1. The cost-effectiveness of providing a DAFNE follow-
up intervention to predicted non-responders
J Kruger1, A Brennan1, P Thokala1, S Heller2
on behalf of the DAFNE Research Group
1 School of Health and Related Research (ScHARR), University of
Sheffield, Sheffield
2 Academic Unit of Diabetes, Endocrinology and Metabolism,
School of Medicine and Biomedical Sciences, University of
Sheffield, Sheffield
Introduction
The Dose Adjustment for Normal Eating (DAFNE) course is a structured education programme for adults with Type 1 diabetes. DAFNE has been found to improve
glycosylated haemoglobin (HbA1c) levels in UK Type 1 diabetes patients1 and a cost-effectiveness modelling analysis concluded that DAFNE was cost-effective2. This
analysis assumed that HbA1c benefit experienced by patients receiving DAFNE was homogeneous, however it has been found that HbA1c response to DAFNE is
highly variable between patients. Although some patients do experience significant HbA1c reductions after DAFNE, other patients experience a worsening of HbA1c
1,3
and some find it difficult to maintain initial HbA1c improvements4. Offering an early ‘follow-up’ intervention to those patients predicted from their initial change in
psychosocial characteristics not to respond to DAFNE in the long term may be cost-effective if additional HbA1c benefit can be gained.
This study aims to explore statistical modelling methodologies to predict individual clinical responses to DAFNE from psychosocial characteristics and incorporate
psychosocial predictors into an economic simulation model to investigate the cost-effectiveness of providing a follow-up intervention to subgroups of predicted non-
responders.
Methods
Data from the National Institute for Health Research (NIHR) DAFNE Research Programme were used to support all analyses*. In the psychosocial sub-study of the
NIHR DAFNE Research Programme demographic, psychosocial and clinical data were collected from 262 patients at baseline and 3-, 6-, and 12-months after
DAFNE.
Two regression models were used to investigate the relationships between initial change (baseline to 3 months) in psychosocial characteristics and 12-month HbA1c
response to DAFNE:
The regression prediction models were integrated with a patient level simulation model of Type 1 diabetes and ‘What If?’ analyses were conducted. The follow-up
intervention was assumed to cost £359 (the cost of repeating the DAFNE intervention) and to provide a 12-month HbA1c reduction of 0.25%, 0.5% or 1.0%. The
integrated model was used to compare provision of a follow-up intervention to DAFNE with current practice. The model estimated costs and quality-adjusted life-years
(QALYs) over a 50-year time horizon from an NHS perspective. Costs and QALYs were discounted at a rate of 3.5%.
Conclusions
The results suggest that providing a follow-up intervention to predicted DAFNE non-
responders may be cost-effective. The results provide a useful starting point for
consideration of the required benefit of a DAFNE follow-up intervention targeted at
HbA1c reduction to demonstrate cost-effectiveness. The adapted economic model offers
the opportunity to investigate research questions about the cost-effectiveness of DAFNE
that could not be assessed using previously published cost-effectiveness models of
Type 1 diabetes.
Results
Initial change in fear of hypoglycaemia5 and initial change in diabetes knowledge6 were
found to be significantly predictive (p<0.05) of 12-month HbA1c change after DAFNE.
The adjusted R2 of prediction model A was 0.064. Prediction model B correctly
categorised 85.2% of non-responders and 50.7% of responders.
The results suggest that providing a follow-up intervention costing £359 to predicted
DAFNE non-responders would be cost-effective at the National Institute for Health and
Clinical Excellence (NICE) threshold of £20,000 per QALY7 if it provided a 12-month
HbA1c reduction of between 0.5% and 1.0%. This result was sensitive to the treatment
response prediction model used, and in some scenarios providing a follow-up
intervention dominated current practice.
References
1. DAFNE Study Group. Training in flexible, intensive insulin management to enable dietary freedom in people with type 1 diabetes: dose
adjustment for normal eating (DAFNE) randomised controlled trial. British Medical Journal 2002;325:746-749.
2. Shearer A, Bagust A, Sanderson D, Heller S, Roberts S. Effectiveness of flexible intensive insulin management to enable dietary freedom in
people with type1 diabetes in the UK. Diabetic Medicine 2004;21:460–467.
3. DAFNE NIHR Research Group. Personal communication: Unpublished data. 2006.
4. Speight J, Amiel S, Bradley C, Heller S, Oliver L, Roberts S, et al. Long-term biomedical and psychosocial outcomes following DAFNE (Dose
Adjustment For Normal Eating) structured education to promote intensive insulin therapy in adults with sub-optimally controlled Type 1
diabetes. Diabetes Research and Clinical Practice 2010;89:22-9.
5. Cox D, Irvine A, Gonder-Frederick L, Nowacek G, Butterfield J. Fear of hypoglycemia: quantification, validation, and utilization. Diabetes Care
1987;10(5):617-21.
6. Fitzgerald J, Funnell M, Hess G, Barr P, Anderson R, Hiss R. The Reliability and Validity of a Brief Diabetes Knowledge Test. Diabetes Care
1998;21(5):706-10.
7. National Institute for Health and Clinical Excellence. Guide to the Methods of Technology Appraisal. 2008.
Acknowledgements
We would like to thank our collaborators Dr Debbie Cooke and Dr Marie Clark at University
College London and Dr Rod Bond at University of Sussex for sharing data and preliminary
research findings from the psychosocial sub-study of the NIHR DAFNE Research
Programme.
Figure 1: The cost-effectiveness of providing a follow-up
intervention costing £359 vs. current practice
* This study was funded by the NIHR. This poster presents independent research commissioned by the NIHR under Improving management of Type 1 diabetes in the UK: the DAFNE programme as a research test-bed. The views expressed in this poster are those of
the authors and not necessarily those of the NHS, the NIHR or the Department of Health.
Prediction model A,
-0.25% HbA1c
benefit
Prediction model A,
-0.5% HbA1c
benefit
Prediction model A,
-1% HbA1c benefit
Prediction model B,
-0.25% HbA1c
benefit
Prediction model B,
-0.5% HbA1c
benefit
Prediction model B,
-1% HbA1c benefit
-£600
-£500
-£400
-£300
-£200
-£100
£0
£100
£200
£300
£400
£500
£600
-0.04 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04
Averagediscountedincrementalcosts
Average discounted incremental QALYs
Prediction
model
Definition of treatment response Statistical analysis method
A Change in HbA1c from baseline to 12-months Multiple linear regression
B Probability of responding to DAFNE (reduction of at least 0.5% by 12 months) Logistic regression