Cost-effectiveness of dapagliflozin versus DPP-4 inhibitors as an add-on to Metformin in the Treatment of Type 2 Diabetes Mellitus from a UK Healthcare System Perspective

Charokopou, M.; McEwan, P.; Lister, S.; Callan, L.; Bergenheim, K.; Tolley, K.; Postema, R.; Townsend, R.; Roudaut, M.

doi:10.1186/s12913-015-1139-y

Table 1 Summary of model inputs: baseline characteristics and treatment effects

From: Cost-effectiveness of dapagliflozin versus DPP-4 inhibitors as an add-on to Metformin in the Treatment of Type 2 Diabetes Mellitus from a UK Healthcare System Perspective

Baseline characteristic		Baseline value
Age (years)		57.51
Proportion female (%)		47.00
Duration of diabetes (years)		6.01
Height (m)		1.69
Proportion Afro-Caribbean (%)		6.20^b
Proportion smokers		36.90
HbA1c^a (%)		8.05
Weight (kg)		87.84
SBP (mmHg)		133.30
TC (mg/dL)		199.57
HDL-C (mg/dL)		44.09
Treatment effect	DAPA + MET	DPP-4i + MET	Insulin + MET^g	Intensified insulin^c
∆HbA1c^c (%)	−0.69	−0.61	−1.10	−1.11
∆Weight^c (kg)	−3.36	−0.61	+1.08	+1.90^h
∆SBP^c (mmHG)	0^d	0^d	0^d	0^d
∆TC^c (mg/dL)	0^d	0^d	0^d	0^d
∆HDL-C^c (mg/dL)	0^d	0^d	0^d	0^d
Probability of Discontinuation^e	0.081	0.043	0^d	0^d
Probability. of hypoglycaemic events (symptomatic)^f	0.031	0.046	0.011	0.616
Probability of hypoglycaemia (severe)^f	0.0004	0.001	0.037	0.022
Probability of urinary tract infection^f	0.074	0.054	0^d	0^d
Probability of genital infection^f	0.123	0^d	0^d	0^d
Event	Utility decrement		Source
Diabetes-related complications
Ischaemic heart disease	0.090		Clarke, 2003 [23]
Myocardial infarction	0.550		Clarke, 2003 [23]
Congestive heart failure	0.108		Clarke, 2003 [23]
Stroke	0.164		Clarke, 2003 [23]
Amputation	0.280		Clarke, 2003 [23]
Blindness	0.074		Clarke, 2003 [23]
End-stage renal disease	0.263		Currie, 2005 [24]
Hypoglycaemia
Symptomatic	0.042		Currie, 2006 [39]
Nocturnal	0.008		Currie, 2006 [39]
Severe	0.047		Currie, 2006 [39]
Adverse events
Urinary tract infection (UTI)	0.00283		Barry, 1997 [25]
Genital infection	0.00283		Assumed to be the same as UTI
BMI changes
Per unit increase	0.0472		Lane, 2012 [26]
Per unit decrease	+0.0171		Lane, 2012 [26]
Drug acquisition cost	Price per tabletⁱ	Dose per tablet/pen	Daily dose	Annual cost (£)
Dapagliflozin	£1.31	10 mg	10 mg	£476.92
DPP-4i (sitagliptin^j)	£1.19	100 mg	100 mg	£433.57
Metformin	£0.02	500 mg	2000 mg	£23.46
Insulin^k (Insuman® Basal)	£0.47/day	300 IU	40 IU	£170.23
Intensified insulin	£0.70/day	300 IU	60 IU	£256.96
Diabetes-related complication cost^l	Fatal	Non-Fatal	Maintenance	Source
Ischaemic heart disease	-	£3,479	£1,149	Clarke, 2003 [21]
Myocardial infarction	£2,244	£6,709	£1,105	Clarke, 2003 [21]
Congestive heart failure	£3,880	£3,880	£1,360	Clarke, 2003 [21]
Stroke	£5,658	£4,103	£776	Clarke, 2003 [21]
Amputation	£13,359	£13,359	£771	Clarke, 2003 [21]
Blindness	-	£1,752	£742	Clarke, 2003 [21]
End-stage renal disease	-	£34,806	£34,806	Baboolal, 2008 [40]
Adverse event, renal monitoring and discontinuation costs		Cost input	Source
Severe hypoglycaemic event		£390	Hammer, 2009 [41]
Renal monitoring		£38.67	Assumed to incur one GP visit cost and a 24-hour creatine clearance determination [42, 43]
Urinary tract infection, genital infection		£36	Assumed to incur one GP visit cost [42]
Discontinuation		£36	Assumed to incur one GP visit cost [42]

^aValue was applied as the HbA1c switching threshold; it was considered to be a representative threshold value in real-world UK clinical practice as it was the average baseline HbA1c value of patients entering the phase 3 clinical trials that were included in the indirect comparison before switching to dual oral therapy
^bValue sourced from randomised controlled trial by Nauck et al., 2010 [19]
∆ Mean change from baseline
^c Effects apply to the first year after treatment initiation
^d No estimate available and/or zero value assumed
^eProbability of discontinuation was applied during the first model cycle
^fProbabilities of adverse events were applied during every model cycle
^gMonami, 2008 [44]
^‡‡NICE HTA report Chapter 4 [45]
^hWeight change from Montanana, 2008 [46]. Chosen as most recent study reporting weight effect included in the NICE HTA report
ⁱThe daily costs are based on pack costs and have been rounded. The source of the unit costs are England and Wales Drug Tariff costs, February 2012. These costs are in general consistent with BNF63 drug prices
^jSitagliptin is the most frequently prescribed DPP-4i in the UK (80 % of DPP-4i market as of December 2011, data on file)
^kThe cost of insulin was based on a patient baseline weight of 88 kg, which if it remained stable would equate to an annual cost of £170.23 (and £256.96 for intensified insulin). However, in the model, weight changed over time, hence the actual annual cost of insulin (with dosage according to weight) in the economic analysis varies according to the simulated change in weight. Insulin daily cost per kg = £0.0053, insulin intensified daily cost per kg = £0.008
^lPrices were indexed to 2011 using the Hospital and Community Health Services Pay & Prices index
Abbreviations: HbA1c, Glycated haemoglobin; SBP, systolic blood pressure; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; ∆, absolute change from baseline; GP, general practitioner

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