ASSESSMENT OF A CASE MIX TOOL FOR STRATIFICATION OF …

Dr Trudy Lin1,2; Associate Professor Sharon Liberali1,2; Dr Mark Gryst2

(1) School of Dentistry, The University of Adelaide (2) Adelaide Dental Hospital, South Australian Dental Hospital

INTRODUCTION

OBJECTIVES

METHODOLOGY CONCLUSIONS

The specialist-performed stratification of publicpatients with disability in South Australia resultedin a low rate of re-referral (2%), demonstrating thatpatients were appropriately stratified.

While both the British Dental Association case mixtool and simplified case mix tool demonstratedagreement with the specialist-performedstratification of patients with disability, the BritishDental Association case mix tool had higherreliability in replicating the specialist-performedstratification.

The British Dental Association case mix tool andsimplified case mix tool can both be used toidentify patient-related factors associated withthe potential need for adjunct measures in theprovision of oral healthcare. The BDA case mixtool is also able to predict legal or ethical patientvariables necessitating the need for oral sedation.

The British Dental Association case mix tool isappropriate to use as a stratification tool bycommunity based dentists within the SouthAustralian Dental Service, to identify patients witha disability who would benefit from referral to theSpecial Needs Unit of the Adelaide Dental Hospitalfor oral healthcare provided by either a specialneeds dentistry specialist or general dentistexperienced in SND.

ASSESSMENT OF A CASE MIX TOOL FOR STRATIFICATION OF PUBLIC DENTAL PATIENTS WITH DISABILITY IN SOUTH AUSTRALIA

REFERENCES

Objective 2 results:The simplified case mix tool weighted Fleiss’ Kappa was 0.51,according to Landis and Koch6, this is moderate agreement.The British Dental Association case mix tool weighted Fleiss’Kappa was 0.65, this is substantial agreement.

Objective 1 results:The specialist-performed stratification of patients with disabilityinto three treating clinician groups: Special needs dentistryspecialist (severe complexity), general dentist experienced inSND in the Special Needs Unit (moderate complexity) and SNDupskilled community dentist (mild complexity); demonstrated a2% re-referral rate (3 of 131 records analysed).

1. Assess the specialist-performed complexitystratification of public patients with disability inSouth Australia completed in August 2016.

2. Compare the reliability of the British DentalAssociation case mix tool (Figures 1, 3, 4) andsimplified case mix tool (Figure 2) in replicating thespecialist-performed stratification.

3. Identify patient-related factors associated withrequiring adjunct measures for oral healthcare(for example, general anaesthesia).

Ethics approval was obtained from the HumanResearch Ethics Committee of the Central AdelaideLocal Health Network to undertake retrospectiveanalysis of dental records of 131 patients on thedisability recall list at the Adelaide Dental Hospital,comparing the specialist-performedstratification with results obtained using theBritish Dental Association case mix tool andsimplified case mix tool.

Inclusion criteria:Patients with a disability referred to the SpecialNeeds Unit and on the recall list from August 2016.Patients who had attended an appointment sincereferral to a general dentist experienced in SND atthe Special Needs Unit (moderate complexity) or toa SND upskilled community-based dentist (mildcomplexity).

Exclusion criteria:Patients with more than two criteria rated as 0due to insufficient information in the clinicalrecords.Patients without a full medical history within thelast two years.Patients previously under the care of theprimary investigator to ensure objectivity in thetool’s assessment.

Objective 3 results:Univariate binary logistic model results demonstrated sixstatistically significant variables (predictors) associatedwith the need for adjunct measures demonstrated in Table 1.

