Budhram Adrian, Rotstein Dalia L, Yang Liju, Yeh E Ann
London Health Sciences Centre, Department of Clinical Neurological Sciences, Western University, London, ON, Canada.
London Health Sciences Centre, Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada.
Front Neurol. 2024 Mar 14;15:1380541. doi: 10.3389/fneur.2024.1380541. eCollection 2024.
In January 2023, our laboratory began performing serum myelin oligodendrocyte glycoprotein antibody (anti-MOG) titers by fixed cell-based assay (CBA). As a quality assurance (QA) assessment, we evaluated titer positive predictive value (PPV) as well as impact of sample collection timing on titers.
Among patients who underwent antibody titers to distinguish between low-positive (<1:100) and clear-positive (≥1:100) anti-MOG, records were reviewed to classify results as true-positive (TP) or false-positive (FP) and facilitate PPV calculation. Timing of sample collection relative to administration of immunotherapy and symptom onset was determined for TP results.
Overall PPV of anti-MOG was 70/85 (82%). The PPV of low-positive anti-MOG was significantly lower than clear-positive anti-MOG (72% vs. 95%, = 0.009). The difference in PPV between low-positive and clear-positive anti-MOG was significant among adults tested, but not children. Among patients with TP anti-MOG, the proportion who received immunotherapy prior to sample collection was significantly higher and median time from symptom onset to sample collection was significantly longer for low-positive compared to clear-positive results.
Overall PPV of anti-MOG testing by fixed CBA was reasonably high. The PPV of low-positive anti-MOG was significantly lower than clear-positive anti-MOG. This was driven by the significantly lower PPV of low-positive anti-MOG in adults, possibly reflecting the lower prevalence of MOG antibody-associated disease among adults tested. Timing of sample collection relative to administration of immunotherapy and symptom onset may substantially impact titers, indicating that testing should ideally be performed prior to immunotherapy and close to time of attack.
2023年1月，我们实验室开始通过固定细胞检测法（CBA）检测血清髓鞘少突胶质细胞糖蛋白抗体（抗MOG）滴度。作为质量保证（QA）评估，我们评估了滴度阳性预测值（PPV）以及样本采集时间对滴度的影响。
在接受抗体滴度检测以区分低阳性（<1:100）和明确阳性（≥1:100）抗MOG的患者中，回顾记录以将结果分类为真阳性（TP）或假阳性（FP），并便于计算PPV。对于TP结果，确定样本采集时间相对于免疫治疗给药和症状发作的时间。
抗MOG的总体PPV为70/85（82%）。低阳性抗MOG的PPV显著低于明确阳性抗MOG（72%对95%，P = 0.009）。在接受检测的成年人中，低阳性和明确阳性抗MOG之间的PPV差异显著，但儿童中不显著。在抗MOG为TP的患者中，与明确阳性结果相比，低阳性结果患者在样本采集前接受免疫治疗的比例显著更高，且从症状发作到样本采集的中位时间显著更长。
通过固定CBA进行抗MOG检测的总体PPV相当高。低阳性抗MOG的PPV显著低于明确阳性抗MOG。这是由成年人中低阳性抗MOG的PPV显著较低所驱动的，这可能反映了在接受检测的成年人中MOG抗体相关疾病的患病率较低。样本采集时间相对于免疫治疗给药和症状发作的时间可能会对滴度产生重大影响，这表明理想情况下检测应在免疫治疗之前且接近发作时间进行。
