Session Information
Title: Rheumatoid Arthritis - Clinical Aspects: Novel Biomarkers and Other Measurements of Disease Activity
Session Type: Abstract Submissions (ACR)
Background/Purpose:
To assess the sensitivity, specificity, and predictive values of rheumatoid factor (RF) as a test for rheumatoid arthritis (RA) in primary care, and to estimate the costs associated with the use of RF in primary care settings
Methods:
Design: a retrospective cohort study using electronic data from the Information System for the Development of Research in Primary Care (SIDIAP database), which contains the complete primary care records and laboratory results of more than 5 million people (over 80% of the population) in Catalonia, Spain.
Setting: primary care
Participants: patients aged 18 or above registered in the SIDIAP database with at least one RF test performed between 01/01/2006 and 31/12/2011, excluding those who had a diagnosis of RA at the start of the study period.
Outcome measures: RA diagnosis (as coded in medical records) within the first year after RF testing, and cost of RF testing per case of RA.
Results:
495,434 patients out of an eligible 4,796,498 (10.3%) people were tested for RF at least once during the study period. 107,362 (21.7%) were sero-positive of which 2,768 (2.6%) of these were diagnosed with RA in the following year. Similarly, 1,141/388,072 (0.3%) sero-negative participants were subsequently diagnosed with RA. RF testing had a sensitivity of 70.8% (95% CI 69.4 to 72.2), specificity 78.7% (78.6 to 78.8), and positive and negative predictive values of 2.6% (2.5 to 2.7) and 99.7% (99.6 to 99.7) respectively. An estimated €3,963,472 was spent on RF testing in the duration of the study, with a cost of €1,432 per true positive case.
Conclusion:
The low prevalence of RA in this primary care population resulted in a very high cost of testing for every case of RA diagnosed. Limiting RF testing to patients with a higher pre-test probability would significantly reduce the overall cost of testing.
Disclosure:
R. Luqmani,
GSK,
5,
Roche Pharmaceuticals,
5,
Janssen Pharmaceutica Product, L.P.,
5,
Nordic Bioscience Diagnostic,
5,
Chemocentryx,
5,
UCB,
5;
K. Morsley,
None;
A. Miller,
None;
C. J. Edwards,
None;
M. K. Javaid,
None;
D. Prieto-Alhambra,
Bioiberica,
2,
Amgen Spain,
2;
R. Pinedo-Villanueva,
None;
M. Medina Peralta,
None;
S. Calero Munoz,
None;
N. Arden,
FLEXION pharmanet,
5,
Lily,
5,
Merck Pharmaceuticals,
5,
Q-Med,
5,
Roche Pharmaceuticals,
5,
Smith & Nephew, Inc.,
5,
Novartis Pharmaceutical Corporation,
2,
Pfizer Inc,
2;
F. Fina-Aviles,
None;
C. Cooper,
Amgen,
5,
GSK,
5,
Alliance for Better Bone Health, The ALR,
5,
MSD,
5,
Eli Lilly and Company,
5,
Pfizer Inc,
5,
Novartis Pharmaceutical Corporation,
5,
Servier,
5,
Merck Human Health,
5,
Medtronic,
5,
Roche Pharmaceuticals,
5.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/diagnostic-accuracy-and-associated-costs-of-rheumatoid-factor-testing-in-primary-care-a-population-based-cohort-study-in-spain/