title: A secure distributed logistic regression protocol for the detection of rare adverse drug events.
abstract: BACKGROUND
  There is limited capacity to assess the comparative risks of medications after they enter the market. For rare adverse events, the pooling of data from multiple sources is necessary to have the power and sufficient population heterogeneity to detect differences in safety and effectiveness in genetic, ethnic and clinically defined subpopulations. However, combining datasets from different data custodians or jurisdictions to perform an analysis on the pooled data creates significant privacy concerns that would need to be addressed. Existing protocols for addressing these concerns can result in reduced analysis accuracy and can allow sensitive information to leak.
  
  
  OBJECTIVE
  To develop a secure distributed multi-party computation protocol for logistic regression that provides strong privacy guarantees.
  
  
  METHODS
  We developed a secure distributed logistic regression protocol using a single analysis center with multiple sites providing data. A theoretical security analysis demonstrates that the protocol is robust to plausible collusion attacks and does not allow the parties to gain new information from the data that are exchanged among them. The computational performance and accuracy of the protocol were evaluated on simulated datasets.
  
  
  RESULTS
  The computational performance scales linearly as the dataset sizes increase. The addition of sites results in an exponential growth in computation time. However, for up to five sites, the time is still short and would not affect practical applications. The model parameters are the same as the results on pooled raw data analyzed in SAS, demonstrating high model accuracy.
  
  
  CONCLUSIONS
  The proposed protocol and prototype system would allow the development of logistic regression models in a secure manner without requiring the sharing of personal health information. This can alleviate one of the key barriers to the establishment of large-scale post-marketing surveillance programs. We extended the secure protocol to account for correlations among patients within sites through generalized estimating equations, and to accommodate other link functions by extending it to generalized linear models.
authors.affiliation: CHEO Research Institute, Ottawa, Ontario, Canada. kelemam@ehealthinformation.ca
authors.forename: Khaled
authors.initials: K
authors.lastname: El Emam
authors.forename: Saeed
authors.initials: S
authors.lastname: Samet
authors.forename: Luk
authors.initials: L
authors.lastname: Arbuckle
authors.forename: Robyn
authors.initials: R
authors.lastname: Tamblyn
authors.forename: Craig
authors.initials: C
authors.lastname: Earle
authors.forename: Murat
authors.initials: M
authors.lastname: Kantarcioglu
mesh_terms: D056808:Biostatistics; D003195:Computer Communication Networks; D064420:Drug-Related Side Effects and Adverse Reactions / Q000175:diagnosis*; D006801:Humans; D016015:Logistic Models; D011358:Product Surveillance, Postmarketing / Q000379:methods*