A ring trial organized by the Association of Applied Hygiene (VAH) on the bactericidal efficacy of an ethanol-based hand rub was carried out in 17 laboratories according to EN 1500 with the aim of describing the variability of test results and fulfilment of the methodological acceptance criteria. As a test product, a hand rub based on 80% ethanol (w/w) was tested in comparison with the reference alcohol (60% iso-propanol, v/v) in a crossover design. After pre-washing and contamination following the norm, hands were treated either with the reference alcohol (2 × 3 mL for 2 × 30 s) or the test product (3 mL in 30 s). Post-decontamination values were determined immediately after the rub-in period. Validated neutralizers were used. The arithmetic means of all individual log pre-values, post-values and reduction values were calculated per laboratory. Non-inferiority was assumed when the Hodges–Lehmann 97.5% confidence limit was <0.6 in comparison with the reference. A z-score was calculated to determine the laboratory performance. Two laboratories did not meet the acceptance criteria and were excluded from the analysis. The bactericidal efficacy of the test product was non-inferior to the reference product in four laboratories and not non-inferior in 11 laboratories. The z-score for the Hodges–Lehmann 97.5% confidence limit indicated a satisfactory performance in all laboratories. We consider the EN 1500 test method to be robust in terms of the variability of test results. For products of borderline efficacy, the evaluation should be based on more than one test.

中文翻译：

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17 个实验室根据 EN 1500 对基于 80%（w/w）的洗手液进行的测试结果的可靠性如何？

应用卫生协会 (VAH) 根据 EN 1500 在 17 个实验室中组织了一项关于乙醇洗手液杀菌功效的环形试验，目的是描述测试结果的可变性并满足方法学认可标准。作为测试产品，在交叉设计中对基于 80% 乙醇（w/w）的洗手液与参考酒精（60% 异丙醇，v/v）进行了比较。按照标准进行预清洗和污染后，用参考酒精（2 × 3 mL，2 × 30 s）或测试产品（3 mL，30 s）处理手。擦洗期后立即测定去污后值。使用经过验证的中和剂。每个实验室计算所有单独日志前值、后值和减少值的算术平均值。当与参考相比，Hodges-Lehmann 97.5% 置信限 <0.6 时，假定非劣效性。计算 z 分数以确定实验室表现。两个实验室不符合验收标准，被排除在分析之外。受试产品的杀菌功效在 4 个实验室中不劣于参比产品，在 11 个实验室中也不劣于参比产品。 Hodges-Lehmann 97.5% 置信限的 z 分数表明所有实验室的性能均令人满意。我们认为 EN 1500 测试方法在测试结果的可变性方面是稳健的。对于具有临界功效的产品，评估应基于不止一项测试。