Abstract：
BACKGROUND: Anti-nuclear antibody (ANA) testing is among the most common immunological test requested in the diagnostic immunology laboratory. The main purpose of this test is to screen for the underlying systemic autoimmune rheumatic diseases (SARDs). The gold standard laboratory method for ANA detection is by the indirect immunofluorescence (IIF) assay. In most laboratories, positive ANA-IIF is reported in terms of titration and pattern.
OBJECTIVE: This study was conducted with the aim of determining the correlation between ANA-IIF titration and pattern for the diagnosis of SARDs.
METHODS: A retrospective study was conducted whereby the positive ANA-IIF samples from 1st July 2018 until 31st December 2019 and 1st January 2021 until 31st March 2021 were included in this study. The duplicate samples were excluded. ANA-IIF titration and pattern were recorded for all patients. The demographic, clinical, and final diagnosis data were retrieved from each patient\'s clinical note.
RESULTS: A total of 179 patients were included for analysis. The majority of the patients were female (79.9%) and from Malay ethnicity (66.5%). Sixty-five patients (36.3%) had ANA-IIF positive at 1:80 titration followed by 45 patients (25.1%) positive at titration of equal or more than 1:160. Speckled was the predominant pattern visualised in 90 patients (50.3%) followed by homogeneous in 76 patients (42.5%). Forty-five patients (25.1%) were finally diagnosed with SARDs with 41 of them diagnosed as SLE. ANA titration was significantly associated with the final diagnosis of SARDs at all titres (p<0.001) but the best cut-off was noted at a titre of equal or more than 1:320 with the sensitivity and specificity of 86.7% and 77.6% respectively. The homogeneous pattern was also significantly associated with SARDs (p=0.04). The final diagnosis of SARDs were significantly higher in female (p=0.03) and their age was significantly younger (p<0.001).
CONCLUSIONS: ANA-IIF titration of equal or more than 1:320 can be used as the best titration for differentiating between SARDs and non-SARDs in a positive ANA sample. Patients with homogeneous pattern were more likely to be diagnosed with SARDs than other ANA-IIF patterns.
OBJECTIVE: This study was conducted with the aim of determining the correlation between ANA-IIF titration and pattern for the diagnosis of SARDs.
METHODS: A retrospective study was conducted whereby the positive ANA-IIF samples from 1st July 2018 until 31st December 2019 and 1st January 2021 until 31st March 2021 were included in this study. The duplicate samples were excluded. ANA-IIF titration and pattern were recorded for all patients. The demographic, clinical, and final diagnosis data were retrieved from each patient\'s clinical note.
RESULTS: A total of 179 patients were included for analysis. The majority of the patients were female (79.9%) and from Malay ethnicity (66.5%). Sixty-five patients (36.3%) had ANA-IIF positive at 1:80 titration followed by 45 patients (25.1%) positive at titration of equal or more than 1:160. Speckled was the predominant pattern visualised in 90 patients (50.3%) followed by homogeneous in 76 patients (42.5%). Forty-five patients (25.1%) were finally diagnosed with SARDs with 41 of them diagnosed as SLE. ANA titration was significantly associated with the final diagnosis of SARDs at all titres (p<0.001) but the best cut-off was noted at a titre of equal or more than 1:320 with the sensitivity and specificity of 86.7% and 77.6% respectively. The homogeneous pattern was also significantly associated with SARDs (p=0.04). The final diagnosis of SARDs were significantly higher in female (p=0.03) and their age was significantly younger (p<0.001).
CONCLUSIONS: ANA-IIF titration of equal or more than 1:320 can be used as the best titration for differentiating between SARDs and non-SARDs in a positive ANA sample. Patients with homogeneous pattern were more likely to be diagnosed with SARDs than other ANA-IIF patterns.
摘要：
背景：抗核抗体（ANA）测试是诊断免疫学实验室要求的最常见的免疫学测试之一。该测试的主要目的是筛选潜在的全身性自身免疫性风湿性疾病（SARD）。用于ANA检测的金标准实验室方法是通过间接免疫荧光(IIF)测定。在大多数实验室里,阳性ANA-IIF以滴定和模式报告。
目的：本研究旨在确定ANA-IIF滴定与SARDs诊断模式之间的相关性。
方法：进行了一项回顾性研究，将2018年7月1日至2019年12月31日以及2021年1月1日至2021年3月31日的ANA-IIF阳性样本纳入本研究。排除重复样品。记录所有患者的ANA-IIF滴定和模式。人口统计，临床,并从每位患者的临床记录中检索最终诊断数据.
结果：共纳入179例患者进行分析。大多数患者为女性（79.9％）和马来人（66.5％）。65名患者（36.3％）的ANA-IIF在1：80滴定时呈阳性，其次是45名患者（25.1％）的滴定等于或大于1：160。斑点是90例患者（50.3％）的主要视觉模式，其次是76例患者（42.5％）的均匀模式。45例(25.1%)最终诊断为SARDs，其中41例诊断为SLE。ANA滴定在所有滴度下与SARDs的最终诊断显着相关（p<0.001），但在滴度等于或大于1：320时注意到最佳截止值，灵敏度和特异性分别为86.7％和77.6％。同质模式也与SARD显著相关(p=0.04)。SARDs的最终诊断明显高于女性（p=0.03），年龄明显较年轻（p<0.001）。
结论：ANA-IIF滴定等于或大于1:320可用作区分阳性ANA样品中SARDs和非SARDs的最佳滴定。与其他ANA-IIF模式相比，具有同质模式的患者更有可能被诊断为SARD。
目的：本研究旨在确定ANA-IIF滴定与SARDs诊断模式之间的相关性。
方法：进行了一项回顾性研究，将2018年7月1日至2019年12月31日以及2021年1月1日至2021年3月31日的ANA-IIF阳性样本纳入本研究。排除重复样品。记录所有患者的ANA-IIF滴定和模式。人口统计，临床,并从每位患者的临床记录中检索最终诊断数据.
结果：共纳入179例患者进行分析。大多数患者为女性（79.9％）和马来人（66.5％）。65名患者（36.3％）的ANA-IIF在1：80滴定时呈阳性，其次是45名患者（25.1％）的滴定等于或大于1：160。斑点是90例患者（50.3％）的主要视觉模式，其次是76例患者（42.5％）的均匀模式。45例(25.1%)最终诊断为SARDs，其中41例诊断为SLE。ANA滴定在所有滴度下与SARDs的最终诊断显着相关（p<0.001），但在滴度等于或大于1：320时注意到最佳截止值，灵敏度和特异性分别为86.7％和77.6％。同质模式也与SARD显著相关(p=0.04)。SARDs的最终诊断明显高于女性（p=0.03），年龄明显较年轻（p<0.001）。
结论：ANA-IIF滴定等于或大于1:320可用作区分阳性ANA样品中SARDs和非SARDs的最佳滴定。与其他ANA-IIF模式相比，具有同质模式的患者更有可能被诊断为SARD。
