Is the C-reactive protein-to-albumin ratio the most remarkable simple inflammatory marker showing active disease in patients with axial spondyloarthritis, psoriatic arthritis, and rheumatoid arthritis?

objectiveTo learn which of the simple inflammation markers obtained from routine laboratory tests showed active disease best.

methodsThe study included 256 patients (102 patients with axial spondyloarthritis [axSpA], 54 with psoriatic arthritis [PsA], and 100 with rheumatoid arthritis [RA]). The results of the routine laboratory tests requested during the outpatient clinic visits of the patients were noted. Inflammation-related ratio/indices were then calculated from these laboratory tests. Active and inactive diseases were defined according to the disease activity scores for each disease. Logistic regression and receiver operating characteristic (ROC) analyses were performed to determine the best laboratory marker(s) showing active disease and its cutoff value for all three diseases.

resultsC-reactive protein to albumin ratio (CAR) was significantly higher in patients with active axSpA, PsA, and RA diseases than those with inactive diseases (p < 0.001, p = 0.006, and p < 0.001, respectively). In the logistic regression analysis, the CAR was the most important predictor of active disease in patients with axSpA, PsA, and RA. CAR had also showed the active disease at an acceptable level in axSpA and PsA and very well in RA. The cutoff values for active disease in axSpA, PsA, and RA were 0.75, 0.92, and 0.89, respectively.

conclusionCAR may be a promising simple laboratory marker to distinguish active disease in patients with axSpA, PsA, and RA. Key Points • Acute phase reactants and circulating blood cells have become an important target because of the search for a disease activity marker that can be used cheaply and quickly in the daily outpatient routine. • One or more of these simple markers have been previously discussed in various studies with different hypotheses. • We aimed to determine which of the inflammation markers obtained from routine laboratory tests showed active disease and to determine a cutoff value for this/these marker(s). • CAR was the most important simple laboratory marker to distinguish active disease in patients with axSpA, PsA, and RA. In addition, CAR showed the active disease at an acceptable level in axSpA and PsA, and very well in RA.