NHS Bowel Cancer Screening Programme Southern Hub, Royal Surrey County Hospital, Guildford, UK.
Berkshire and Surrey Pathology Services, Royal Surrey County Hospital, Guildford, UK.
Clin Chem Lab Med. 2022 Mar 14;60(6):901-906. doi: 10.1515/cclm-2022-0126. Print 2022 May 25.
The National Institute for Health and Care Excellence recommends faecal calprotectin (f-cal) to help differentiate inflammatory bowel diseases from irritable bowel syndrome. Faecal samples for calprotectin have historically been collected at home by patients into screw-top pots and sent to laboratories where calprotectin is extracted and analysed. Faecal haemoglobin (f-Hb) samples are collected at home into specific collection devices containing stabilising buffer. We evaluated the OC-FCa method for f-cal, developed by Eiken Chemical Co., Ltd. (Japan) that uses the same collection device and analyser as f-Hb.
OC-FCa was assessed for limit of blank (LOB), limit of detection (LOD), limit of quantification (LOQ), within and between-run imprecision, linearity, prozone, recovery and carryover. A method comparison against the BÜHLMANN fCAL turbo (BÜHLMANN Laboratories AG, Switzerland) was performed using patient samples and EQA.
The LOB was 3 µg calprotectin/g faeces (µg/g), LOD 8 μg/g and LOQ 20 μg/g. Within and between-run imprecision was <5%; linearity was good (R > 0.99); prozone was appropriately detected; recovery was 99.6%; no observed carryover. OC-FCa showed a strong positive bias compared with BÜHLMANN fCAL turbo (Z=-5.3587, p < 0.001). When categorised using our local pathway, which interprets calprotectin concentrations and need for further investigation, Cohen's Kappa demonstrates substantial agreement at <50 μg/g (κ=0.80) and >150 μg/g (κ=0.63) and fair agreement (κ=0.22) in the borderline category 50-150 μg/g.
The OC-FCa method performed well in the evaluation. With the lack of standardisation for f-cal a clinical study is required to evaluate the positive bias and establish suitable cut-off levels.
英国国家卫生与临床优化研究所建议使用粪便钙卫蛋白（f-cal）来帮助区分炎症性肠病和肠易激综合征。传统上，患者在家中将粪便样本采集到螺旋盖罐中，并将其送到实验室，在实验室中提取和分析钙卫蛋白。粪便血红蛋白（f-Hb）样本则被采集到含有稳定缓冲液的专用采集装置中。我们评估了由日本 Eiken 化学有限公司开发的 OC-FCa 方法，该方法用于 f-cal 的检测，它使用与 f-Hb 相同的采集装置和分析仪。
评估 OC-FCa 的空白限（LOB）、检测限（LOD）、定量限（LOQ）、批内和批间精密度、线性、前区效应、回收率和携带污染。使用患者样本和外部质量评估（EQA）对其与 BÜHLMANN fCAL turbo（瑞士 BÜHLMANN 实验室 AG）的方法进行了比较。
LOB 为 3 µg 钙卫蛋白/g 粪便（µg/g），LOD 为 8 µg/g，LOQ 为 20 µg/g。批内和批间精密度均<5%；线性良好（R>0.99）；前区效应得到适当检测；回收率为 99.6%；未观察到携带污染。OC-FCa 与 BÜHLMANN fCAL turbo 相比显示出强烈的正偏倚（Z=-5.3587，p<0.001）。当使用我们的本地通路对其进行分类，即解释钙卫蛋白浓度和进一步调查的需要时，Cohen's Kappa 在<50 µg/g（κ=0.80）和>150 µg/g（κ=0.63）时显示出较强的一致性，在 50-150 µg/g 的边界类别中显示出适度的一致性（κ=0.22）。
OC-FCa 方法在评估中表现良好。由于 f-cal 缺乏标准化，因此需要进行临床研究来评估其正偏倚并建立合适的截断值。
