title: Additive and multiplicative hazards modeling for recurrent event data analysis.
abstract: BACKGROUND
  Sequentially ordered multivariate failure time or recurrent event duration data are commonly observed in biomedical longitudinal studies. In general, standard hazard regression methods cannot be applied because of correlation between recurrent failure times within a subject and induced dependent censoring. Multiplicative and additive hazards models provide the two principal frameworks for studying the association between risk factors and recurrent event durations for the analysis of multivariate failure time data.
  
  
  METHODS
  Using emergency department visits data, we illustrated and compared the additive and multiplicative hazards models for analysis of recurrent event durations under (i) a varying baseline with a common coefficient effect and (ii) a varying baseline with an order-specific coefficient effect.
  
  
  RESULTS
  The analysis showed that both additive and multiplicative hazards models, with varying baseline and common coefficient effects, gave similar results with regard to covariates selected to remain in the model of our real dataset. The confidence intervals of the multiplicative hazards model were wider than the additive hazards model for each of the recurrent events. In addition, in both models, the confidence interval gets wider as the revisit order increased because the risk set decreased as the order of visit increased.
  
  
  CONCLUSIONS
  Due to the frequency of multiple failure times or recurrent event duration data in clinical and epidemiologic studies, the multiplicative and additive hazards models are widely applicable and present different information. Hence, it seems desirable to use them, not as alternatives to each other, but together as complementary methods, to provide a more comprehensive understanding of data.
authors.affiliation: Department of Community Health & Epidemiology College of Medicine, University of Saskatchewan, Saskatoon, Canada. hyun.lim@usask.ca
authors.forename: Hyun J
authors.initials: HJ
authors.lastname: Lim
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000465:Algorithms; D003627:Data Interpretation, Statistical; D004638:Emergency Treatment / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D016016:Proportional Hazards Models; D016019:Survival Analysis; D014193:Trauma Centers / Q000706:statistics & numerical data; D014948:Wounds, Gunshot / Q000628:therapy