Abstract Background Current ICH guidelines, e.g. ICH E6 (R3), advocate a risk-based statistical review of clinical trial data to identify anomalies. The open-source R package, clinical trial anomaly spotter (CTAS) has been developed by Bayer and the Intercompany Quality Analytics (IMPALA) consortium, helps detect inconsistencies in subject time series data at both site and subject levels, facilitating timely intervention. Methods CTAS analyzes time series of equal length. Each subject-level time series is summarized as six optional scalars: mean, standard deviation, range, relative unique value count, autocorrelation and local outlier factor. To detect site-level anomalies, sites can be scored using 3 different scoring methods. The performance of the CTAS algorithm was tested using simulations, artificially introducing site anomalies of various types and degrees into clinical trial data sets. Results We found that CTAS can reliably detect site anomalies depending on the degree of the anomaly introduced. Less complex anomalies such as mean were easier to detect than complex outlier such as local outlier factor. The three scoring methods differed in their ability to detect anomalous sites with a small number of patients and their false positive rates. Conclusions CTAS is a valuable tool for timely detection of outliers in clinical data, suitable for integration into risk-based strategies. Choosing the appropriate site anomaly scoring method is crucial for handling sites with fewer subjects effectively.
Tiikkainen et al. (2026) studied this question.