A five-year model to assess the early cost-effectiveness of new diagnostic tests in the early diagnosis of rheumatoid arthritis

Table 2 Five-year cost-effectiveness of new test strategies versus current test strategy

Test strategy	New test	Se^a	Sp^a	Test costs^a	TP n (%)	FP n (%)	TN n (%)	FN n (%)	Costs	QALYs	∆Costs	∆QALYs	ICER	Headroom^b
ACR/EULAR 2010 RA		0.62	0.77	€1,593^d	185 (34)	58 (11)	195 (35)	114 (21)	€16,784	3.430
Add-on all patients	B-cell	0.60	0.90	€150	254 (46)	77 (14)	175 (32)	46 (8)	€16,807	3.454	€23	0.024	€969	€602
	IL-6	0.70	0.53	€50	265 (48)	149 (27)	103 (19)	34 (6)	€17,387	3.451	€603	0.021	€28,171	-€125^e
	MRI	0.90	0.60	€756	288 (52)	135 (24)	117 (21)	11 (2)	€17,848	3.461	€1,063	0.031	€34,318	€312
	Genetic	0.40	0.85	€750	231 (42)	87 (16)	166 (30)	69 (13)	€17,611	3.444	€827	0.014	€57,606	€210
Add-on intermediate-risk patients	B-cell	0.60	0.90	€150	244 (44)	74 (13)	178 (32)	56 (10)	€16,748	3.450	-€37	0.020	Dominant^c	€511
	IL-6	0.70	0.53	€50	254 (46)	135 (24)	117 (21)	46 (8)	€17,271	3.448	€487	0.018	€26,696	-€72^e
	MRI	0.90	0.60	€756	273 (49)	124 (22)	128 (23)	27 (5)	€17,404	3.456	€620	0.026	€23,457	€269
	Genetic	0.40	0.85	€750	224 (41)	82 (15)	170 (31)	75 (14)	€17,211	3.442	€427	0.012	€35,233	€173
Example of what would happen if one would replace the RA classification criteria
Replacement all	B-cell	0.60	0.90	€150	180 (33)	25 (5)	227 (41)	120 (22)	€15,983	3.432	-€801	0.002	Dominant^c	€984
	IL-6	0.70	0.53	€50	210 (38)	119 (22)	134 (24)	90 (16)	€16,849	3.434	€64	0.004	€17,526	€59
	MRI	0.90	0.60	€756	270 (49)	101 (18)	151 (27)	30 (5)	€17,139	3.458	€355	0.027	€12,906	€951
	Genetic	0.40	0.85	€750	120 (22)	38 (7)	214 (39)	180 (33)	€16,675	3.414	€ -110	-0.016	€6,914	€543

Se sensitivity, Sp specificity, TP true positive, FP false positive, TN true negative, FN false negative, QALY quality-adjusted life year, ICER incremental cost-effectiveness ratio (€ per QALY gained), ACR/EULAR American College of Rheumatology/European League Against Rheumatism, RA rheumatoid arthritis, MRI magnetic resonance imaging. ^aThese are the Se, Sp and costs of the new test; the Se and Sp of the combination of the new test plus the ACR/EULAR criteria are reported in the text. ^bWillingness to pay threshold is €20,000 per QALY gained. ^cDominant = better health outcomes and lower costs. ^dCosts of visits and diagnostic tests during first year. ^eMainly due to the low specificity, an IL-6 test as an add-on can never be cost-effective compared to the current test strategy

ISSN: 1478-6362