1. Australian Bureau of Statistics. Disability, Ageing and Carers, Australia: Summary of Findings 2018. URL: https://www.abs.gov.au/ausstats/abs@.nsf/mf/4430.0. Date Accessed 18-1-20

2. Dental Board of Australia. Statistics: Registrant Data 2020. URL: https://www.dentalboard.gov.au/About-the-Board/Statistics.aspx. Date Accessed 26-6-20

3. NHS England. Guide for Commissioning Special Care Dentistry. Periodical Guide for Commissioning Special Care Dentistry. URL: https://www.england.nhs.uk/commissioning/wp-content/uploads/sites/12/2015/09/guid-comms-specl-care-dentstry.pdf

4. Bateman P, Arnold C, Brown R, et al. BDA special care case mix model. British Dental Journal 2010; 208:291-296

5. Duane B, Gordon K, Freeman R, Humphris G, Richards D, O Keefe E. Weighing up the Weighted Case Mix Tool (WCMT) : a psychometric investigation using confirmatory factor analysis, 2014

6. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159-174.

Suzanne Edwards, Senior Statistician at the University ofAdelaide and the South Australian Dental Service for grantingpermission to conduct this research at the Special Needs Unit ofthe Adelaide Dental Hospital.

ACKNOWLEDGEMENTS

CASE MIX TOOLS

Figure 1: BDA CMT scoring system Figure 2: Simplified case mix tool4 scoring system*

*To enable comparison of the case mix tools in statistical analysis, scores were assigned to sCMT letters: 0 and A as the same value and B/C the average of B and C values of the BDA CMT

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Dr Trudy Lin is completing a Doctor of Clinical Dentistry inSpecial Needs Dentistry at the Adelaide Dental School,University of Adelaide, and is a senior dental officer in theSpecial Needs Unit, Adelaide Dental Hospital.Contact: trudy.lin92@gmail.com

Table 1: Univariate binary logistic model results: statistically significant variables

Statistical Analysis

Objective 1: Frequency ofparticipants referred to a differentcomplexity group.

Objective 2: Fleiss’ Kappa tocalculate reliability of the case mixtools in allocating participants to thesame complexity as the specialist-performed stratification.

Objective 3: Univariate binarylogistic models to determineassociations between patientcomplexity, case mix tool criteria anduse of adjunct measures.

RESULTS

Figure 4: Complexity band categorisationFigure 3: Narrative to score BDA CMT “Ability to cooperate” criteria

The British Dental Association case mix tool consists of a structured matrix with patient-related parametersaffecting complexity of providing oral healthcare. Each parameter contains a detailed narrative to assist assigning acomplexity score4 (example shown in Figure 3). The scoring is measured on a four point scale with zerorepresenting no complexity and A, B and C representing increasing levels of complexity. The total score categorisesthe patient into different complexity bands (Figure 4). The simplified case mix tool was developed followingpsychometric investigation conducted by Duane et al5 where the oral factors parameter was omitted as it did notadd to reliability, score weighting was removed and complexity was collapsed into a three-point scale (figure 2*) toallow more efficient use.

All individuals have a right to equal access to oralhealthcare. In Australia, 17.7% of the population arereported to live with a disability1 and 5.7% haveprofound or severe disability1 however there is aundersupply of special needs dentistry (SND)specialists.2 Individuals with mild to moderatedisabilities may benefit from accessing public dentalservices within their local community.

In August 2016 a specialist-performedstratification of patients with disability at the SpecialNeeds Unit of the Adelaide Dental Hospital wasconducted. Patients were divided into three groupsbased on their dental records. Severe complexitypatients remained under the care of a specialist,moderate complexity patients were referred to ageneral dentist experienced in SND at the SpecialNeeds Unit, and mild complexity patients werereferred to a community-based dentist who had beenupskilled in SND.

The premise of this study was to assess use of acase mix tool to stratify patient complexity in aformalised, objective and reproducible way, tosupport implementation for SND upskilled communitydentists to utilise as a referral tool for specialistcare, thereby improving access to appropriatelyskilled dentists for individuals with disability.

The British Dental Association case mix tool (BDACMT) and simplified case mix tool (sCMT) wereselected for investigation as the oral healthcaredelivery model for Special Needs Dentistry in SouthAustralia resembles the National Health System inthe United Kingdom3, where the tools have beenwidely implemented. This study is the first to explorethe use of the BDA CMT in Australia, and the first toinclude the sCMT.