A Method for the Minimization of Competition Bias in Signal Detection from Spontaneous Reporting Databases



The two methods for minimizing competition bias in signal of disproportionate reporting (SDR) detection—masking factor (MF) and masking ratio (MR)—have focused on the strength of disproportionality for identifying competitors and have been tested using competitors at the drug level.


The aim of this study was to develop a method that relies on identifying competitors by considering the proportion of reports of adverse events (AEs) that mention the drug class at an adequate level of drug grouping to increase sensitivity (Se) for SDR unmasking, and its comparison with MF and MR.


Reports in the French spontaneous reporting database between 2000 and 2005 were selected. Five AEs were considered: myocardial infarction, pancreatitis, aplastic anemia, convulsions, and gastrointestinal bleeding; related reports were retrieved using standardized Medical Dictionary for Regulatory Activities (MedDRA®) queries. Potential competitors of AEs were identified using the developed method, i.e. Competition Index (ComIn), as well as MF and MR. All three methods were tested according to Anatomical Therapeutic Chemical (ATC) classification levels 2–5. For each AE, SDR detection was performed, first in the complete database, and second after removing reports mentioning competitors; SDRs only detected after the removal were unmasked. All unmasked SDRs were validated using the Summary of Product Characteristics, and constituted the reference dataset used for computing the performance for SDR unmasking (area under the curve [AUC], Se).


Performance of the ComIn was highest when considering competitors at ATC level 3 (AUC: 62 %; Se: 52 %); similar results were obtained with MF and MR.


The ComIn could greatly minimize the competition bias in SDR detection. Further study using a larger dataset is needed.

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The authors would like to thank all members of the 31 French regional pharmacovigilance centers, as well as the French National Agency for Drug Safety [Agence Nationale de Sécurité des Médicaments et des produits de santé (ANSM)] for providing the data.

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Correspondence to Mickael Arnaud.

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This study is part of a research project that has received funding from the French National Agency for Drug Safety (ANSM) under Grant agreement number 2013–2050—the SPOON-KIM project. The funding source had no role in study design; collection, analysis, and interpretation of data; writing of the report; and the decision to submit the paper for publication.

Conflict of interest

Mickael Arnaud, Francesco Salvo, Ismaïl Ahmed, Philip Robinson, Nicholas Moore, Bernard Bégaud, Pascale Tubert-Bitter, and Antoine Pariente have no conflicts of interest that are directly relevant to the content of this study.

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Arnaud, M., Salvo, F., Ahmed, I. et al. A Method for the Minimization of Competition Bias in Signal Detection from Spontaneous Reporting Databases. Drug Saf 39, 251–260 (2016). https://doi.org/10.1007/s40264-015-0375-8

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