Dental considerations in minimizing osteoradionecrosis in head and neck cancer patients : Delphi-derived factors for a decision analysis

Osteoradionecrosis (ORN), a potential complication in head and neck cancer patients irradiated at high doses, can have severe consequences on patient quality of life and costs of treatment. Teeth can never be extracted from irradiated bone without the risk of osteoradionecrosis, but diseased teeth carry a greater ORN risk. The management of teeth so as to minimize the occurrence of ORN, while preserving maximal quality of life for all patients at risk, is a day-to-day problem for dental staff in many oncology treatment centers. Guidelines for the extraction of teeth prior to radiotherapy published by the National Institute of Health and elsewhere in the literature are not exact,1 so additional information, ideally a validated clinical decision analysis on the dental minimization of ORN, or an algorithm or clinical policy deriving from it, would be highly useful. This thesis is a step towards these clinical goals, producing data of immediate clinical interest in addition to data specially suited to ORN epidemiology and decision analysis. The thesis is also justified on methodological grounds. Formal, traditional clinical decision tree analysis of complicated dental treatment dilemmas are very rarely found in the literature, and the incorporation of survey research is uncommon. Thus, this research is exploratory with respect both to the survey process used and its proposed outcomes. Official and semi-official documents indicating appropriate oral management of patients at risk for osteoradionecrosis (NIH 1990; ADA 1989; Barker, Barker, and Gier 1992) do not appear to have utilized formal consensus methodologies to reach their conclusions, and none appeared to provide an opportunity for anonymous dissent from the positions initially presented. This study does not, however, seek to duplicate the implied objective of NIH (1990) (to produce in a living document, general guidelines for clinicians). It primarily seeks, using formal consensus methodology, to examine systematically the assumptions made during preradiotherapy dental intervention decisions, point out weaknesses, indicate considerations relevant to a theoretical decision analytic framework, suggest a theoretical clinical decision analysis, and indicate research necessary to quantify further the decision process. By achieving consensus, the way to create validated decision analyses useful for clinician and patient education and decision support is made clear. Measures proposed in this research are also a step toward validated patient-derived utilities that would facilitate the implementation of decision analysis, cost-benefit, and quality control frameworks. The focus of the eventual theoretical decision analysis, and primary research question for which data are to be identified using a modified Delphi technique, is: "Under what conditions should teeth be extracted within the high dose radiation volume in order to minimize the frequency and severity of ORN?" The Delphi consensus approach was chosen for the Survey because it permitted analysis of responses from a select group of experts, provided anonymity required to minimize intimidation, and it did not require simultaneous geographical proximity of the experts and involvement of a trained panel-discussion facilitator. Open- and close-ended items, scenarios, and rating scales for agreement with Delphi statements and confidence in responses were presented to volunteer experts. 12 of 22 experts solicited from the U.S. and Canada (55%) participated in the Delphi survey, and 4 of 16 in Europe and Australia. (In other words, 28 of 38 experts (74%) solicited for participation in the Delphi Survey agreed to participate. 16 of the 38 (42%) actually returned the 60-page long survey.) The inclusion of the close-ended items in the survey was made practical by the body of literature on the clinical problem. This permitted combination of Delphi rounds one and two and useful comparison of responses; the comparisons generally implied high content validity for the close-ended items. Expert opinion consensus revealed that major risk factors for ORN were Radiation (particularly dose, dose per fraction, the timing of radiation, the osseous volume irradiated to high dose, and the presence or absence of interstitial therapy); Periodontal Status (as assessed using conventional static indicators, e.g. pocket depth); and Endodontic status. Anatomical site { a) mandible; b) posterior part of mandible; perhaps c) proximity of roots to surgical cuts} also were considered by respondents to be highly relevant to ORN risk. The oral hygiene status of the dentition, projected caries rate, patient compliance, and salivary status were considered relevant to ORN risk but are presumed to be mathematically dependent and to need to contribute to the decision analysis as a multifactorial integral indicating their combined ORN risk. Surgical trauma, particular metabolic states, anticipated mandibular perfusion capability, and mucosal friability were considered by respondents to be relevant to ORN risk or the decision to extract, but either they, or their effects, were regarded as difficult to quantify. {Factors proposed for inclusion in the decision analysis were assessed and characterized as to their suitability (i.e., quantifiability, controllability, and degree of independence). This approach was indicated by the natures of the dental variables potentially relevant to the clinical problem.} Only a minority of respondents indicated that hyperbaric oxygen or chemotherapy affected ORN prognosis. These findings may be significant, or artifacts of the survey's design. Close-ended items were not present to prove the reliability of these responses. A decision analysis on ORN-prophylactic tooth extraction should include factors related to the desirability of retaining particular teeth irradiated at high dose. Factors proposed as relevant to this proposed multifactorial utility sub-variable included caries rate, tooth mechanical soundness /restorability, and tooth functionality. The median minimum expert-recommended extraction healing time prior to radiotherapy was 7 days; the median desired time, 14 days (mean, 11.6). Factors integrated in the scales proposed in this study for ORN-associated pain and function were supported as related to quality of life. Pain was regarded the most important factor affecting quality of life, function and pathological fracture were regarded as secondary. (Other factors were suggested and merit further investigation.) Function levels in various ORN categories clearly appear to be associated negatively with pain, suggesting that quality of life utilities could, if only validated pain data were available at some particular time in the future, be related (as an approximation) to pain alone, at first. The clinimetric scale outcome measures suggested in this thesis could be incorporated in frameworks for quality improvement or cost-benefit analysis, although conclusions drawn would be limited by their ordinality and lack of validation. Although all data reported are subject to reliability and validity constraints outlined in the thesis, qualitative data supplied on important topics were quite consistent from item to item, and relatively few (and non-critical) items were associated with low consensus or other proposed indicator of poor data quality. Most quantitative estimates of ORN risk were judged to lack adequate quality and validity, but pain and function assessed in two ways for categorized ORN demonstrated consistency, and seemingly remarkable consistency was present in the extreme ORN categories- ORN3b (progressive ORN with jaw fracture,) and ORNO (patient at risk, no ORN). Cross-impact analysis and other statistical manipulations designed to correct for potential confounders generally were inadvisable due to the small numbers of responses present. A theoretical, introductory decision analysis on the dental minimization of osteoradionecrosis is presented at the conclusion of the thesis. Further research is required before it can be validated and used clinically. Actions advocated to enable this, and to enhance the data base for all future studies on the dental management of ORN, are: 1. Adoption of an identical definition for osteoradionecrosis of the jaws, in future studies 2. Application to the Canadian Institute of Health Information to recommend the adoption by the "International Classification of Diseases" of a specific diagnostic code for osteoradionecrosis of the jaws. 3. Initiation of ongoing collection of epidemiological data for ORN of the jaws from non-experimental data bases employing such definitions. 4. Initiation of further prospective data gathering in patients at risk for ORN, with detailed recording of the treatments employed and the ORN prognostic factors outlined above, and ORN outcomes 5. Adoption of a common standard for categorization of ORN outcomes 6. Integration of existing data on the distribution of categorized ORN severity 7. Assessing expert consensus on the relationships of chemotherapy and hyperbaric oxygenation to ORN rates and healing, anonymously 8. Creation of validated patient-derived outcome scales for osteoradionecrosis 9. Consideration of new decision trees, e.g. on prosthetic or physiological rehabilitation. 10. Refinement of existing decision trees, once the data base improves 11. Validated clarification of interactions and effects of potentially dependent ORN risk variables.

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