Objective: To investigate the diagnostic value of anti-Sa antibody and anti-carbonylated protein (CarP) antibody for rheumatoid arthritis (RA). Methods: A retrospective selection of 180 patients with RA who came to Qinghai Provincial People's Hospital from September 2022 to February 2023. Grouped according to the Disease Activity Score of 28 joints (DAS28), 101 of them were patients with RA in high activity (RAH group), 24 males and 77 females, aged 18-79 (53.2±12.2), and 79 patients with RA in low activity (RAL group), 23 males and 56 females, aged 24-78 (49.0±12.9).A total of 90 patients with other autoimmune diseases in the hospital in the same period were choosed as the other immune disease group, and 90 healthy physical examiners were as the healthy control group. The levels of serum anti-Sa and anti-CarP antibodies were measured by ELISA, RF by immunoscattering turbidimetry, anti-CCP by chemiluminescence, and ESR by Weil's method in four groups of patients. The area under the subject operating characteristic (ROC) curve (AUC) was applied to assess the sensitivity and specificity of each index alone or in combination for the diagnosis of RA. Results: In the RAH group, RAL group, other immune disease group, and healthy control group, the RF levels were 117.6 (61.0, 161.1), 92.7 (48.1, 92.7), 10.1 (5.3, 24.6), and 8.1 (6.0, 12.8) U/ml, anti-CCP antibody levels were 202.7 (67.1, 594.4), 212.9 (98.3, 416.2), 9.4 (6.6, 11.8), 1.9 (0.8, 4.9) U/ml, anti-Sa antibody levels were 305.3 (120.4, 614.9), 235.8 (161.6, 336.9), 123.9 (41.8, 240.5), 165.1 (71.1, 237.5) U/ml, and anti-CarP antibody levels were 11.7 (7.9, 21.6), 5.2 (3.3, 7.7), 5.1 (3.9, 6.5), and 5.8 (3.8, 7.5) mg/L, respectively, and their differences were statistically significant (all P<0.001). The level of anti-CarP antibody was higher in the RAH group than in the RAL group (P<0.001), and the difference in anti-Sa antibody was not statistically significant (P>0.05). The critical value of anti-Sa antibody at 181.45 μg/L showed a sensitivity of 67.2%, specificity of 65.6% and AUC of 0.710 (95%CI: 0.645-0.775); The sensitivity was 52.8% and the specificity was 88.9% with an AUC of 0.706 (95%CI: 0.646-0.766) at a critical value of 7.98 U/ml for the anti-CarP antibody. The AUC for the combined RF, anti-CCP antibody and anti-CarP antibody assay was 0.986 (95%CI: 0.977-0.996). Conclusion: Anti-CarP antibody is clinically significant in distinguishing active RA. RF, anti-CCP, and anti-CarP antibodies can be detected together with high AUC results, suggesting the potential for developing an improved method for diagnosing RA.
目的： 探讨抗Sa抗体和抗氨甲酰化蛋白（CarP）抗体对类风湿性关节炎（RA）的诊断价值。 方法： 回顾性选取2022年9月至2023年2月青海省人民医院180例RA患者，根据28关节疾病活动度评分（DAS28），其中101例为RA高活动期患者（RAH组），男24例，女77例，年龄18~79（53.2±12.2）岁；79例为RA低活动期患者（RAL组），男23例，女56例，年龄24~78（49.0±12.9）岁；选取同期本院90例其他自身免疫性疾病患者为其他免疫病组，同期90名健康体检者为健康对照组。采用ELISA法测定4组患者血清抗Sa抗体和抗CarP抗体的水平，采用免疫散射比浊法测定类风湿因子（RF）水平，采用化学发光法检测抗环瓜氨酸肽（CCP）抗体水平；应用受试者工作特征（ROC）曲线下面积（AUC）评估各指标单独或者联合检测诊断RA的灵敏度、特异度。 结果： RAH组、RAL组、其他免疫病组、健康对照组RF水平分别为117.6（61.0，161.1）、92.7（48.1，92.7）、10.1（5.3，24.6）、8.1（6.0，12.8）U/ml，抗CCP抗体水平分别为202.7（67.1，594.4）、212.9（98.3，416.2）、9.4（6.6，11.8）、1.9（0.8，4.9）U/ml，抗Sa抗体水平分别为305.3（120.4，614.9）、235.8（161.6，336.9）、123.9（41.8，240.5）、165.1（71.1，237.5）U/ml，抗CarP抗体水平分别为11.7（7.9，21.6）、5.2（3.3，7.7）、5.1（3.9，6.5）、5.8（3.8，7.5）mg/L，差异均有统计学意义（均P<0.001）；RAH组抗CarP抗体水平高于RAL组（P<0.001），抗Sa抗体差异无统计学意义（P>0.05）。抗Sa抗体的临界值为181.45 μg/L时，灵敏度为67.2%，特异度为65.6%，AUC为0.710（95%CI：0.645~0.775）；抗CarP抗体的临界值为7.98 U/ml时，灵敏度为52.8%，特异度为88.9%，AUC为0.706（95%CI：0.646~0.766）。RF、抗CCP抗体与抗CarP抗体联合检测的AUC为0.986（95%CI：0.977~0.996）。 结论： 抗CarP抗体对鉴别RA活动期具有较好的临床意义。RF、抗CCP抗体和抗CarP抗体联合检测AUC较高，有望成为诊断RA的新组合。.