Cost-effectiveness analysis of bariatric surgery for morbid obesity in Belgium

Figures & data

Figure 1. Structure of the model. Abbreviation. MI, myocardial infarction. Reprinted with permission of Borisenko Oleg from Borisenko et al. Bariatric surgery can lead to net cost savings to health care systems: results from a comprehensive European decision analytic model. Obes Surg 2015;25:1559–68¹².

Table 1. Absolute BMI reduction.

Parameter	Value	Range for one-way sensitivity analysis	Distribution for PSA (SD)	Source
GBP, 1-year, males	12.7	8.7–37.7	Normal (2.2)	SOReg^35 2011
GBP, 2-year, males	12.6	8.6–37.4	Normal (2.2)
SG, 1-year, males	9.7	5.9–25.5	Normal (1.7)
SG, 2-year, males	9.4	5.7–24.7	Normal (1.6)
AGB, 1-year, males	5.6	3.9–16.9	Normal (1.0)
AGB, 2-year, males	6.9	4.8–20.9	Normal (1.2)
GBP, 1-year, females	13.5	9.5–41.1	Normal (2.4)
GBP, 2-year, females	13.5	9.5–41.2	Normal (2.4)
SG, 1-year, females	12.5	7.5–32.8	Normal (2.2)
SG, 2-year, females	14.7	8.9–38.0	Normal (2.6)
AGB, 1-year, females	5.5	3.9–17.0	Normal (0.9)
AGB, 2-year, females	5.1	3.6–15.7	Normal (0.9)

Abbreviations. PSA, probabilistic sensitivity analysis; GBP, gastric bypass; SG, sleeve gastrectomy; AGB, adjustable gastric banding.

Table 2. Cost of bariatric surgery procedures and post-surgery complications (€2,012).

Parameter	Value	Range for one–way sensitivity analysis	Source
Cost of GB without complications	4,433	3,546–5,320	Weighted average value for minor to moderate level of severity APR-DRG 403
Cost of GB with complications	14,577	11,662–17,492	Weighted average value for high to extreme level of severity APR-DRG 403
Cost of SG without complications	4,433	3,546–5,320	Weighted average value for minor to moderate level of severity APR-DRG 403
Cost of SG with complications	14,577	11,662–17,492	Weighted average value for high to extreme level of severity APR-DRG 403
Cost of AGB without complications	4,433	3,546–5,320	Weighted average value for minor to moderate level of severity APR-DRG 403
Cost of AGB with complications	14,577	11,662–17,492	Weighted average value for high to extreme level of severity APR-DRG 403
Cost of removal/revision of AGB without complications	4,433	3,546–5,320	Weighted average value for minor to moderate level of severity APR-DRG 403
Cost of abdominal hernia procedure	2,818	2,254–3,382	APR-DRG 227 value for 2010, updated to 2012
Cost of cholecystectomy	3,103	2,482–3,724	APR-DRG 263 value for 2010, updated to 2012
Cost of leakage and abscess	9,183	7,346–11,020	Weighted average for APR-DRG 222 and APR-DRG 220 value for 2010, updated to 2012
Cost of obstruction	4,211	3,369–5,053	APR-DRG 247 value for 2010, updated to 2012
Cost of stricture	4,211	3,369–5,053	APR-DRG 247 value for 2010, updated to 2012
Cost of gastric ulcer	22	17.6–26.4	An 8-week course of 40 mg omeprazole. Cost was obtained from INAMI^55

Abbreviations. PSA, probabilistic sensitivity analysis; GBP, gastric bypass; SG, sleeve gastrectomy; AGB, adjustable gastric banding; APR-DRG, All Patient Refined Diagnosis-Related Groups; INAMI, Institut National d'Assurance Maladie-Invalidité (National Institute for Health and Disability Insurance).

Table 3. Cost of obesity-related comorbidities and unit costs (€2,012).

