Kumar Abhishek, Vasdev Vivek, Patnaik Saroj Kumar, Bhatt Satyam, Singh Ramakant, Bhayana Aprajita, Hegde Arun, Kumar Ashwani
Classified Specialist (Medicine) & Rheumatologist, Command Hospital (Eastern Command), Kolkata, India.
Professor & Head, Department of Geriatrics Medicine, Armed Forces Medical College, Pune, India.
Med J Armed Forces India. 2022 Sep;78(Suppl 1):S69-S74. doi: 10.1016/j.mjafi.2020.04.007. Epub 2020 Jul 17.
There is lack of Indian data on diagnostic utility of rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) for diagnosis of rheumatoid arthritis (RA) and prevalence of these antibodies in patients with RA and the healthy population. The study was aimed to assess the diagnostic utility and prevalence of RF and ACPA at different titers in the Indian scenario.
All the patients of RA fulfilling the European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) 2010 classification criteria and age and gender-matched healthy controls were included in the study. RF and ACPA were measured by nephelometry and the enzyme-linked immunosorbent assay (ELISA) method, respectively.
Of 803 patients (291 men and 512 women) included, the RF was positive in 566 (70.5%) study patients. The ACPA was positive in 527 (71.7%) patients of 735 of them. Among 408 healthy controls, 45 (11%) were RF positive and 19 (4.7%) were ACPA positive.At the positive cutoff level, the RF had a specificity of 87.6% (95% confidence interval [CI] = 84.4-90.8; positive likelihood ratio [LR+] 5.7). Specificity at 2 and 3 times above the upper limit of normal (ULN) increased to 96.2% (95% CI = 94.3-98.1; LR+ 15.7) and 97.1% (95% CI = 95.5-98.7; LR+ 17.1), respectively.The specificity of ACPA at the positive cutoff level was 94.4% (95% CI = 92.2-96.6; LR+ 12.7), which increased to 98% (95% CI = 96.6-99.4), at 2xULN level. The likelihood ratio for ACPA at all cutoff levels measured was more than 10.
The sensitivity and specificity of RF and ACPA in our study population are comparable with those of other studies. ACPA at lower titers may have sufficient diagnostic utility for RA in an appropriate clinical setting.
在印度，缺乏关于类风湿因子（RF）和抗瓜氨酸化蛋白抗体（ACPA）对类风湿关节炎（RA）的诊断效用以及这些抗体在RA患者和健康人群中的患病率的数据。本研究旨在评估在印度情况下不同滴度的RF和ACPA的诊断效用及患病率。
本研究纳入了所有符合2010年欧洲抗风湿病联盟/美国风湿病学会（EULAR/ACR）分类标准的RA患者以及年龄和性别匹配的健康对照。分别采用散射比浊法和酶联免疫吸附测定（ELISA）法检测RF和ACPA。
在纳入的803例患者（291例男性和512例女性）中，566例（70.5%）研究患者的RF呈阳性。在735例患者中，527例（71.7%）的ACPA呈阳性。在408例健康对照中，45例（11%）RF呈阳性，19例（4.7%）ACPA呈阳性。在阳性临界值水平，RF的特异性为87.6%（95%置信区间[CI]=84.4 - 90.8；阳性似然比[LR+]5.7）。高于正常上限（ULN）2倍和3倍时的特异性分别增至96.2%（95%CI = 94.3 - 98.1；LR+15.7）和97.1%（95%CI = 95.5 - 98.7；LR+17.1）。ACPA在阳性临界值水平的特异性为94.4%（95%CI = 92.2 - 96.6；LR+12.7），在2倍ULN水平时增至98%（95%CI = 96.6 - 99.4）。所测所有临界值水平下ACPA的似然比均大于10。
我们研究人群中RF和ACPA的敏感性和特异性与其他研究相当。在适当的临床环境中，较低滴度的ACPA对RA可能具有足够的诊断效用。
