual and the societal level.
10 DISCUSSIONS
Our findings related to the introduction of 2017 periodontitis classification are in agreement with what has been reported by researchers on the changes to definitions of high blood pressure and attention deficit/hyperactivity disorder (ADHD).79, 80 For instance, researchers, who investigated the changes made to Diagnostic and Statistical Manual of Mental Disorders (DSM-5) concerning ADHD, found that ‘no evidence was used by, or available to the [DSM-5] Committee regarding the impact on prevalence […] or the effect of the criterion changes on diagnostic precision, the prognosis of, or the potential benefits or harms for individuals diagnosed by the new, but not old criterion.’79 Thus, the challenges we detected in the introduction of the new periodontitis classification are not unique.
As previously mentioned, the Global Burden of Disease Study applied a rather lax definition of ‘severe chronic periodontitis’,67 and a recent Global Oral Health Status Report by WHO9 simply stated that ‘Only severe periodontal disease, defined as the presence of a pocket of more than 6 mm depth, is a condition of public health concern.’ The number of years lived with disability from periodontitis is used to represent the public health impact of periodontitis, again with a reference to the Global Burden of Disease Study.8
Even so, we can conclude that most of questions in the Checklist for Modifying the Definition of Diseases4 were not considered in the documents introducing the 2017 periodontitis classification. Moreover, to a large extent it remains unknown whether the new periodontitis definition and classification system is the best available system for all users within the clinical, research or epidemiological realms or for the patient and community stakeholders. People and societies deserve transparent and balanced assessments of potential benefits and harms associated with the periodontitis classification, which should also reflect the values and preferences of both patients and the wider community and consider the impact on resource usage. Read more.