Parameter	Value	Range for one-way sensitivity analysis	Distribution for PSA	Source
Cost of T2D	4,418	3,534–5,302	Gamma (α = 100; λ = 44.18)	Jönsson et al.^51 (2002)
Cost of acute stroke	9,248	7,398–11,098	Gamma (α = 100; λ = 92.48)	Annemans et al.^52 (2003)
Cost of post-stroke 1 year	11,253	9,002–13,504	Gamma (α = 100; λ = 112.53)	Annemans et al.^52 (2003)
Cost of post-stroke 2 year	4,454	3,563–5,345	Gamma (α = 100; λ = 44.54)	Annemans et al.^52 (2003), extrapolation based on first 6 months costs
Cost of acute TIA	4,359	3,487–5,231	Gamma (α = 100; λ = 43.59)	APR-DRG 047 value for 2010, updated to 2012
Cost of acute AMI	7,756	6,205–9,307	Gamma (α = 100; λ = 77.56)	Annemans et al.^52 (2003)
Cost of post-MI state	4,842	3,874–5,810	Gamma (α = 100; λ = 48.42)	Annemans et al.^52 (2003)
Cost of HF	2,194	1,755–2,633	Gamma (α = 100; λ = 21.94)	Annemans et al.^53 (1998)
Cost of angina	5,518	4,414–6,622	Gamma (α = 100; λ = 55.18)	Annemans et al.^53 (1998)
Cost of PAD	4,363	3,490–5,236	Gamma (α = 100; λ = 43.63)	Wilson et al.^54 (2012)
Cost of GP visit	15	12–18	—	Nomenclature, INAMI^55
Cost of nurse visit	18	14.4–21.6	—	KCE report, updated to 2012^56
Cost of surgeon visit	31	24.8–37.2	—	Nomenclature, INAMI^55
Cost of endocrinologist visit	56	44.8–67.2	—	Nomenclature, INAMI^55

Abbreviations. PSA, probabilistic sensitivity analysis; T2D, type 2 diabetes; TIA, transient ischemic attack; AMI, acute myocardial infarction; MI, myocardial infarction; HF, heart failure; PAD, peripheral arterial disease; GP, general practitioner; INAMI, Institut National d’Assurance Maladie-Invalidité (National Institute for Health and Disability Insurance); KCE, Federaal Kenniscentrum voor de Gezondheidszorg (The Belgian Health Care Knowledge Centre).

Table 4. Patient baseline characteristics.

Parameter	Value	Range for one-way sensitivity analysis	Distribution for PSA	Source
Age, years	39.2	21–56	Normal (SD =4.5)	Dillemans et al.^34 (2009)
Gender, males (%)	20.69	NA	Beta (α = 1,035; β = 3,965)	Dillemans et al.^34 (2009)
Body mass index, kg/m^2	41.44	23–58	Normal (SD =4.5)	Dillemans et al.^34 (2009)
Diabetes mellitus (%)	9.17	NA	Beta (α = 459; β = 4,542)	Dillemans et al.^34 (2009)
Systolic blood pressure, mmHg	140.1	125–200	Gamma (α = 55.53; λ = 2.52)	Sjöström^40 (2004)
Smoking (%)	20.5	NA	Beta (α = 1,025; β = 3,975)	OECD Factbook^62 (2011)

Abbreviations. PSA, probabilistic sensitivity analysis; OECD, Organization for Economic Co-operation and Development.

Table 5. Base-case results of cost-effectiveness analysis.

	Cost, €	Δ cost, €	LYG, years	Δ LYG	QALY	Δ QALY	ICER, €/QALY
Ten years
CMM arm	6,599	3,788	9.2	0.0	4.5	1.3	2,809
Surgical arm	10,387		9.2		5.8
Lifetime
CMM arm	36,284	–9,332	27.9	1.1	12.9	5.0	Dominates
Surgical arm	26,953		29.0		17.9

Abbreviations. ICER, incremental cost-effectiveness ratio; LYG, life years gained; CMM, conventional medical management; QALY, quality-adjusted life years.

Table 6. Absolute and relative risks of obesity-related comorbidities in the model.

	Angina	MI total non-fatal	MI fatal	Stroke total non-fatal	Stroke fatal	TIA	HF	PAD	Diabetes
Ten years
Absolute risk in the surgical arm	0.02	0.02	0.0004	0.02	0.003	0.002	0.02	0.01	0.04
Absolute risk in the CMM arm	0.02	0.04	0.0006	0.03	0.004	0.003	0.02	0.02	0.15
Relative risk	0.71	0.71	0.66	0.71	0.71	0.71	0.71	0.71	0.27
Lifetime
Absolute risk in the surgical arm	0.11	0.19	0.02	0.17	0.03	0.01	0.13	0.09	0.13
Absolute risk in the CMM arm	0.13	0.24	0.02	0.21	0.04	0.02	0.17	0.11	0.39
Relative risk	0.81	0.78	0.70	0.78	0.78	0.82	0.79	0.82	0.34

Abbreviations. HF, heart failure; MI, myocardial infarction; PAD, peripheral artery disease; TIA, transient ischemic attack; CMM, conventional medical management.

Figure 2. Tornado diagram. One-way sensitivity analysis was produced for a single cohort of 39.2-year non-smoking males with BMI of 41 kg/m². Only variables affecting the results for more than €100 are shown.

Figure 3. Cost-effectiveness acceptability plane. A scatter plot depicting the ICER derived from each iteration of the model from the probabilistic sensitivity analysis.

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