Drug safety data mining with a tree-based scan statistic

UMMS Affiliation

Meyers Primary Care Institute

Publication Date


Document Type



Drug Toxicity; Safety; Data Mining; Product Surveillance, Postmarketing


Computer Sciences | Epidemiology | Health and Medical Administration | Health Services Research | Medical Biotechnology | Medical Toxicology | Pharmacy and Pharmaceutical Sciences | Statistics and Probability


PURPOSE: In post-marketing drug safety surveillance, data mining can potentially detect rare but serious adverse events. Assessing an entire collection of drug-event pairs is traditionally performed on a predefined level of granularity. It is unknown a priori whether a drug causes a very specific or a set of related adverse events, such as mitral valve disorders, all valve disorders, or different types of heart disease. This methodological paper evaluates the tree-based scan statistic data mining method to enhance drug safety surveillance.

METHODS: We use a three-million-member electronic health records database from the HMO Research Network. Using the tree-based scan statistic, we assess the safety of selected antifungal and diabetes drugs, simultaneously evaluating overlapping diagnosis groups at different granularity levels, adjusting for multiple testing. Expected and observed adverse event counts were adjusted for age, sex, and health plan, producing a log likelihood ratio test statistic.

RESULTS: Out of 732 evaluated disease groupings, 24 were statistically significant, divided among 10 non-overlapping disease categories. Five of the 10 signals are known adverse effects, four are likely due to confounding by indication, while one may warrant further investigation.

CONCLUSION: The tree-based scan statistic can be successfully applied as a data mining tool in drug safety surveillance using observational data. The total number of statistical signals was modest and does not imply a causal relationship. Rather, data mining results should be used to generate candidate drug-event pairs for rigorous epidemiological studies to evaluate the individual and comparative safety profiles of drugs.

Copyright (c) 2013 John Wiley and Sons, Ltd.

DOI of Published Version



Pharmacoepidemiol Drug Saf. 2013 May;22(5):517-23. doi: 10.1002/pds.3423. Link to article on publisher's site

Journal/Book/Conference Title

Pharmacoepidemiology and drug safety

Related Resources

Link to Article in PubMed

PubMed ID