Alonso-Castro Sara, González Del Pozo Pablo, Alvarez Paula, Calleja Norma, Burger Stefanie, Queiro Rubén
Rheumatology Division, Oviedo University School of Medicine, Oviedo, Spain.
Rheumatology Division, and Department of Medicine, Oviedo University School of Medicine, and Translational Immunology Division, Biohealth Research Institute of the Principality of Asturias (ISPA), Oviedo, Spain.
Clin Exp Rheumatol. 2025 Mar;43(3):472-476. doi: 10.55563/clinexprheumatol/lelu7p. Epub 2025 Feb 5.
Although C-reactive protein (CRP) is the main inflammatory biomarker used for axial spondyloarthritis (axSpA) assessment, its sensitivity for detecting active disease is low. We aimed to analyse CRP thresholds capable of discriminating across disease activity states in axSpA.
Two hundred consecutive patients with axSpA were recruited (with/without biologics). Discriminative CRP thresholds were determined by the Youden index, while their sensitivity/specificity was evaluated by the area under the ROC curve (AUROC). Sensitivity analyses were performed based on exposure to biologic drugs.
One hundred and twenty-two men and 78 women were included, mean age 43.5±11.6 years, mean age at diagnosis 34±10.7 years, average disease duration 8.6±6.5 years. Median CRP 0.20 mg/dl (IQR 0.10-0.40). A CRP ≥0.25 mg/dl discriminated the population with high/very high disease activity [AUROC 0.71; OR 3.9, p<0.001]. This threshold rose to CRP ≥0.35 mg/dl [AUROC 0.72; OR 10.4, p<0.001] among patients without biological therapy, remaining at ≥0.25 mg/dl [AUROC 0.70; OR 4.02, p<0.001] in those exposed to these therapies. The standard inflammatory CRP value (≥0.5 mg/dl) was highly specific (0.90) but poorly sensitive (0.35) in detecting high/very high disease activity states, making it less discriminatory than previous thresholds.
Our results suggest adopting lower than standard CRP cut-off values for a better assessment of both the global activity of the disease and a better interpretation of the composite activity indices used in axSpA.
尽管C反应蛋白（CRP）是用于评估中轴型脊柱关节炎（axSpA）的主要炎症生物标志物，但其检测疾病活动的敏感性较低。我们旨在分析能够区分axSpA不同疾病活动状态的CRP阈值。
连续招募了200例axSpA患者（使用/未使用生物制剂）。通过约登指数确定具有鉴别性的CRP阈值，同时通过ROC曲线下面积（AUROC）评估其敏感性/特异性。基于生物制剂的使用情况进行敏感性分析。
纳入122名男性和78名女性，平均年龄43.5±11.6岁，诊断时平均年龄34±10.7岁，平均病程8.6±6.5年。CRP中位数为0.20mg/dl（四分位间距0.10 - 0.40）。CRP≥0.25mg/dl可区分疾病活动度高/非常高的人群[AUROC 0.71；OR 3.9，p<0.001]。在未接受生物治疗的患者中，该阈值升至CRP≥0.35mg/dl[AUROC 0.72；OR 10.4，p<0.001]，而在接受这些治疗的患者中保持在≥0.25mg/dl[AUROC 0.70；OR 4.02，p<0.001]。标准炎症CRP值（≥0.5mg/dl）在检测疾病活动度高/非常高的状态时具有高度特异性（0.90）但敏感性较差（0.35），使其鉴别能力低于先前的阈值。
我们的结果表明，采用低于标准的CRP临界值，能更好地评估疾病的整体活动情况，并更好地解读axSpA中使用的综合活动指数。
