title: Disease risk score as a confounder summary method: systematic review and recommendations.
abstract: OBJECTIVE
  To systematically examine trends and applications of the disease risk score (DRS) as a confounder summary method.
  
  
  METHODS
  We completed a systematic search of MEDLINE and Web of Science® to identify all English language articles that applied DRS methods. We tabulated the number of publications by year and type (empirical application, methodological contribution, or review paper) and summarized methods used in empirical applications overall and by publication year (<2000, ≥2000).
  
  
  RESULTS
  Of 714 unique articles identified, 97 examined DRS methods and 86 were empirical applications. We observed a bimodal distribution in the number of publications over time, with a peak 1979-1980, and resurgence since 2000. The majority of applications with methodological detail derived DRS using logistic regression (47%), used DRS as a categorical variable in regression (93%), and applied DRS in a non-experimental cohort (47%) or case-control (42%) study. Few studies examined effect modification by outcome risk (23%).
  
  
  CONCLUSIONS
  Use of DRS methods has increased yet remains low. Comparative effectiveness research may benefit from more DRS applications, particularly to examine effect modification by outcome risk. Standardized terminology may facilitate identification, application, and comprehension of DRS methods. More research is needed to support the application of DRS methods, particularly in case-control studies.
authors.affiliation: Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.
authors.forename: Mina
authors.initials: M
authors.lastname: Tadrous
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Gagne
authors.forename: Til
authors.initials: T
authors.lastname: Stürmer
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Cadarette
mesh_terms: D000818:Animals; D015986:Confounding Factors, Epidemiologic; D004194:Disease / Q000209:etiology; D006287:Health Planning Guidelines; D006801:Humans; D012107:Research Design / Q000592:standards*; D012307:Risk Factors