Uda H, Ebisu R, Maeda K, Saiki O. Discrepancy Between SAA and CRP levels Linked to the Difference of SAA/CRP ratio in Early Rheumatoid Arthritis.
Mod Rheumatol 2021;
32:1035-1040. [PMID:
34792605 DOI:
10.1093/mr/roab097]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/24/2021] [Accepted: 10/28/2021] [Indexed: 01/05/2023]
Abstract
OBJECTIVES
Indeed, serum amyloid A (SAA) and C-reactive protein (CRP) reportedly seem to have moderate correlation, but discrepancies between CRP and SAA levels have often been reported in patients with early rheumatoid arthritis (ERA). This study aimed to determine the reasons for this discrepancy.
METHODS
ERA patients (n = 206) were enrolled and treated with anti-RA drugs. Clinical features and disease activities were estimated. CRP and SAA levels were monitored, and the SAA/CRP ratio was compared. Correlations between CRP and SAA levels in individuals and between individuals, and disease activity scores were examined.
RESULTS
In a follow-up study, the SAA/CRP ratio remained almost constant over time in the same patients. However, SAA/CRP ratios differed widely between patients (0.233-106.3). In patients with high SAA/CRP ratio (>6.52), many (26.2%) had abnormal SAA values only. In patients with low SAA/CRP ratio (<6.52), not a few (6.8%) exhibited abnormal CRP values only.
CONCLUSIONS
The SAA/CRP ratio remained virtually constant in the same patients but differed dramatically between patients, which clarifies the discrepancy between CRP and SAA levels. CRP is the better marker in low-ratio patients, but not in high-ratio patients; the SAA/CRP ratio is critical for its interpretation.
Collapse