Department of Immunology and Allergy, Hospital Universitario Reina Sofia, Cordoba, Spain.
GC01 Immunology and Allergy, Maimonides Biomedical Research Institute of Cordoba, Cordoba, Spain.
Lupus Sci Med. 2023 Oct;10(2). doi: 10.1136/lupus-2023-000984.
OBJECTIVE: Antidouble-stranded DNA (dsDNA) antibodies are essential for diagnosis and follow-up of systemic lupus erythematous (SLE). To ensure the best diagnostic approach, most healthcare laboratories opt for a combination of highly sensitive methods, such as solid-phase immunoassays, and highly specific methods, such as the indirect immunofluorescence test (CLIFT). Even so, discordant results are common, thus hindering the diagnostic process. Therefore, this study aimed to characterise a cohort of patients with discrepant results for a dsDNA fluorescence enzyme immunoassay (FEIA) and CLIFT during 2016-2018 and to follow patients up until December 2021. METHODS: We performed an observational, longitudinal and retrospective study on 417 samples from 257 patients who had been referred for suspected connective tissue diseases or followed up after diagnosis. All of them were positive for antinuclear antibodies (ANAs) using an indirect immunofluorescence assay (IFA) on Hep-2 cells, the entry criterion in our laboratory, and positive for FEIA dsDNA. Samples were then tested with CLIFT according to our routine protocol, which includes CLIFT testing after FEIA dsDNA results ≥10 UI/ml. After the assessment of data quality, the final analysis was based on 222 patients. RESULTS: Eighty-three patients (37.4%) had positive results in both tests and met the diagnostic criteria for SLE. However, 139 patients (62.6%) had discrepant results (FEIA+, CLIFT-). Of these, 58 patients (41.7%) had a diagnosis of SLE, with 47 (33.8%) having been previously diagnosed and under treatment. The remaining 11 patients (7.9%) had a new diagnosis of SLE, which was made up within 4 years of the initial screening. A total of 81 of the 139 patients (57.5%) with discrepant results did not meet lupus criteria during the follow-up period. CONCLUSIONS: The study showed that CLIFT could be negative in both treated and newly diagnosed SLE, thus underlining the importance of follow-up of dsDNA-positive results using solid-phase tests. Therefore, quantitative tests such as FEIA could add value to the diagnosis and management of patients with suspected SLE.
目的：抗双链 DNA（dsDNA）抗体是系统性红斑狼疮（SLE）诊断和随访的重要指标。为了确保最佳的诊断方法，大多数医疗保健实验室选择结合高灵敏度方法，如固相免疫测定，以及高特异性方法，如间接免疫荧光试验（CLIFT）。即便如此，仍存在不一致的结果，从而阻碍了诊断过程。因此，本研究旨在描述 2016-2018 年期间 dsDNA 荧光酶免疫分析（FEIA）和 CLIFT 结果不一致的患者队列，并对这些患者进行随访直至 2021 年 12 月。
方法：我们对 257 名疑似结缔组织疾病患者或诊断后随访的患者的 417 份样本进行了观察性、纵向和回顾性研究。所有患者均采用间接免疫荧光法（IFA）在 Hep-2 细胞上检测到抗核抗体（ANA）阳性，这是我们实验室的入组标准，并且 FEIA dsDNA 阳性。然后根据我们的常规方案对样本进行 CLIFT 检测，其中包括在 FEIA dsDNA 结果≥10 UI/ml 后进行 CLIFT 检测。在评估数据质量后，最终分析基于 222 名患者。
结果：83 名患者（37.4%）两种检测均为阳性，并符合 SLE 的诊断标准。然而，139 名患者（62.6%）检测结果不一致（FEIA+，CLIFT-）。其中，58 名患者（41.7%）诊断为 SLE，其中 47 名（33.8%）已被诊断并正在接受治疗。其余 11 名患者（7.9%）新诊断为 SLE，这是在初始筛查后 4 年内做出的诊断。在随访期间，139 名检测结果不一致的患者中有 81 名（57.5%）未符合狼疮标准。
结论：该研究表明，CLIFT 在治疗和新诊断的 SLE 中均可能为阴性，因此强调了使用固相检测对 dsDNA 阳性结果进行随访的重要性。因此，定量检测如 FEIA 可以为疑似 SLE 患者的诊断和管理提供更多价值。
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