Background/Purpose: With technological improvements in genomics, cytomics and metabolomics many promising biomarkers for stratifying individuals at risk of developing Rheumatoid Arthritis will enter the market.  However, research into the potential cost-effectiveness of applying these biomarkers in actual clinical settings has been lacking. This study shows an initial assessment of cost-effectiveness for 4 different technologies (MRI, il6-serum test, RNA B cell signature, genetic assay) applied to intermediate risk patients (3-5 points on the ACR/EULAR criteria for RA) using a one-year time horizon. 

Methods: The cost-effectiveness of the 4 technologies was simulated with a decision model using data from the Rotterdam Early Arthritis Cohort (REACH; prevalence of RA 55%). The comparator was the 2010 ACR/EULAR classification criteria. Test properties (sensitivity, specificity and costs) were based on literature and expert opinion (see table 1). Patients were classified true positive (TP) if they score >=6 points on the criteria or were tested positive and used MTX at 12 months follow-up. True negative (TN) patients were those that scored <6 points, were test negative and did not use MTX at 12 months. Costs included test costs, rheumatology visits and treatment costs. Changes in utilities within 1 year were assigned to TP (+0.1), TN (+0.1), false positive (FP; +0.05) and false negative (FN; -0.05). Outcome assessment included changes in the TP and the FP rate, the diagnostic net reclassification benefit (NB) for intermediate patients, QALYs, costs and ICER. 

Results:

Table 1 shows the results of the new technologies as add-on test to the ACR/EULAR classification strategy. Given the current test properties, the largest net benefit would be achieved by adding RNA B cell signature with an incremental cost effectiveness ratio of €13,939. To stay below a willingness to pay (WTP) threshold of €20,000/QALY gained (given the current assumptions in utilities) the add-on test strategy for intermediate risk patients can cost  €230 at maximum.

Table 1.  Test properties and modeling results for the 4 technologies tested in intermediate patients only

	Se	Sp	Price	Δ TP*	Δ FP*	uNB#	QALY	COSTS	ICER
RA2010	0.65	0.76	–	–	–	–	0.66	€1,084	–
MRI	0.90	0.60	€488	13%	13%	0%	0.67	€1,334	€38,541
B cell	0.60	0.90	€150	9%	3%	45%	0.67	€1,163	€13,939
Il6	0.70	0.53	€100	10%	15%	-37%	0.66	€1,148	€17,343
SNP	0.75	0.85	€1000	11%	5%	37%	0.67	€1,571	€70,347

*Difference in TP or FP rate between ACR/EULAR RA2010 and the new test as a % of the total sample; ^#uNB is the unweighted net benefit ((Δ TP- Δ FP/ diseased intermediate patients)*100%)

Conclusion: When applying new biomarker technologies in patients with intermediate risk of developing RA the largest net benefit would be achieved for RNA B cell signature, a test assigned moderate sensitivity and high specificity. Under the current utility assumptions and a WTP of €20,000/QALY a test strategy would be cost-effective for intermediate risk patients if it costs no more than €230.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/cost-effectiveness-analysis-of-diagnostic-tests-in-the-work-up-of-patients-with-intermediate-risk-of-developing-rheumatoid-arthritis/