title: Drug Adverse Event Detection in Health Plan Data Using the Gamma Poisson Shrinker and Comparison to the Tree-based Scan Statistic.
abstract: BACKGROUND
  Drug adverse event (AE) signal detection using the Gamma Poisson Shrinker (GPS) is commonly applied in spontaneous reporting. AE signal detection using large observational health plan databases can expand medication safety surveillance.
  
  
  METHODS
  Using data from nine health plans, we conducted a pilot study to evaluate the implementation and findings of the GPS approach for two antifungal drugs, terbinafine and itraconazole, and two diabetes drugs, pioglitazone and rosiglitazone. We evaluated 1676 diagnosis codes grouped into 183 different clinical concepts and four levels of granularity. Several signaling thresholds were assessed. GPS results were compared to findings from a companion study using the identical analytic dataset but an alternative statistical method-the tree-based scan statistic (TreeScan).
  
  
  RESULTS
  We identified 71 statistical signals across two signaling thresholds and two methods, including closely-related signals of overlapping diagnosis definitions. Initial review found that most signals represented known adverse drug reactions or confounding. About 31% of signals met the highest signaling threshold.
  
  
  CONCLUSIONS
  The GPS method was successfully applied to observational health plan data in a distributed data environment as a drug safety data mining method. There was substantial concordance between the GPS and TreeScan approaches. Key method implementation decisions relate to defining exposures and outcomes and informed choice of signaling thresholds.
authors.affiliation: Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, 133 Brookline Avenue, 6th Floor, Boston, MA 02215, USA. jeff_brown@hphc.org.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Brown
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Petronis
authors.forename: Andrew
authors.initials: A
authors.lastname: Bate
authors.forename: Fang
authors.initials: F
authors.lastname: Zhang
authors.forename: Inna
authors.initials: I
authors.lastname: Dashevsky
authors.forename: Martin
authors.initials: M
authors.lastname: Kulldorff
authors.forename: Taliser R
authors.initials: TR
authors.lastname: Avery
authors.forename: Robert L
authors.initials: RL
authors.lastname: Davis
authors.forename: K Arnold
authors.initials: KA
authors.lastname: Chan
authors.forename: Susan E
authors.initials: SE
authors.lastname: Andrade
authors.forename: Denise
authors.initials: D
authors.lastname: Boudreau
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Gunter
authors.forename: Lisa
authors.initials: L
authors.lastname: Herrinton
authors.forename: Pamala A
authors.initials: PA
authors.lastname: Pawloski
authors.forename: Marsha A
authors.initials: MA
authors.lastname: Raebel
authors.forename: Douglas
authors.initials: D
authors.lastname: Roblin
authors.forename: David
authors.initials: D
authors.lastname: Smith
authors.forename: Robert
authors.initials: R
authors.lastname: Reynolds