Hospital de Clínicas de Porto Alegre, Faculdade de Medicina da Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Serviço de Reumatologia, Hospital de Clínicas de Porto Alegre - HCPA, Faculdade de Medicina da Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2350, Porto Alegre, Rio Grande do Sul, 90035-903, Brazil.
Adv Rheumatol. 2024 May 23;64(1):42. doi: 10.1186/s42358-024-00383-x.
The diagnostic and prognostic relevance of Human Leukocyte Antigen B-27 (HLA-B27) in Axial Spondyloarthritis (AxSpA) is undeniable, with 70% of Ankylosing Spondylitis (AS) patients carrying the B27 gene, contrasted with a mere 4.35% in the general population. Flow cytometry (FC) and Polymerase Chain Reaction (PCR) have emerged as the predominant techniques for routine HLA-B27 typing. While various studies have compared these methods, none have catered to the unique characteristics of the Brazilian demographic. Therefore, this research aims to compare FC and PCR in a Brazilian cohort diagnosed with AxSpA.
An analytical cross-sectional study was undertaken involving 62 AxSpA outpatients from a Brazilian University Hospital. Both FC and PCR-SSP assays were utilized to ascertain HLA-B27 typing. The outcomes (either confirming or refuting the allele's presence) underwent rigorous scrutiny. Agreement between the methodologies was assessed using the kappa statistic. A p-value of < 0.05 was deemed statistically significant.
Of the participants, 90.3% (n = 56) were HLA-B27 positive according to FC, while 79% (n = 49) were identified as positive using the PCR method. FC exhibited a sensitivity rate of 98% paired with a specificity of 38.5%. The Positive Predictive Value for FC stood at 85.7%, and the Negative Predictive Value was 83.5%. Consequently, the overall accuracy of the FC method was gauged at 85.5%. A kappa coefficient of κ = 0.454 was derived.
FC demonstrated noteworthy sensitivity and satisfactory accuracy in HLA-B27 detection, albeit with a reduced specificity when contrasted with PCR-SSP. Nevertheless, given its cost-effectiveness and streamlined operation relative to PCR, FC remains a pragmatic option for preliminary screening in clinical practice, especially in low-income regions. To optimize resource allocation, we advocate for a refined algorithm that initiates by assessing the relevance of HLA-B27 typing based on Choosing Wisely recommendations. It then leans on FC, and, if results are negative yet clinical suspicion persists, advances to PCR. This approach aims to balance diagnostic accuracy and financial prudence, particularly in regions contending with escalating medical costs.
人类白细胞抗原 B-27（HLA-B27）在轴性脊柱关节炎（AxSpA）中的诊断和预后相关性是不可否认的，70%的强直性脊柱炎（AS）患者携带 B27 基因，而普通人群中仅有 4.35%。流式细胞术（FC）和聚合酶链反应（PCR）已成为常规 HLA-B27 分型的主要技术。虽然已有多项研究比较了这些方法，但没有一项研究针对巴西人群的特点。因此，本研究旨在比较 FC 和 PCR 在巴西 AxSpA 患者队列中的应用。
本研究为分析性横断面研究，纳入了巴西某大学医院的 62 名 AxSpA 门诊患者。均采用 FC 和 PCR-SSP 方法检测 HLA-B27 分型。对结果（确认或否定等位基因的存在）进行严格审查。采用 Kappa 统计评估两种方法的一致性。p 值<0.05 为统计学显著。
根据 FC，62 名参与者中有 90.3%（n=56）为 HLA-B27 阳性，而 79%（n=49）用 PCR 方法确定为阳性。FC 的灵敏度为 98%，特异性为 38.5%。FC 的阳性预测值为 85.7%，阴性预测值为 83.5%。因此，FC 方法的总体准确性为 85.5%。得到 Kappa 系数κ=0.454。
FC 在 HLA-B27 检测中具有较高的灵敏度和令人满意的准确性，但其特异性低于 PCR-SSP。然而，由于其成本效益和操作简便性优于 PCR，FC 仍然是临床实践中初步筛查的实用选择，尤其是在低收入地区。为了优化资源分配，我们提倡根据明智选择建议评估 HLA-B27 分型的相关性，然后采用 FC，如果结果为阴性但临床怀疑仍然存在，则进行 PCR。这种方法旨在平衡诊断准确性和财务谨慎性，特别是在面临医疗成本不断上升的地区。
