Screening for Type 2 Diabetes Mellitus initiated through the dental setting: a cost-effectiveness analysis
AffiliationMelbourne Dental School
Document TypePhD thesis
Access StatusOpen Access
© 2019 Alagesan Chinnasamy
Background. Diabetes Mellitus (DM) is the fastest growing chronic condition in Australia. Approximately, 30% of DM in Australia is undiagnosed. Early identification may delay or prevent the onset of DM with minimal complication. In the Western Pacific (WP) region, Australia has the highest per capita spending on DM. With the rising cost of healthcare, increasing emphasis is being made to ensure that health interventions are not only practical but also cost-effective that can save resources which otherwise may have to be spent on complication and hospital admission. By stretching the number of contact points between health care providers and individuals seeking care, there is plenty of opportunity for early identification of asymptomatic individuals with Type 2 Diabetes Mellitus (T2DM). With this link between DM and periodontal disease, dentists may have an unrealized opportunity to identify risk groups and refer them to physicians for further care. For any screening activity in the dental setting, the participation of Oral Health Professionals (OHP) is important. Little is known as to how well oral health professionals incorporate into practice on the evidence supporting the link between DM and periodontal disease. Besides that, no previous studies have reported the cost-effectiveness of opportunistic screening using a diabetes risk assessment tool in the dental setting. As such, the aim of the thesis is twofold. To explore the Victorian oral health professionals (OHP) knowledge, attitude and practice (KAP) around DM and to evaluate the overall economic justification of screening for diabetes and pre-diabetes in the dental setting. Methods. A cross-sectional survey of Victorian OHP was conducted. The questionnaire consisted of sociodemographic, practice characteristics and diabetes-related KAP. Descriptive statistics with frequencies and percentages were used to summarize the variables. A Mann-Whitney and Kruskal-Wallis test was performed to determine differences in OHP response to the KAP questions. The screening model consists of a decision tree and a disease progression Markov model to identify the risk of T2DM over a ten-year period. Literature data were used for the risk categorisation and disease transition for health states. The cost-effectiveness of screening was compared to no screening option. A hypothetical population of 40 to 74-year-old Victorian dental patients with no previous history of DM were screened with the Australian type 2 Diabetes Risk Assessment Tool (AUSDRISK). Those identified as high-risk follow-up with the physician for screen diagnosis using Fasting Plasma Glucose (FPG). Based on the previous finding from two-step screening in the dental setting the model made an assumption that 21.5% of the dental patient identified as high risk follow up with the physician. The cost-effectiveness was analysed from a societal perspective. The main outcome measure includes cost per case detected as undiagnosed T2DM, new cases of T2DM. A univariate sensitivity analysis was performed to determine the effect of different physician follow-up rate from the dental setting to identify undiagnosed T2DM. Results. The survey analysis included 197 OHP. General and specialist dentist constitute 65% and 11% of the response and the remainder were dental hygienist and therapist. Around 86% of the OHP showed adequate knowledge of DM. Further 93% and 81% of the OHP expressed positive attitude and practice behaviour towards T2DM screening and management. For OHP to perform chair-side screening for DM, 58% felt it was essential, and 70% felt it was appropriate. More female (67%) and public sector OHP (79%) felt it is important to conduct chair-side screening for T2DM. The majority (65.4%) of the OHP agreed on consent as the most important and insurance coverage as the least important (43%) consideration for T2DM screening. Under model assumption, the number of dental patients identified as undiagnosed T2DM and pre-diabetes were 4,108 (0.3%) and 10,072 (0.8%). The cost incurred for one new case of undiagnosed T2DM and pre-diabetes were AUD 15,508 and AUD 6,325. The Number Needed to Screen (NNS) to identify one new case of undiagnosed T2DM and pre-diabetes were 288 and 117. Among those followed up with the physician, at the end of five years, 81.5% had Normal Glucose Tolerance (NGT), 8.1% had Impaired Fasting Glucose (IFG), 6.9% had T2DM, and the all-cause mortality was 3.5%. At the end of the ten-year period, 10% had T2DM. The overall and disease-free survival was 92.8% and 82.8%. Discussion. Majority of OHPs had adequate knowledge and a positive attitude towards T2DM screening in the dental setting. The survey identified patient willingness as the most important consideration among the OHPs for implementing T2DM screening in the dental setting. The screening model identified several methodological challenges due to incongruent data and unsuitable comparator. Despite that, opportunistic screening with AUSDRISK was found to be neither clinically effective nor cost-effective compared to screening in the medical setting. High screening cost, poor predictive ability of AUSDRISK, low prevalence of the disease, unnecessary physician referral besides uncertain benefits, fear of over diagnosis and poor patient compliance makes screening for T2DM in the dental setting difficult to justify. The model findings are in line with previous estimates on AUSDSRISK as a screening tool. In financially constrained health system resource allocation will need to be based on favourable evidence that screening can reduce disease levels in the community, demonstrate health benefits at an acceptable cost. A two-step opportunistic screening that includes a risk assessment followed by a Point-of-Care (PoC) HbA1c may offer some benefits in the low- and middle-income countries.
KeywordsAustralia; diabetes; pre-diabetes; screening; dentist; oral health professionals; risk assessment; economic evaluation; cost-effectiveness; Markov modelling; opportunistic; knowledge; attitude; practice; HbA1c; AUSDRISK
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