Reader technique as a source of variability in determining malaria parasite density by microscopy
Reader technique as a source of variability in determining malaria parasite density by microscopy
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DOI：
10.1186/1475-2875-5-118
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发表时间：
2006-12-12
期刊：
影响因子：
3
通讯作者：
McKenzie, F. Ellis
中科院分区：
文献类型：
--
作者：
O'Meara, Wendy Prudhomme;Barcus, Mazie;McKenzie, F. Ellis
背景：疟疾寄生虫的准确鉴定和定量是衡量临床试验结果的关键。阳性和阴性诊断通常足以评估治疗结果，但疫苗或预防性药物试验需要测量感染密度作为主要终点。显微镜是最成熟和广泛使用的定量血液中寄生虫密度的技术。方法：对24 - 27名疟疾显微镜专家获得的结果进行了分析，他们独立读取了来自35个供体的895张载玻片，以了解读取器技术如何导致在广泛的密度范围内测量寄生虫密度的差异。结果：35份供体中，平均寄生虫密度的标准差为30% ~ 250%，差异百分比与平均寄生虫密度呈负相关。白细胞计数的数量和寄生虫计数是否在厚膜或薄膜中被证明在显微镜之间有显著的差异。结论：显微镜测量中的错误没有得到广泛的重视或解决，但对疗效试验有严重的后果，包括可能放弃有希望的候选疫苗。
Background: Accurate identification and quantification of malaria parasites are critical for measuring clinical trial outcomes. Positive and negative diagnosis is usually sufficient for the assessment of therapeutic outcome, but vaccine or prophylactic drug trials require measuring density of infection as a primary endpoint. Microscopy is the most established and widely-used technique for quantifying parasite densities in the blood.Methods: Results obtained by 24 - 27 expert malaria microscopists, who had independently read 895 slides from 35 donors, were analysed to understand how reader technique contributes to discrepancy in measurements of parasite density over a wide range of densities.Results: Among these 35 donations, standard deviations ranged from 30% to 250% of the mean parasite density and the percent discrepancy was inversely correlated with the mean parasite density. The number of white blood cells indexed and whether parasites were counted in the thick film or thin film were shown to significantly contribute to discrepancy amongst microscopists.Conclusion: Errors in microscopy measurements are not widely appreciated or addressed but have serious consequences for efficacy trials, including possibly abandoning promising vaccine candidates.